#include "tracercore.h"
#include "usterr.h"
+struct ltt_reserve_switch_offsets {
+ long begin, end, old;
+ long begin_switch, end_switch_current, end_switch_old;
+ size_t before_hdr_pad, size;
+};
+
+
static DEFINE_MUTEX(ust_buffers_channels_mutex);
static LIST_HEAD(ust_buffers_channels);
return result;
}
-static int ust_buffers_init_buffer(struct ltt_trace_struct *trace,
+/* _ust_buffers_write()
+ *
+ * @buf: destination buffer
+ * @offset: offset in destination
+ * @src: source buffer
+ * @len: length of source
+ * @cpy: already copied
+ */
+
+void _ust_buffers_write(struct ust_buffer *buf, size_t offset,
+ const void *src, size_t len, ssize_t cpy)
+{
+ do {
+ len -= cpy;
+ src += cpy;
+ offset += cpy;
+
+ WARN_ON(offset >= buf->buf_size);
+
+ cpy = min_t(size_t, len, buf->buf_size - offset);
+ ust_buffers_do_copy(buf->buf_data + offset, src, cpy);
+ } while (unlikely(len != cpy));
+}
+
+static int ust_buffers_init_buffer(struct ust_trace *trace,
struct ust_channel *ltt_chan,
struct ust_buffer *buf,
unsigned int n_subbufs);
if(subbuf_size == 0 || subbuf_cnt == 0)
return -1;
+ /* Check that the subbuffer size is larger than a page. */
+ WARN_ON_ONCE(subbuf_size < PAGE_SIZE);
+
+ /*
+ * Make sure the number of subbuffers and subbuffer size are power of 2.
+ */
+ WARN_ON_ONCE(hweight32(subbuf_size) != 1);
+ WARN_ON(hweight32(subbuf_cnt) != 1);
+
chan->version = UST_CHANNEL_VERSION;
chan->subbuf_cnt = subbuf_cnt;
chan->subbuf_size = subbuf_size;
chan->subbuf_size_order = get_count_order(subbuf_size);
- chan->alloc_size = FIX_SIZE(subbuf_size * subbuf_cnt);
+ chan->alloc_size = subbuf_size * subbuf_cnt;
kref_init(&chan->kref);
mutex_unlock(&ust_buffers_channels_mutex);
}
-/* _ust_buffers_write()
- *
- * @buf: destination buffer
- * @offset: offset in destination
- * @src: source buffer
- * @len: length of source
- * @cpy: already copied
- */
-
-void _ust_buffers_write(struct ust_buffer *buf, size_t offset,
- const void *src, size_t len, ssize_t cpy)
-{
- do {
- len -= cpy;
- src += cpy;
- offset += cpy;
-
- WARN_ON(offset >= buf->buf_size);
-
- cpy = min_t(size_t, len, buf->buf_size - offset);
- ust_buffers_do_copy(buf->buf_data + offset, src, cpy);
- } while (unlikely(len != cpy));
-}
-
-void *ltt_buffers_offset_address(struct ust_buffer *buf, size_t offset)
-{
- return ((char *)buf->buf_data)+offset;
-}
-
/*
* -------
*/
-/*
- * Last TSC comparison functions. Check if the current TSC overflows
- * LTT_TSC_BITS bits from the last TSC read. Reads and writes last_tsc
- * atomically.
- */
-
-/* FIXME: does this test work properly? */
-#if (BITS_PER_LONG == 32)
-static inline void save_last_tsc(struct ust_buffer *ltt_buf,
- u64 tsc)
-{
- ltt_buf->last_tsc = (unsigned long)(tsc >> LTT_TSC_BITS);
-}
-
-static inline int last_tsc_overflow(struct ust_buffer *ltt_buf,
- u64 tsc)
-{
- unsigned long tsc_shifted = (unsigned long)(tsc >> LTT_TSC_BITS);
-
- if (unlikely((tsc_shifted - ltt_buf->last_tsc)))
- return 1;
- else
- return 0;
-}
-#else
-static inline void save_last_tsc(struct ust_buffer *ltt_buf,
- u64 tsc)
-{
- ltt_buf->last_tsc = (unsigned long)tsc;
-}
-
-static inline int last_tsc_overflow(struct ust_buffer *ltt_buf,
- u64 tsc)
-{
- if (unlikely((tsc - ltt_buf->last_tsc) >> LTT_TSC_BITS))
- return 1;
- else
- return 0;
-}
-#endif
-
-/*
- * A switch is done during tracing or as a final flush after tracing (so it
- * won't write in the new sub-buffer).
- */
-enum force_switch_mode { FORCE_ACTIVE, FORCE_FLUSH };
-
static void ust_buffers_destroy_buffer(struct ust_channel *ltt_chan, int cpu);
static void ltt_force_switch(struct ust_buffer *buf,
/*
* Trace callbacks
*/
-static void ltt_buffer_begin_callback(struct ust_buffer *buf,
+static void ltt_buffer_begin(struct ust_buffer *buf,
u64 tsc, unsigned int subbuf_idx)
{
struct ust_channel *channel = buf->chan;
struct ltt_subbuffer_header *header =
(struct ltt_subbuffer_header *)
- ltt_buffers_offset_address(buf,
+ ust_buffers_offset_address(buf,
subbuf_idx * buf->chan->subbuf_size);
header->cycle_count_begin = tsc;
* offset is assumed to never be 0 here : never deliver a completely empty
* subbuffer. The lost size is between 0 and subbuf_size-1.
*/
-static notrace void ltt_buffer_end_callback(struct ust_buffer *buf,
+static notrace void ltt_buffer_end(struct ust_buffer *buf,
u64 tsc, unsigned int offset, unsigned int subbuf_idx)
{
struct ltt_subbuffer_header *header =
(struct ltt_subbuffer_header *)
- ltt_buffers_offset_address(buf,
+ ust_buffers_offset_address(buf,
subbuf_idx * buf->chan->subbuf_size);
header->lost_size = SUBBUF_OFFSET((buf->chan->subbuf_size - offset),
header->cycle_count_end = tsc;
header->events_lost = local_read(&buf->events_lost);
header->subbuf_corrupt = local_read(&buf->corrupted_subbuffers);
-
-}
-
-void (*wake_consumer)(void *, int) = NULL;
-
-void relay_set_wake_consumer(void (*wake)(void *, int))
-{
- wake_consumer = wake;
-}
-
-void relay_wake_consumer(void *arg, int finished)
-{
- if(wake_consumer)
- wake_consumer(arg, finished);
-}
-
-static notrace void ltt_deliver(struct ust_buffer *buf, unsigned int subbuf_idx,
- long commit_count)
-{
- int result;
-
-//ust// #ifdef CONFIG_LTT_VMCORE
- local_set(&buf->commit_seq[subbuf_idx], commit_count);
-//ust// #endif
-
- /* wakeup consumer */
- result = write(buf->data_ready_fd_write, "1", 1);
- if(result == -1) {
- PERROR("write (in ltt_relay_buffer_flush)");
- ERR("this should never happen!");
- }
-//ust// atomic_set(<t_buf->wakeup_readers, 1);
}
/*
unsigned int subbuf_idx,
long offset)
{
-//ust// struct ltt_channel_struct *ltt_channel =
-//ust// (struct ltt_channel_struct *)buf->chan->private_data;
-//ust// struct ltt_channel_buf_struct *ltt_buf = ltt_channel->buf;
-//ust//
-//ust// ltt_relay_wake_writers(ltt_buf);
}
-int ust_buffers_do_get_subbuf(struct ust_buffer *buf, long *pconsumed_old)
+/*
+ * Promote compiler barrier to a smp_mb().
+ * For the specific LTTng case, this IPI call should be removed if the
+ * architecture does not reorder writes. This should eventually be provided by
+ * a separate architecture-specific infrastructure.
+ */
+static void remote_mb(void *info)
+{
+ smp_mb();
+}
+
+int ust_buffers_get_subbuf(struct ust_buffer *buf, long *consumed)
{
struct ust_channel *channel = buf->chan;
long consumed_old, consumed_idx, commit_count, write_offset;
+//ust// int retval;
+
consumed_old = atomic_long_read(&buf->consumed);
consumed_idx = SUBBUF_INDEX(consumed_old, buf->chan);
- commit_count = local_read(&buf->commit_count[consumed_idx]);
+ commit_count = local_read(&buf->commit_count[consumed_idx].cc_sb);
/*
* Make sure we read the commit count before reading the buffer
* data and the write offset. Correct consumed offset ordering
* wrt commit count is insured by the use of cmpxchg to update
* the consumed offset.
+ * smp_call_function_single can fail if the remote CPU is offline,
+ * this is OK because then there is no wmb to execute there.
+ * If our thread is executing on the same CPU as the on the buffers
+ * belongs to, we don't have to synchronize it at all. If we are
+ * migrated, the scheduler will take care of the memory barriers.
+ * Normally, smp_call_function_single() should ensure program order when
+ * executing the remote function, which implies that it surrounds the
+ * function execution with :
+ * smp_mb()
+ * send IPI
+ * csd_lock_wait
+ * recv IPI
+ * smp_mb()
+ * exec. function
+ * smp_mb()
+ * csd unlock
+ * smp_mb()
+ *
+ * However, smp_call_function_single() does not seem to clearly execute
+ * such barriers. It depends on spinlock semantic to provide the barrier
+ * before executing the IPI and, when busy-looping, csd_lock_wait only
+ * executes smp_mb() when it has to wait for the other CPU.
+ *
+ * I don't trust this code. Therefore, let's add the smp_mb() sequence
+ * required ourself, even if duplicated. It has no performance impact
+ * anyway.
+ *
+ * smp_mb() is needed because smp_rmb() and smp_wmb() only order read vs
+ * read and write vs write. They do not ensure core synchronization. We
+ * really have to ensure total order between the 3 barriers running on
+ * the 2 CPUs.
+ */
+//ust// #ifdef LTT_NO_IPI_BARRIER
+ /*
+ * Local rmb to match the remote wmb to read the commit count before the
+ * buffer data and the write offset.
*/
smp_rmb();
+//ust// #else
+//ust// if (raw_smp_processor_id() != buf->cpu) {
+//ust// smp_mb(); /* Total order with IPI handler smp_mb() */
+//ust// smp_call_function_single(buf->cpu, remote_mb, NULL, 1);
+//ust// smp_mb(); /* Total order with IPI handler smp_mb() */
+//ust// }
+//ust// #endif
+
write_offset = local_read(&buf->offset);
/*
* Check that the subbuffer we are trying to consume has been
return -EAGAIN;
}
- *pconsumed_old = consumed_old;
+ /* FIXME: is this ok to disable the reading feature? */
+//ust// retval = update_read_sb_index(buf, consumed_idx);
+//ust// if (retval)
+//ust// return retval;
+
+ *consumed = consumed_old;
+
return 0;
}
-int ust_buffers_do_put_subbuf(struct ust_buffer *buf, u32 uconsumed_old)
+int ust_buffers_put_subbuf(struct ust_buffer *buf, unsigned long uconsumed_old)
{
long consumed_new, consumed_old;
return 0;
}
+//ust// static void switch_buffer(unsigned long data)
+//ust// {
+//ust// struct ltt_channel_buf_struct *ltt_buf =
+//ust// (struct ltt_channel_buf_struct *)data;
+//ust// struct rchan_buf *buf = ltt_buf->rbuf;
+//ust//
+//ust// if (buf)
+//ust// ltt_force_switch(buf, FORCE_ACTIVE);
+//ust//
+//ust// ltt_buf->switch_timer.expires += ltt_buf->switch_timer_interval;
+//ust// add_timer_on(<t_buf->switch_timer, smp_processor_id());
+//ust// }
+//ust//
+//ust// static void start_switch_timer(struct ltt_channel_struct *ltt_channel)
+//ust// {
+//ust// struct rchan *rchan = ltt_channel->trans_channel_data;
+//ust// int cpu;
+//ust//
+//ust// if (!ltt_channel->switch_timer_interval)
+//ust// return;
+//ust//
+//ust// // TODO : hotplug
+//ust// for_each_online_cpu(cpu) {
+//ust// struct ltt_channel_buf_struct *ltt_buf;
+//ust// struct rchan_buf *buf;
+//ust//
+//ust// buf = rchan->buf[cpu];
+//ust// ltt_buf = buf->chan_private;
+//ust// buf->random_access = 1;
+//ust// ltt_buf->switch_timer_interval =
+//ust// ltt_channel->switch_timer_interval;
+//ust// init_timer(<t_buf->switch_timer);
+//ust// ltt_buf->switch_timer.function = switch_buffer;
+//ust// ltt_buf->switch_timer.expires = jiffies +
+//ust// ltt_buf->switch_timer_interval;
+//ust// ltt_buf->switch_timer.data = (unsigned long)ltt_buf;
+//ust// add_timer_on(<t_buf->switch_timer, cpu);
+//ust// }
+//ust// }
+//ust//
+//ust// /*
+//ust// * Cannot use del_timer_sync with add_timer_on, so use an IPI to locally
+//ust// * delete the timer.
+//ust// */
+//ust// static void stop_switch_timer_ipi(void *info)
+//ust// {
+//ust// struct ltt_channel_buf_struct *ltt_buf =
+//ust// (struct ltt_channel_buf_struct *)info;
+//ust//
+//ust// del_timer(<t_buf->switch_timer);
+//ust// }
+//ust//
+//ust// static void stop_switch_timer(struct ltt_channel_struct *ltt_channel)
+//ust// {
+//ust// struct rchan *rchan = ltt_channel->trans_channel_data;
+//ust// int cpu;
+//ust//
+//ust// if (!ltt_channel->switch_timer_interval)
+//ust// return;
+//ust//
+//ust// // TODO : hotplug
+//ust// for_each_online_cpu(cpu) {
+//ust// struct ltt_channel_buf_struct *ltt_buf;
+//ust// struct rchan_buf *buf;
+//ust//
+//ust// buf = rchan->buf[cpu];
+//ust// ltt_buf = buf->chan_private;
+//ust// smp_call_function(stop_switch_timer_ipi, ltt_buf, 1);
+//ust// buf->random_access = 0;
+//ust// }
+//ust// }
+
+static void ust_buffers_print_written(struct ust_channel *chan,
+ long cons_off, unsigned int cpu)
+{
+ struct ust_buffer *buf = chan->buf[cpu];
+ long cons_idx, events_count;
+
+ cons_idx = SUBBUF_INDEX(cons_off, chan);
+ events_count = local_read(&buf->commit_count[cons_idx].events);
+
+ if (events_count)
+ printk(KERN_INFO
+ "channel %s: %lu events written (cpu %u, index %lu)\n",
+ chan->channel_name, events_count, cpu, cons_idx);
+}
+
static void ltt_relay_print_subbuffer_errors(
struct ust_channel *channel,
long cons_off, int cpu)
{
struct ust_buffer *ltt_buf = channel->buf[cpu];
- long cons_idx, commit_count, write_offset;
+ long cons_idx, commit_count, commit_count_sb, write_offset;
cons_idx = SUBBUF_INDEX(cons_off, channel);
- commit_count = local_read(<t_buf->commit_count[cons_idx]);
+ commit_count = local_read(<t_buf->commit_count[cons_idx].cc);
+ commit_count_sb = local_read(<t_buf->commit_count[cons_idx].cc_sb);
+
/*
* No need to order commit_count and write_offset reads because we
* execute after trace is stopped when there are no readers left.
*/
write_offset = local_read(<t_buf->offset);
WARN( "LTT : unread channel %s offset is %ld "
- "and cons_off : %ld\n",
- channel->channel_name, write_offset, cons_off);
+ "and cons_off : %ld (cpu %d)\n",
+ channel->channel_name, write_offset, cons_off, cpu);
/* Check each sub-buffer for non filled commit count */
if (((commit_count - channel->subbuf_size) & channel->commit_count_mask)
- (BUFFER_TRUNC(cons_off, channel) >> channel->n_subbufs_order) != 0) {
ERR("LTT : %s : subbuffer %lu has non filled "
- "commit count %lu.\n",
- channel->channel_name, cons_idx, commit_count);
+ "commit count [cc, cc_sb] [%lu,%lu].\n",
+ channel->channel_name, cons_idx, commit_count, commit_count_sb);
}
ERR("LTT : %s : commit count : %lu, subbuf size %zd\n",
channel->channel_name, commit_count,
channel->subbuf_size);
}
-static void ltt_relay_print_errors(struct ltt_trace_struct *trace,
+static void ltt_relay_print_errors(struct ust_trace *trace,
struct ust_channel *channel, int cpu)
{
struct ust_buffer *ltt_buf = channel->buf[cpu];
if (!channel)
return;
+ for (cons_off = 0; cons_off < rchan->alloc_size;
+ cons_off = SUBBUF_ALIGN(cons_off, rchan))
+ ust_buffers_print_written(ltt_chan, cons_off, cpu);
for (cons_off = atomic_long_read(<t_buf->consumed);
(SUBBUF_TRUNC(local_read(<t_buf->offset),
channel)
static void ltt_relay_print_buffer_errors(struct ust_channel *channel, int cpu)
{
- struct ltt_trace_struct *trace = channel->trace;
+ struct ust_trace *trace = channel->trace;
struct ust_buffer *ltt_buf = channel->buf[cpu];
if (local_read(<t_buf->events_lost))
- ERR("channel %s: %ld events lost",
+ ERR("channel %s: %ld events lost (cpu %d)",
channel->channel_name,
- local_read(<t_buf->events_lost));
+ local_read(<t_buf->events_lost), cpu);
if (local_read(<t_buf->corrupted_subbuffers))
- ERR("channel %s : %ld corrupted subbuffers",
+ ERR("channel %s : %ld corrupted subbuffers (cpu %d)",
channel->channel_name,
- local_read(<t_buf->corrupted_subbuffers));
+ local_read(<t_buf->corrupted_subbuffers), cpu);
ltt_relay_print_errors(trace, channel, cpu);
}
/*
* Create ltt buffer.
*/
-//ust// static int ltt_relay_create_buffer(struct ltt_trace_struct *trace,
+//ust// static int ltt_relay_create_buffer(struct ust_trace *trace,
//ust// struct ltt_channel_struct *ltt_chan, struct rchan_buf *buf,
//ust// unsigned int cpu, unsigned int n_subbufs)
//ust// {
//ust// struct ltt_channel_buf_struct *ltt_buf =
//ust// percpu_ptr(ltt_chan->buf, cpu);
//ust// unsigned int j;
-//ust//
+//ust//
//ust// ltt_buf->commit_count =
//ust// kzalloc_node(sizeof(ltt_buf->commit_count) * n_subbufs,
//ust// GFP_KERNEL, cpu_to_node(cpu));
//ust// init_waitqueue_head(<t_buf->write_wait);
//ust// atomic_set(<t_buf->wakeup_readers, 0);
//ust// spin_lock_init(<t_buf->full_lock);
-//ust//
+//ust//
//ust// ltt_buffer_begin_callback(buf, trace->start_tsc, 0);
//ust// /* atomic_add made on local variable on data that belongs to
//ust// * various CPUs : ok because tracing not started (for this cpu). */
//ust// local_add(ltt_subbuffer_header_size(), <t_buf->commit_count[0]);
-//ust//
+//ust//
//ust// local_set(<t_buf->events_lost, 0);
//ust// local_set(<t_buf->corrupted_subbuffers, 0);
-//ust//
+//ust//
//ust// return 0;
//ust// }
-static int ust_buffers_init_buffer(struct ltt_trace_struct *trace,
+static int ust_buffers_init_buffer(struct ust_trace *trace,
struct ust_channel *ltt_chan, struct ust_buffer *buf,
unsigned int n_subbufs)
{
int result;
buf->commit_count =
- zmalloc(sizeof(buf->commit_count) * n_subbufs);
+ zmalloc(sizeof(*buf->commit_count) * n_subbufs);
if (!buf->commit_count)
return -ENOMEM;
kref_get(&trace->kref);
local_set(&buf->offset, ltt_subbuffer_header_size());
atomic_long_set(&buf->consumed, 0);
atomic_long_set(&buf->active_readers, 0);
- for (j = 0; j < n_subbufs; j++)
- local_set(&buf->commit_count[j], 0);
+ for (j = 0; j < n_subbufs; j++) {
+ local_set(&buf->commit_count[j].cc, 0);
+ local_set(&buf->commit_count[j].cc_sb, 0);
+ }
//ust// init_waitqueue_head(&buf->write_wait);
//ust// atomic_set(&buf->wakeup_readers, 0);
//ust// spin_lock_init(&buf->full_lock);
- ltt_buffer_begin_callback(buf, trace->start_tsc, 0);
+ ltt_buffer_begin(buf, trace->start_tsc, 0);
- local_add(ltt_subbuffer_header_size(), &buf->commit_count[0]);
+ local_add(ltt_subbuffer_header_size(), &buf->commit_count[0].cc);
local_set(&buf->events_lost, 0);
local_set(&buf->corrupted_subbuffers, 0);
/* FIXME: use this function */
static void ust_buffers_destroy_buffer(struct ust_channel *ltt_chan, int cpu)
{
- struct ltt_trace_struct *trace = ltt_chan->trace;
+ struct ust_trace *trace = ltt_chan->trace;
struct ust_buffer *ltt_buf = ltt_chan->buf[cpu];
kref_put(<t_chan->trace->ltt_transport_kref,
/*
* Create channel.
*/
-static int ust_buffers_create_channel(const char *trace_name, struct ltt_trace_struct *trace,
+static int ust_buffers_create_channel(const char *trace_name, struct ust_trace *trace,
const char *channel_name, struct ust_channel *ltt_chan,
unsigned int subbuf_size, unsigned int n_subbufs, int overwrite)
{
kref_init(<t_chan->kref);
ltt_chan->trace = trace;
- ltt_chan->buffer_begin = ltt_buffer_begin_callback;
- ltt_chan->buffer_end = ltt_buffer_end_callback;
ltt_chan->overwrite = overwrite;
ltt_chan->n_subbufs_order = get_count_order(n_subbufs);
ltt_chan->commit_count_mask = (~0UL >> ltt_chan->n_subbufs_order);
kref_put(&channel->kref, ltt_relay_release_channel);
}
-struct ltt_reserve_switch_offsets {
- long begin, end, old;
- long begin_switch, end_switch_current, end_switch_old;
- long commit_count, reserve_commit_diff;
- size_t before_hdr_pad, size;
-};
+//ust// /*
+//ust// * Returns :
+//ust// * 0 if ok
+//ust// * !0 if execution must be aborted.
+//ust// */
+//ust// static inline int ltt_relay_try_reserve(
+//ust// struct ust_channel *channel, struct ust_buffer *buf,
+//ust// struct ltt_reserve_switch_offsets *offsets, size_t data_size,
+//ust// u64 *tsc, unsigned int *rflags, int largest_align)
+//ust// {
+//ust// offsets->begin = local_read(&buf->offset);
+//ust// offsets->old = offsets->begin;
+//ust// offsets->begin_switch = 0;
+//ust// offsets->end_switch_current = 0;
+//ust// offsets->end_switch_old = 0;
+//ust//
+//ust// *tsc = trace_clock_read64();
+//ust// if (last_tsc_overflow(buf, *tsc))
+//ust// *rflags = LTT_RFLAG_ID_SIZE_TSC;
+//ust//
+//ust// if (SUBBUF_OFFSET(offsets->begin, buf->chan) == 0) {
+//ust// offsets->begin_switch = 1; /* For offsets->begin */
+//ust// } else {
+//ust// offsets->size = ust_get_header_size(channel,
+//ust// offsets->begin, data_size,
+//ust// &offsets->before_hdr_pad, *rflags);
+//ust// offsets->size += ltt_align(offsets->begin + offsets->size,
+//ust// largest_align)
+//ust// + data_size;
+//ust// if ((SUBBUF_OFFSET(offsets->begin, buf->chan) + offsets->size)
+//ust// > buf->chan->subbuf_size) {
+//ust// offsets->end_switch_old = 1; /* For offsets->old */
+//ust// offsets->begin_switch = 1; /* For offsets->begin */
+//ust// }
+//ust// }
+//ust// if (offsets->begin_switch) {
+//ust// long subbuf_index;
+//ust//
+//ust// if (offsets->end_switch_old)
+//ust// offsets->begin = SUBBUF_ALIGN(offsets->begin,
+//ust// buf->chan);
+//ust// offsets->begin = offsets->begin + ltt_subbuffer_header_size();
+//ust// /* Test new buffer integrity */
+//ust// subbuf_index = SUBBUF_INDEX(offsets->begin, buf->chan);
+//ust// offsets->reserve_commit_diff =
+//ust// (BUFFER_TRUNC(offsets->begin, buf->chan)
+//ust// >> channel->n_subbufs_order)
+//ust// - (local_read(&buf->commit_count[subbuf_index])
+//ust// & channel->commit_count_mask);
+//ust// if (offsets->reserve_commit_diff == 0) {
+//ust// long consumed;
+//ust//
+//ust// consumed = atomic_long_read(&buf->consumed);
+//ust//
+//ust// /* Next buffer not corrupted. */
+//ust// if (!channel->overwrite &&
+//ust// (SUBBUF_TRUNC(offsets->begin, buf->chan)
+//ust// - SUBBUF_TRUNC(consumed, buf->chan))
+//ust// >= channel->alloc_size) {
+//ust//
+//ust// long consumed_idx = SUBBUF_INDEX(consumed, buf->chan);
+//ust// long commit_count = local_read(&buf->commit_count[consumed_idx]);
+//ust// if(((commit_count - buf->chan->subbuf_size) & channel->commit_count_mask) - (BUFFER_TRUNC(consumed, buf->chan) >> channel->n_subbufs_order) != 0) {
+//ust// WARN("Event dropped. Caused by non-committed event.");
+//ust// }
+//ust// else {
+//ust// WARN("Event dropped. Caused by non-consumed buffer.");
+//ust// }
+//ust// /*
+//ust// * We do not overwrite non consumed buffers
+//ust// * and we are full : event is lost.
+//ust// */
+//ust// local_inc(&buf->events_lost);
+//ust// return -1;
+//ust// } else {
+//ust// /*
+//ust// * next buffer not corrupted, we are either in
+//ust// * overwrite mode or the buffer is not full.
+//ust// * It's safe to write in this new subbuffer.
+//ust// */
+//ust// }
+//ust// } else {
+//ust// /*
+//ust// * Next subbuffer corrupted. Force pushing reader even
+//ust// * in normal mode. It's safe to write in this new
+//ust// * subbuffer.
+//ust// */
+//ust// }
+//ust// offsets->size = ust_get_header_size(channel,
+//ust// offsets->begin, data_size,
+//ust// &offsets->before_hdr_pad, *rflags);
+//ust// offsets->size += ltt_align(offsets->begin + offsets->size,
+//ust// largest_align)
+//ust// + data_size;
+//ust// if ((SUBBUF_OFFSET(offsets->begin, buf->chan) + offsets->size)
+//ust// > buf->chan->subbuf_size) {
+//ust// /*
+//ust// * Event too big for subbuffers, report error, don't
+//ust// * complete the sub-buffer switch.
+//ust// */
+//ust// local_inc(&buf->events_lost);
+//ust// return -1;
+//ust// } else {
+//ust// /*
+//ust// * We just made a successful buffer switch and the event
+//ust// * fits in the new subbuffer. Let's write.
+//ust// */
+//ust// }
+//ust// } else {
+//ust// /*
+//ust// * Event fits in the current buffer and we are not on a switch
+//ust// * boundary. It's safe to write.
+//ust// */
+//ust// }
+//ust// offsets->end = offsets->begin + offsets->size;
+//ust//
+//ust// if ((SUBBUF_OFFSET(offsets->end, buf->chan)) == 0) {
+//ust// /*
+//ust// * The offset_end will fall at the very beginning of the next
+//ust// * subbuffer.
+//ust// */
+//ust// offsets->end_switch_current = 1; /* For offsets->begin */
+//ust// }
+//ust// return 0;
+//ust// }
+//ust//
+//ust// /*
+//ust// * Returns :
+//ust// * 0 if ok
+//ust// * !0 if execution must be aborted.
+//ust// */
+//ust// static inline int ltt_relay_try_switch(
+//ust// enum force_switch_mode mode,
+//ust// struct ust_channel *channel,
+//ust// struct ust_buffer *buf,
+//ust// struct ltt_reserve_switch_offsets *offsets,
+//ust// u64 *tsc)
+//ust// {
+//ust// long subbuf_index;
+//ust//
+//ust// offsets->begin = local_read(&buf->offset);
+//ust// offsets->old = offsets->begin;
+//ust// offsets->begin_switch = 0;
+//ust// offsets->end_switch_old = 0;
+//ust//
+//ust// *tsc = trace_clock_read64();
+//ust//
+//ust// if (SUBBUF_OFFSET(offsets->begin, buf->chan) != 0) {
+//ust// offsets->begin = SUBBUF_ALIGN(offsets->begin, buf->chan);
+//ust// offsets->end_switch_old = 1;
+//ust// } else {
+//ust// /* we do not have to switch : buffer is empty */
+//ust// return -1;
+//ust// }
+//ust// if (mode == FORCE_ACTIVE)
+//ust// offsets->begin += ltt_subbuffer_header_size();
+//ust// /*
+//ust// * Always begin_switch in FORCE_ACTIVE mode.
+//ust// * Test new buffer integrity
+//ust// */
+//ust// subbuf_index = SUBBUF_INDEX(offsets->begin, buf->chan);
+//ust// offsets->reserve_commit_diff =
+//ust// (BUFFER_TRUNC(offsets->begin, buf->chan)
+//ust// >> channel->n_subbufs_order)
+//ust// - (local_read(&buf->commit_count[subbuf_index])
+//ust// & channel->commit_count_mask);
+//ust// if (offsets->reserve_commit_diff == 0) {
+//ust// /* Next buffer not corrupted. */
+//ust// if (mode == FORCE_ACTIVE
+//ust// && !channel->overwrite
+//ust// && offsets->begin - atomic_long_read(&buf->consumed)
+//ust// >= channel->alloc_size) {
+//ust// /*
+//ust// * We do not overwrite non consumed buffers and we are
+//ust// * full : ignore switch while tracing is active.
+//ust// */
+//ust// return -1;
+//ust// }
+//ust// } else {
+//ust// /*
+//ust// * Next subbuffer corrupted. Force pushing reader even in normal
+//ust// * mode
+//ust// */
+//ust// }
+//ust// offsets->end = offsets->begin;
+//ust// return 0;
+//ust// }
+//ust//
+//ust// static inline void ltt_reserve_push_reader(
+//ust// struct ust_channel *channel,
+//ust// struct ust_buffer *buf,
+//ust// struct ltt_reserve_switch_offsets *offsets)
+//ust// {
+//ust// long consumed_old, consumed_new;
+//ust//
+//ust// do {
+//ust// consumed_old = atomic_long_read(&buf->consumed);
+//ust// /*
+//ust// * If buffer is in overwrite mode, push the reader consumed
+//ust// * count if the write position has reached it and we are not
+//ust// * at the first iteration (don't push the reader farther than
+//ust// * the writer). This operation can be done concurrently by many
+//ust// * writers in the same buffer, the writer being at the farthest
+//ust// * write position sub-buffer index in the buffer being the one
+//ust// * which will win this loop.
+//ust// * If the buffer is not in overwrite mode, pushing the reader
+//ust// * only happens if a sub-buffer is corrupted.
+//ust// */
+//ust// if ((SUBBUF_TRUNC(offsets->end-1, buf->chan)
+//ust// - SUBBUF_TRUNC(consumed_old, buf->chan))
+//ust// >= channel->alloc_size)
+//ust// consumed_new = SUBBUF_ALIGN(consumed_old, buf->chan);
+//ust// else {
+//ust// consumed_new = consumed_old;
+//ust// break;
+//ust// }
+//ust// } while (atomic_long_cmpxchg(&buf->consumed, consumed_old,
+//ust// consumed_new) != consumed_old);
+//ust//
+//ust// if (consumed_old != consumed_new) {
+//ust// /*
+//ust// * Reader pushed : we are the winner of the push, we can
+//ust// * therefore reequilibrate reserve and commit. Atomic increment
+//ust// * of the commit count permits other writers to play around
+//ust// * with this variable before us. We keep track of
+//ust// * corrupted_subbuffers even in overwrite mode :
+//ust// * we never want to write over a non completely committed
+//ust// * sub-buffer : possible causes : the buffer size is too low
+//ust// * compared to the unordered data input, or there is a writer
+//ust// * that died between the reserve and the commit.
+//ust// */
+//ust// if (offsets->reserve_commit_diff) {
+//ust// /*
+//ust// * We have to alter the sub-buffer commit count.
+//ust// * We do not deliver the previous subbuffer, given it
+//ust// * was either corrupted or not consumed (overwrite
+//ust// * mode).
+//ust// */
+//ust// local_add(offsets->reserve_commit_diff,
+//ust// &buf->commit_count[
+//ust// SUBBUF_INDEX(offsets->begin,
+//ust// buf->chan)]);
+//ust// if (!channel->overwrite
+//ust// || offsets->reserve_commit_diff
+//ust// != channel->subbuf_size) {
+//ust// /*
+//ust// * The reserve commit diff was not subbuf_size :
+//ust// * it means the subbuffer was partly written to
+//ust// * and is therefore corrupted. If it is multiple
+//ust// * of subbuffer size and we are in flight
+//ust// * recorder mode, we are skipping over a whole
+//ust// * subbuffer.
+//ust// */
+//ust// local_inc(&buf->corrupted_subbuffers);
+//ust// }
+//ust// }
+//ust// }
+//ust// }
+//ust//
+//ust// /**
+//ust// * ltt_relay_reserve_slot - Atomic slot reservation in a LTTng buffer.
+//ust// * @trace: the trace structure to log to.
+//ust// * @ltt_channel: channel structure
+//ust// * @transport_data: data structure specific to ltt relay
+//ust// * @data_size: size of the variable length data to log.
+//ust// * @slot_size: pointer to total size of the slot (out)
+//ust// * @buf_offset : pointer to reserved buffer offset (out)
+//ust// * @tsc: pointer to the tsc at the slot reservation (out)
+//ust// * @cpu: cpuid
+//ust// *
+//ust// * Return : -ENOSPC if not enough space, else returns 0.
+//ust// * It will take care of sub-buffer switching.
+//ust// */
+//ust// static notrace int ltt_relay_reserve_slot(struct ust_trace *trace,
+//ust// struct ust_channel *channel, void **transport_data,
+//ust// size_t data_size, size_t *slot_size, long *buf_offset, u64 *tsc,
+//ust// unsigned int *rflags, int largest_align, int cpu)
+//ust// {
+//ust// struct ust_buffer *buf = *transport_data = channel->buf[cpu];
+//ust// struct ltt_reserve_switch_offsets offsets;
+//ust//
+//ust// offsets.reserve_commit_diff = 0;
+//ust// offsets.size = 0;
+//ust//
+//ust// /*
+//ust// * Perform retryable operations.
+//ust// */
+//ust// if (ltt_nesting > 4) {
+//ust// local_inc(&buf->events_lost);
+//ust// return -EPERM;
+//ust// }
+//ust// do {
+//ust// if (ltt_relay_try_reserve(channel, buf, &offsets, data_size, tsc, rflags,
+//ust// largest_align))
+//ust// return -ENOSPC;
+//ust// } while (local_cmpxchg(&buf->offset, offsets.old,
+//ust// offsets.end) != offsets.old);
+//ust//
+//ust// /*
+//ust// * Atomically update last_tsc. This update races against concurrent
+//ust// * atomic updates, but the race will always cause supplementary full TSC
+//ust// * events, never the opposite (missing a full TSC event when it would be
+//ust// * needed).
+//ust// */
+//ust// save_last_tsc(buf, *tsc);
+//ust//
+//ust// /*
+//ust// * Push the reader if necessary
+//ust// */
+//ust// ltt_reserve_push_reader(channel, buf, &offsets);
+//ust//
+//ust// /*
+//ust// * Switch old subbuffer if needed.
+//ust// */
+//ust// if (offsets.end_switch_old)
+//ust// ltt_reserve_switch_old_subbuf(channel, buf, &offsets, tsc);
+//ust//
+//ust// /*
+//ust// * Populate new subbuffer.
+//ust// */
+//ust// if (offsets.begin_switch)
+//ust// ltt_reserve_switch_new_subbuf(channel, buf, &offsets, tsc);
+//ust//
+//ust// if (offsets.end_switch_current)
+//ust// ltt_reserve_end_switch_current(channel, buf, &offsets, tsc);
+//ust//
+//ust// *slot_size = offsets.size;
+//ust// *buf_offset = offsets.begin + offsets.before_hdr_pad;
+//ust// return 0;
+//ust// }
+//ust//
+//ust// /*
+//ust// * Force a sub-buffer switch for a per-cpu buffer. This operation is
+//ust// * completely reentrant : can be called while tracing is active with
+//ust// * absolutely no lock held.
+//ust// *
+//ust// * Note, however, that as a local_cmpxchg is used for some atomic
+//ust// * operations, this function must be called from the CPU which owns the buffer
+//ust// * for a ACTIVE flush.
+//ust// */
+//ust// static notrace void ltt_force_switch(struct ust_buffer *buf,
+//ust// enum force_switch_mode mode)
+//ust// {
+//ust// struct ust_channel *channel = buf->chan;
+//ust// struct ltt_reserve_switch_offsets offsets;
+//ust// u64 tsc;
+//ust//
+//ust// offsets.reserve_commit_diff = 0;
+//ust// offsets.size = 0;
+//ust//
+//ust// /*
+//ust// * Perform retryable operations.
+//ust// */
+//ust// do {
+//ust// if (ltt_relay_try_switch(mode, channel, buf, &offsets, &tsc))
+//ust// return;
+//ust// } while (local_cmpxchg(&buf->offset, offsets.old,
+//ust// offsets.end) != offsets.old);
+//ust//
+//ust// /*
+//ust// * Atomically update last_tsc. This update races against concurrent
+//ust// * atomic updates, but the race will always cause supplementary full TSC
+//ust// * events, never the opposite (missing a full TSC event when it would be
+//ust// * needed).
+//ust// */
+//ust// save_last_tsc(buf, tsc);
+//ust//
+//ust// /*
+//ust// * Push the reader if necessary
+//ust// */
+//ust// if (mode == FORCE_ACTIVE)
+//ust// ltt_reserve_push_reader(channel, buf, &offsets);
+//ust//
+//ust// /*
+//ust// * Switch old subbuffer if needed.
+//ust// */
+//ust// if (offsets.end_switch_old)
+//ust// ltt_reserve_switch_old_subbuf(channel, buf, &offsets, &tsc);
+//ust//
+//ust// /*
+//ust// * Populate new subbuffer.
+//ust// */
+//ust// if (mode == FORCE_ACTIVE)
+//ust// ltt_reserve_switch_new_subbuf(channel, buf, &offsets, &tsc);
+//ust// }
/*
- * Returns :
- * 0 if ok
- * !0 if execution must be aborted.
+ * ltt_reserve_switch_old_subbuf: switch old subbuffer
+ *
+ * Concurrency safe because we are the last and only thread to alter this
+ * sub-buffer. As long as it is not delivered and read, no other thread can
+ * alter the offset, alter the reserve_count or call the
+ * client_buffer_end_callback on this sub-buffer.
+ *
+ * The only remaining threads could be the ones with pending commits. They will
+ * have to do the deliver themselves. Not concurrency safe in overwrite mode.
+ * We detect corrupted subbuffers with commit and reserve counts. We keep a
+ * corrupted sub-buffers count and push the readers across these sub-buffers.
+ *
+ * Not concurrency safe if a writer is stalled in a subbuffer and another writer
+ * switches in, finding out it's corrupted. The result will be than the old
+ * (uncommited) subbuffer will be declared corrupted, and that the new subbuffer
+ * will be declared corrupted too because of the commit count adjustment.
+ *
+ * Note : offset_old should never be 0 here.
*/
-static inline int ltt_relay_try_reserve(
- struct ust_channel *channel, struct ust_buffer *buf,
- struct ltt_reserve_switch_offsets *offsets, size_t data_size,
- u64 *tsc, unsigned int *rflags, int largest_align)
+static void ltt_reserve_switch_old_subbuf(
+ struct ust_channel *chan, struct ust_buffer *buf,
+ struct ltt_reserve_switch_offsets *offsets, u64 *tsc)
{
- offsets->begin = local_read(&buf->offset);
- offsets->old = offsets->begin;
- offsets->begin_switch = 0;
- offsets->end_switch_current = 0;
- offsets->end_switch_old = 0;
+ long oldidx = SUBBUF_INDEX(offsets->old - 1, chan);
+ long commit_count, padding_size;
- *tsc = trace_clock_read64();
- if (last_tsc_overflow(buf, *tsc))
- *rflags = LTT_RFLAG_ID_SIZE_TSC;
+ padding_size = chan->subbuf_size
+ - (SUBBUF_OFFSET(offsets->old - 1, chan) + 1);
+ ltt_buffer_end(buf, *tsc, offsets->old, oldidx);
- if (SUBBUF_OFFSET(offsets->begin, buf->chan) == 0) {
- offsets->begin_switch = 1; /* For offsets->begin */
- } else {
- offsets->size = ust_get_header_size(channel,
- offsets->begin, data_size,
- &offsets->before_hdr_pad, *rflags);
- offsets->size += ltt_align(offsets->begin + offsets->size,
- largest_align)
- + data_size;
- if ((SUBBUF_OFFSET(offsets->begin, buf->chan) + offsets->size)
- > buf->chan->subbuf_size) {
- offsets->end_switch_old = 1; /* For offsets->old */
- offsets->begin_switch = 1; /* For offsets->begin */
- }
- }
- if (offsets->begin_switch) {
- long subbuf_index;
+ /*
+ * Must write slot data before incrementing commit count.
+ * This compiler barrier is upgraded into a smp_wmb() by the IPI
+ * sent by get_subbuf() when it does its smp_rmb().
+ */
+ barrier();
+ local_add(padding_size,
+ &buf->commit_count[oldidx].cc);
+ commit_count = local_read(&buf->commit_count[oldidx].cc);
+ ltt_check_deliver(chan, buf, offsets->old - 1, commit_count, oldidx);
+ ltt_write_commit_counter(buf, oldidx,
+ offsets->old, commit_count, padding_size);
+}
- if (offsets->end_switch_old)
- offsets->begin = SUBBUF_ALIGN(offsets->begin,
- buf->chan);
- offsets->begin = offsets->begin + ltt_subbuffer_header_size();
- /* Test new buffer integrity */
- subbuf_index = SUBBUF_INDEX(offsets->begin, buf->chan);
- offsets->reserve_commit_diff =
- (BUFFER_TRUNC(offsets->begin, buf->chan)
- >> channel->n_subbufs_order)
- - (local_read(&buf->commit_count[subbuf_index])
- & channel->commit_count_mask);
- if (offsets->reserve_commit_diff == 0) {
- long consumed;
+/*
+ * ltt_reserve_switch_new_subbuf: Populate new subbuffer.
+ *
+ * This code can be executed unordered : writers may already have written to the
+ * sub-buffer before this code gets executed, caution. The commit makes sure
+ * that this code is executed before the deliver of this sub-buffer.
+ */
+static void ltt_reserve_switch_new_subbuf(
+ struct ust_channel *chan, struct ust_buffer *buf,
+ struct ltt_reserve_switch_offsets *offsets, u64 *tsc)
+{
+ long beginidx = SUBBUF_INDEX(offsets->begin, chan);
+ long commit_count;
- consumed = atomic_long_read(&buf->consumed);
+ ltt_buffer_begin(buf, *tsc, beginidx);
- /* Next buffer not corrupted. */
- if (!channel->overwrite &&
- (SUBBUF_TRUNC(offsets->begin, buf->chan)
- - SUBBUF_TRUNC(consumed, buf->chan))
- >= channel->alloc_size) {
-
- long consumed_idx = SUBBUF_INDEX(consumed, buf->chan);
- long commit_count = local_read(&buf->commit_count[consumed_idx]);
- if(((commit_count - buf->chan->subbuf_size) & channel->commit_count_mask) - (BUFFER_TRUNC(consumed, buf->chan) >> channel->n_subbufs_order) != 0) {
- WARN("Event dropped. Caused by non-committed event.");
- }
- else {
- WARN("Event dropped. Caused by non-consumed buffer.");
- }
- /*
- * We do not overwrite non consumed buffers
- * and we are full : event is lost.
- */
- local_inc(&buf->events_lost);
- return -1;
- } else {
- /*
- * next buffer not corrupted, we are either in
- * overwrite mode or the buffer is not full.
- * It's safe to write in this new subbuffer.
- */
- }
- } else {
- /*
- * Next subbuffer corrupted. Force pushing reader even
- * in normal mode. It's safe to write in this new
- * subbuffer.
- */
- }
- offsets->size = ust_get_header_size(channel,
- offsets->begin, data_size,
- &offsets->before_hdr_pad, *rflags);
- offsets->size += ltt_align(offsets->begin + offsets->size,
- largest_align)
- + data_size;
- if ((SUBBUF_OFFSET(offsets->begin, buf->chan) + offsets->size)
- > buf->chan->subbuf_size) {
- /*
- * Event too big for subbuffers, report error, don't
- * complete the sub-buffer switch.
- */
- local_inc(&buf->events_lost);
- return -1;
- } else {
- /*
- * We just made a successful buffer switch and the event
- * fits in the new subbuffer. Let's write.
- */
- }
- } else {
- /*
- * Event fits in the current buffer and we are not on a switch
- * boundary. It's safe to write.
- */
- }
- offsets->end = offsets->begin + offsets->size;
+ /*
+ * Must write slot data before incrementing commit count.
+ * This compiler barrier is upgraded into a smp_wmb() by the IPI
+ * sent by get_subbuf() when it does its smp_rmb().
+ */
+ barrier();
+ local_add(ltt_subbuffer_header_size(),
+ &buf->commit_count[beginidx].cc);
+ commit_count = local_read(&buf->commit_count[beginidx].cc);
+ /* Check if the written buffer has to be delivered */
+ ltt_check_deliver(chan, buf, offsets->begin, commit_count, beginidx);
+ ltt_write_commit_counter(buf, beginidx,
+ offsets->begin, commit_count, ltt_subbuffer_header_size());
+}
- if ((SUBBUF_OFFSET(offsets->end, buf->chan)) == 0) {
- /*
- * The offset_end will fall at the very beginning of the next
- * subbuffer.
- */
- offsets->end_switch_current = 1; /* For offsets->begin */
- }
- return 0;
+/*
+ * ltt_reserve_end_switch_current: finish switching current subbuffer
+ *
+ * Concurrency safe because we are the last and only thread to alter this
+ * sub-buffer. As long as it is not delivered and read, no other thread can
+ * alter the offset, alter the reserve_count or call the
+ * client_buffer_end_callback on this sub-buffer.
+ *
+ * The only remaining threads could be the ones with pending commits. They will
+ * have to do the deliver themselves. Not concurrency safe in overwrite mode.
+ * We detect corrupted subbuffers with commit and reserve counts. We keep a
+ * corrupted sub-buffers count and push the readers across these sub-buffers.
+ *
+ * Not concurrency safe if a writer is stalled in a subbuffer and another writer
+ * switches in, finding out it's corrupted. The result will be than the old
+ * (uncommited) subbuffer will be declared corrupted, and that the new subbuffer
+ * will be declared corrupted too because of the commit count adjustment.
+ */
+static void ltt_reserve_end_switch_current(
+ struct ust_channel *chan,
+ struct ust_buffer *buf,
+ struct ltt_reserve_switch_offsets *offsets, u64 *tsc)
+{
+ long endidx = SUBBUF_INDEX(offsets->end - 1, chan);
+ long commit_count, padding_size;
+
+ padding_size = chan->subbuf_size
+ - (SUBBUF_OFFSET(offsets->end - 1, chan) + 1);
+
+ ltt_buffer_end(buf, *tsc, offsets->end, endidx);
+
+ /*
+ * Must write slot data before incrementing commit count.
+ * This compiler barrier is upgraded into a smp_wmb() by the IPI
+ * sent by get_subbuf() when it does its smp_rmb().
+ */
+ barrier();
+ local_add(padding_size,
+ &buf->commit_count[endidx].cc);
+ commit_count = local_read(&buf->commit_count[endidx].cc);
+ ltt_check_deliver(chan, buf,
+ offsets->end - 1, commit_count, endidx);
+ ltt_write_commit_counter(buf, endidx,
+ offsets->end, commit_count, padding_size);
}
/*
* 0 if ok
* !0 if execution must be aborted.
*/
-static inline int ltt_relay_try_switch(
+static int ltt_relay_try_switch_slow(
enum force_switch_mode mode,
- struct ust_channel *channel,
+ struct ust_channel *chan,
struct ust_buffer *buf,
struct ltt_reserve_switch_offsets *offsets,
u64 *tsc)
{
long subbuf_index;
+ long reserve_commit_diff;
offsets->begin = local_read(&buf->offset);
offsets->old = offsets->begin;
* Test new buffer integrity
*/
subbuf_index = SUBBUF_INDEX(offsets->begin, buf->chan);
- offsets->reserve_commit_diff =
+ reserve_commit_diff =
(BUFFER_TRUNC(offsets->begin, buf->chan)
- >> channel->n_subbufs_order)
- - (local_read(&buf->commit_count[subbuf_index])
- & channel->commit_count_mask);
- if (offsets->reserve_commit_diff == 0) {
+ >> chan->n_subbufs_order)
+ - (local_read(&buf->commit_count[subbuf_index].cc_sb)
+ & chan->commit_count_mask);
+ if (reserve_commit_diff == 0) {
/* Next buffer not corrupted. */
if (mode == FORCE_ACTIVE
- && !channel->overwrite
+ && !chan->overwrite
&& offsets->begin - atomic_long_read(&buf->consumed)
- >= channel->alloc_size) {
+ >= chan->alloc_size) {
/*
* We do not overwrite non consumed buffers and we are
* full : ignore switch while tracing is active.
return 0;
}
-static inline void ltt_reserve_push_reader(
- struct ust_channel *channel,
- struct ust_buffer *buf,
- struct ltt_reserve_switch_offsets *offsets)
-{
- long consumed_old, consumed_new;
-
- do {
- consumed_old = atomic_long_read(&buf->consumed);
- /*
- * If buffer is in overwrite mode, push the reader consumed
- * count if the write position has reached it and we are not
- * at the first iteration (don't push the reader farther than
- * the writer). This operation can be done concurrently by many
- * writers in the same buffer, the writer being at the farthest
- * write position sub-buffer index in the buffer being the one
- * which will win this loop.
- * If the buffer is not in overwrite mode, pushing the reader
- * only happens if a sub-buffer is corrupted.
- */
- if ((SUBBUF_TRUNC(offsets->end-1, buf->chan)
- - SUBBUF_TRUNC(consumed_old, buf->chan))
- >= channel->alloc_size)
- consumed_new = SUBBUF_ALIGN(consumed_old, buf->chan);
- else {
- consumed_new = consumed_old;
- break;
- }
- } while (atomic_long_cmpxchg(&buf->consumed, consumed_old,
- consumed_new) != consumed_old);
-
- if (consumed_old != consumed_new) {
- /*
- * Reader pushed : we are the winner of the push, we can
- * therefore reequilibrate reserve and commit. Atomic increment
- * of the commit count permits other writers to play around
- * with this variable before us. We keep track of
- * corrupted_subbuffers even in overwrite mode :
- * we never want to write over a non completely committed
- * sub-buffer : possible causes : the buffer size is too low
- * compared to the unordered data input, or there is a writer
- * that died between the reserve and the commit.
- */
- if (offsets->reserve_commit_diff) {
- /*
- * We have to alter the sub-buffer commit count.
- * We do not deliver the previous subbuffer, given it
- * was either corrupted or not consumed (overwrite
- * mode).
- */
- local_add(offsets->reserve_commit_diff,
- &buf->commit_count[
- SUBBUF_INDEX(offsets->begin,
- buf->chan)]);
- if (!channel->overwrite
- || offsets->reserve_commit_diff
- != channel->subbuf_size) {
- /*
- * The reserve commit diff was not subbuf_size :
- * it means the subbuffer was partly written to
- * and is therefore corrupted. If it is multiple
- * of subbuffer size and we are in flight
- * recorder mode, we are skipping over a whole
- * subbuffer.
- */
- local_inc(&buf->corrupted_subbuffers);
- }
- }
- }
-}
-
-
-/*
- * ltt_reserve_switch_old_subbuf: switch old subbuffer
- *
- * Concurrency safe because we are the last and only thread to alter this
- * sub-buffer. As long as it is not delivered and read, no other thread can
- * alter the offset, alter the reserve_count or call the
- * client_buffer_end_callback on this sub-buffer.
- *
- * The only remaining threads could be the ones with pending commits. They will
- * have to do the deliver themselves. Not concurrency safe in overwrite mode.
- * We detect corrupted subbuffers with commit and reserve counts. We keep a
- * corrupted sub-buffers count and push the readers across these sub-buffers.
- *
- * Not concurrency safe if a writer is stalled in a subbuffer and another writer
- * switches in, finding out it's corrupted. The result will be than the old
- * (uncommited) subbuffer will be declared corrupted, and that the new subbuffer
- * will be declared corrupted too because of the commit count adjustment.
- *
- * Note : offset_old should never be 0 here.
- */
-static inline void ltt_reserve_switch_old_subbuf(
- struct ust_channel *channel,
- struct ust_buffer *buf,
- struct ltt_reserve_switch_offsets *offsets, u64 *tsc)
-{
- long oldidx = SUBBUF_INDEX(offsets->old - 1, channel);
-
- channel->buffer_end(buf, *tsc, offsets->old, oldidx);
- /* Must write buffer end before incrementing commit count */
- smp_wmb();
- offsets->commit_count =
- local_add_return(channel->subbuf_size
- - (SUBBUF_OFFSET(offsets->old - 1, channel)
- + 1),
- &buf->commit_count[oldidx]);
- if ((BUFFER_TRUNC(offsets->old - 1, channel)
- >> channel->n_subbufs_order)
- - ((offsets->commit_count - channel->subbuf_size)
- & channel->commit_count_mask) == 0)
- ltt_deliver(buf, oldidx, offsets->commit_count);
-}
-
/*
- * ltt_reserve_switch_new_subbuf: Populate new subbuffer.
- *
- * This code can be executed unordered : writers may already have written to the
- * sub-buffer before this code gets executed, caution. The commit makes sure
- * that this code is executed before the deliver of this sub-buffer.
- */
-static /*inline*/ void ltt_reserve_switch_new_subbuf(
- struct ust_channel *channel,
- struct ust_buffer *buf,
- struct ltt_reserve_switch_offsets *offsets, u64 *tsc)
-{
- long beginidx = SUBBUF_INDEX(offsets->begin, channel);
-
- channel->buffer_begin(buf, *tsc, beginidx);
- /* Must write buffer end before incrementing commit count */
- smp_wmb();
- offsets->commit_count = local_add_return(ltt_subbuffer_header_size(),
- &buf->commit_count[beginidx]);
- /* Check if the written buffer has to be delivered */
- if ((BUFFER_TRUNC(offsets->begin, channel)
- >> channel->n_subbufs_order)
- - ((offsets->commit_count - channel->subbuf_size)
- & channel->commit_count_mask) == 0)
- ltt_deliver(buf, beginidx, offsets->commit_count);
-}
-
-
-/*
- * ltt_reserve_end_switch_current: finish switching current subbuffer
- *
- * Concurrency safe because we are the last and only thread to alter this
- * sub-buffer. As long as it is not delivered and read, no other thread can
- * alter the offset, alter the reserve_count or call the
- * client_buffer_end_callback on this sub-buffer.
- *
- * The only remaining threads could be the ones with pending commits. They will
- * have to do the deliver themselves. Not concurrency safe in overwrite mode.
- * We detect corrupted subbuffers with commit and reserve counts. We keep a
- * corrupted sub-buffers count and push the readers across these sub-buffers.
- *
- * Not concurrency safe if a writer is stalled in a subbuffer and another writer
- * switches in, finding out it's corrupted. The result will be than the old
- * (uncommited) subbuffer will be declared corrupted, and that the new subbuffer
- * will be declared corrupted too because of the commit count adjustment.
- */
-static inline void ltt_reserve_end_switch_current(
- struct ust_channel *channel,
- struct ust_buffer *buf,
- struct ltt_reserve_switch_offsets *offsets, u64 *tsc)
-{
- long endidx = SUBBUF_INDEX(offsets->end - 1, channel);
-
- channel->buffer_end(buf, *tsc, offsets->end, endidx);
- /* Must write buffer begin before incrementing commit count */
- smp_wmb();
- offsets->commit_count =
- local_add_return(channel->subbuf_size
- - (SUBBUF_OFFSET(offsets->end - 1, channel)
- + 1),
- &buf->commit_count[endidx]);
- if ((BUFFER_TRUNC(offsets->end - 1, channel)
- >> channel->n_subbufs_order)
- - ((offsets->commit_count - channel->subbuf_size)
- & channel->commit_count_mask) == 0)
- ltt_deliver(buf, endidx, offsets->commit_count);
-}
-
-/**
- * ltt_relay_reserve_slot - Atomic slot reservation in a LTTng buffer.
- * @trace: the trace structure to log to.
- * @ltt_channel: channel structure
- * @transport_data: data structure specific to ltt relay
- * @data_size: size of the variable length data to log.
- * @slot_size: pointer to total size of the slot (out)
- * @buf_offset : pointer to reserved buffer offset (out)
- * @tsc: pointer to the tsc at the slot reservation (out)
- * @cpu: cpuid
+ * Force a sub-buffer switch for a per-cpu buffer. This operation is
+ * completely reentrant : can be called while tracing is active with
+ * absolutely no lock held.
*
- * Return : -ENOSPC if not enough space, else returns 0.
- * It will take care of sub-buffer switching.
+ * Note, however, that as a local_cmpxchg is used for some atomic
+ * operations, this function must be called from the CPU which owns the buffer
+ * for a ACTIVE flush.
*/
-static notrace int ltt_relay_reserve_slot(struct ltt_trace_struct *trace,
- struct ust_channel *channel, void **transport_data,
- size_t data_size, size_t *slot_size, long *buf_offset, u64 *tsc,
- unsigned int *rflags, int largest_align, int cpu)
+void ltt_force_switch_lockless_slow(struct ust_buffer *buf,
+ enum force_switch_mode mode)
{
- struct ust_buffer *buf = *transport_data = channel->buf[cpu];
+ struct ust_channel *chan = buf->chan;
struct ltt_reserve_switch_offsets offsets;
+ u64 tsc;
- offsets.reserve_commit_diff = 0;
offsets.size = 0;
/*
* Perform retryable operations.
*/
- if (ltt_nesting > 4) {
- local_inc(&buf->events_lost);
- return -EPERM;
- }
do {
- if (ltt_relay_try_reserve(channel, buf, &offsets, data_size, tsc, rflags,
- largest_align))
- return -ENOSPC;
+ if (ltt_relay_try_switch_slow(mode, chan, buf,
+ &offsets, &tsc))
+ return;
} while (local_cmpxchg(&buf->offset, offsets.old,
offsets.end) != offsets.old);
* events, never the opposite (missing a full TSC event when it would be
* needed).
*/
- save_last_tsc(buf, *tsc);
+ save_last_tsc(buf, tsc);
/*
* Push the reader if necessary
*/
- ltt_reserve_push_reader(channel, buf, &offsets);
+ if (mode == FORCE_ACTIVE) {
+ ltt_reserve_push_reader(chan, buf, offsets.end - 1);
+//ust// ltt_clear_noref_flag(chan, buf, SUBBUF_INDEX(offsets.end - 1, chan));
+ }
/*
* Switch old subbuffer if needed.
*/
- if (offsets.end_switch_old)
- ltt_reserve_switch_old_subbuf(channel, buf, &offsets, tsc);
+ if (offsets.end_switch_old) {
+//ust// ltt_clear_noref_flag(rchan, buf, SUBBUF_INDEX(offsets.old - 1, rchan));
+ ltt_reserve_switch_old_subbuf(chan, buf, &offsets, &tsc);
+ }
/*
* Populate new subbuffer.
*/
- if (offsets.begin_switch)
- ltt_reserve_switch_new_subbuf(channel, buf, &offsets, tsc);
+ if (mode == FORCE_ACTIVE)
+ ltt_reserve_switch_new_subbuf(chan, buf, &offsets, &tsc);
+}
- if (offsets.end_switch_current)
- ltt_reserve_end_switch_current(channel, buf, &offsets, tsc);
+/*
+ * Returns :
+ * 0 if ok
+ * !0 if execution must be aborted.
+ */
+static int ltt_relay_try_reserve_slow(struct ust_channel *chan, struct ust_buffer *buf,
+ struct ltt_reserve_switch_offsets *offsets, size_t data_size,
+ u64 *tsc, unsigned int *rflags, int largest_align)
+{
+ long reserve_commit_diff;
- *slot_size = offsets.size;
- *buf_offset = offsets.begin + offsets.before_hdr_pad;
+ offsets->begin = local_read(&buf->offset);
+ offsets->old = offsets->begin;
+ offsets->begin_switch = 0;
+ offsets->end_switch_current = 0;
+ offsets->end_switch_old = 0;
+
+ *tsc = trace_clock_read64();
+ if (last_tsc_overflow(buf, *tsc))
+ *rflags = LTT_RFLAG_ID_SIZE_TSC;
+
+ if (unlikely(SUBBUF_OFFSET(offsets->begin, buf->chan) == 0)) {
+ offsets->begin_switch = 1; /* For offsets->begin */
+ } else {
+ offsets->size = ust_get_header_size(chan,
+ offsets->begin, data_size,
+ &offsets->before_hdr_pad, *rflags);
+ offsets->size += ltt_align(offsets->begin + offsets->size,
+ largest_align)
+ + data_size;
+ if (unlikely((SUBBUF_OFFSET(offsets->begin, buf->chan) +
+ offsets->size) > buf->chan->subbuf_size)) {
+ offsets->end_switch_old = 1; /* For offsets->old */
+ offsets->begin_switch = 1; /* For offsets->begin */
+ }
+ }
+ if (unlikely(offsets->begin_switch)) {
+ long subbuf_index;
+
+ /*
+ * We are typically not filling the previous buffer completely.
+ */
+ if (likely(offsets->end_switch_old))
+ offsets->begin = SUBBUF_ALIGN(offsets->begin,
+ buf->chan);
+ offsets->begin = offsets->begin + ltt_subbuffer_header_size();
+ /* Test new buffer integrity */
+ subbuf_index = SUBBUF_INDEX(offsets->begin, buf->chan);
+ reserve_commit_diff =
+ (BUFFER_TRUNC(offsets->begin, buf->chan)
+ >> chan->n_subbufs_order)
+ - (local_read(&buf->commit_count[subbuf_index].cc_sb)
+ & chan->commit_count_mask);
+ if (likely(reserve_commit_diff == 0)) {
+ /* Next buffer not corrupted. */
+ if (unlikely(!chan->overwrite &&
+ (SUBBUF_TRUNC(offsets->begin, buf->chan)
+ - SUBBUF_TRUNC(atomic_long_read(
+ &buf->consumed),
+ buf->chan))
+ >= chan->alloc_size)) {
+ /*
+ * We do not overwrite non consumed buffers
+ * and we are full : event is lost.
+ */
+ local_inc(&buf->events_lost);
+ return -1;
+ } else {
+ /*
+ * next buffer not corrupted, we are either in
+ * overwrite mode or the buffer is not full.
+ * It's safe to write in this new subbuffer.
+ */
+ }
+ } else {
+ /*
+ * Next subbuffer corrupted. Drop event in normal and
+ * overwrite mode. Caused by either a writer OOPS or
+ * too many nested writes over a reserve/commit pair.
+ */
+ local_inc(&buf->events_lost);
+ return -1;
+ }
+ offsets->size = ust_get_header_size(chan,
+ offsets->begin, data_size,
+ &offsets->before_hdr_pad, *rflags);
+ offsets->size += ltt_align(offsets->begin + offsets->size,
+ largest_align)
+ + data_size;
+ if (unlikely((SUBBUF_OFFSET(offsets->begin, buf->chan)
+ + offsets->size) > buf->chan->subbuf_size)) {
+ /*
+ * Event too big for subbuffers, report error, don't
+ * complete the sub-buffer switch.
+ */
+ local_inc(&buf->events_lost);
+ return -1;
+ } else {
+ /*
+ * We just made a successful buffer switch and the event
+ * fits in the new subbuffer. Let's write.
+ */
+ }
+ } else {
+ /*
+ * Event fits in the current buffer and we are not on a switch
+ * boundary. It's safe to write.
+ */
+ }
+ offsets->end = offsets->begin + offsets->size;
+
+ if (unlikely((SUBBUF_OFFSET(offsets->end, buf->chan)) == 0)) {
+ /*
+ * The offset_end will fall at the very beginning of the next
+ * subbuffer.
+ */
+ offsets->end_switch_current = 1; /* For offsets->begin */
+ }
return 0;
}
-/*
- * Force a sub-buffer switch for a per-cpu buffer. This operation is
- * completely reentrant : can be called while tracing is active with
- * absolutely no lock held.
+/**
+ * ltt_relay_reserve_slot_lockless_slow - Atomic slot reservation in a buffer.
+ * @trace: the trace structure to log to.
+ * @ltt_channel: channel structure
+ * @transport_data: data structure specific to ltt relay
+ * @data_size: size of the variable length data to log.
+ * @slot_size: pointer to total size of the slot (out)
+ * @buf_offset : pointer to reserved buffer offset (out)
+ * @tsc: pointer to the tsc at the slot reservation (out)
+ * @cpu: cpuid
*
- * Note, however, that as a local_cmpxchg is used for some atomic
- * operations, this function must be called from the CPU which owns the buffer
- * for a ACTIVE flush.
+ * Return : -ENOSPC if not enough space, else returns 0.
+ * It will take care of sub-buffer switching.
*/
-static notrace void ltt_force_switch(struct ust_buffer *buf,
- enum force_switch_mode mode)
+int ltt_reserve_slot_lockless_slow(struct ust_trace *trace,
+ struct ust_channel *chan, void **transport_data,
+ size_t data_size, size_t *slot_size, long *buf_offset, u64 *tsc,
+ unsigned int *rflags, int largest_align, int cpu)
{
- struct ust_channel *channel = buf->chan;
+ struct ust_buffer *buf = chan->buf[cpu];
struct ltt_reserve_switch_offsets offsets;
- u64 tsc;
- offsets.reserve_commit_diff = 0;
offsets.size = 0;
- /*
- * Perform retryable operations.
- */
do {
- if (ltt_relay_try_switch(mode, channel, buf, &offsets, &tsc))
- return;
- } while (local_cmpxchg(&buf->offset, offsets.old,
- offsets.end) != offsets.old);
+ if (unlikely(ltt_relay_try_reserve_slow(chan, buf, &offsets,
+ data_size, tsc, rflags, largest_align)))
+ return -ENOSPC;
+ } while (unlikely(local_cmpxchg(&buf->offset, offsets.old,
+ offsets.end) != offsets.old));
/*
* Atomically update last_tsc. This update races against concurrent
* events, never the opposite (missing a full TSC event when it would be
* needed).
*/
- save_last_tsc(buf, tsc);
+ save_last_tsc(buf, *tsc);
/*
* Push the reader if necessary
*/
- if (mode == FORCE_ACTIVE)
- ltt_reserve_push_reader(channel, buf, &offsets);
+ ltt_reserve_push_reader(chan, buf, offsets.end - 1);
+
+ /*
+ * Clear noref flag for this subbuffer.
+ */
+//ust// ltt_clear_noref_flag(chan, buf, SUBBUF_INDEX(offsets.end - 1, chan));
/*
* Switch old subbuffer if needed.
*/
- if (offsets.end_switch_old)
- ltt_reserve_switch_old_subbuf(channel, buf, &offsets, &tsc);
+ if (unlikely(offsets.end_switch_old)) {
+//ust// ltt_clear_noref_flag(chan, buf, SUBBUF_INDEX(offsets.old - 1, chan));
+ ltt_reserve_switch_old_subbuf(chan, buf, &offsets, tsc);
+ }
/*
* Populate new subbuffer.
*/
- if (mode == FORCE_ACTIVE)
- ltt_reserve_switch_new_subbuf(channel, buf, &offsets, &tsc);
+ if (unlikely(offsets.begin_switch))
+ ltt_reserve_switch_new_subbuf(chan, buf, &offsets, tsc);
+
+ if (unlikely(offsets.end_switch_current))
+ ltt_reserve_end_switch_current(chan, buf, &offsets, tsc);
+
+ *slot_size = offsets.size;
+ *buf_offset = offsets.begin + offsets.before_hdr_pad;
+ return 0;
}
static struct ltt_transport ust_relay_transport = {
.finish_channel = ltt_relay_finish_channel,
.remove_channel = ltt_relay_remove_channel,
.wakeup_channel = ltt_relay_async_wakeup_chan,
-// .commit_slot = ltt_relay_commit_slot,
- .reserve_slot = ltt_relay_reserve_slot,
},
};
-/*
- * for flight recording. must be called after relay_commit.
- * This function decrements de subbuffer's lost_size each time the commit count
- * reaches back the reserve offset (module subbuffer size). It is useful for
- * crash dump.
- */
-static /* inline */ void ltt_write_commit_counter(struct ust_buffer *buf,
- struct ust_buffer *ltt_buf,
- long idx, long buf_offset, long commit_count, size_t data_size)
-{
- long offset;
- long commit_seq_old;
-
- offset = buf_offset + data_size;
-
- /*
- * SUBBUF_OFFSET includes commit_count_mask. We can simply
- * compare the offsets within the subbuffer without caring about
- * buffer full/empty mismatch because offset is never zero here
- * (subbuffer header and event headers have non-zero length).
- */
- if (unlikely(SUBBUF_OFFSET(offset - commit_count, buf->chan)))
- return;
-
- commit_seq_old = local_read(<t_buf->commit_seq[idx]);
- while (commit_seq_old < commit_count)
- commit_seq_old = local_cmpxchg(<t_buf->commit_seq[idx],
- commit_seq_old, commit_count);
-}
-
-/*
- * Atomic unordered slot commit. Increments the commit count in the
- * specified sub-buffer, and delivers it if necessary.
- *
- * Parameters:
- *
- * @ltt_channel : channel structure
- * @transport_data: transport-specific data
- * @buf_offset : offset following the event header.
- * @data_size : size of the event data.
- * @slot_size : size of the reserved slot.
- */
-/* FIXME: make this function static inline in the .h! */
-/*static*/ /* inline */ notrace void ltt_commit_slot(
- struct ust_channel *channel,
- void **transport_data, long buf_offset,
- size_t data_size, size_t slot_size)
-{
- struct ust_buffer *buf = *transport_data;
- long offset_end = buf_offset;
- long endidx = SUBBUF_INDEX(offset_end - 1, channel);
- long commit_count;
-
- /* Must write slot data before incrementing commit count */
- smp_wmb();
- commit_count = local_add_return(slot_size,
- &buf->commit_count[endidx]);
- /* Check if all commits have been done */
- if ((BUFFER_TRUNC(offset_end - 1, channel)
- >> channel->n_subbufs_order)
- - ((commit_count - channel->subbuf_size)
- & channel->commit_count_mask) == 0)
- ltt_deliver(buf, endidx, commit_count);
- /*
- * Update lost_size for each commit. It's needed only for extracting
- * ltt buffers from vmcore, after crash.
- */
- ltt_write_commit_counter(buf, buf, endidx,
- buf_offset, commit_count, data_size);
-}
-
-
static char initialized = 0;
void __attribute__((constructor)) init_ustrelay_transport(void)
}
}
-static void __attribute__((destructor)) ltt_relay_exit(void)
+static void __attribute__((destructor)) ust_buffers_exit(void)
{
ltt_transport_unregister(&ust_relay_transport);
}
+
+size_t ltt_write_event_header_slow(struct ust_trace *trace,
+ struct ust_channel *channel,
+ struct ust_buffer *buf, long buf_offset,
+ u16 eID, u32 event_size,
+ u64 tsc, unsigned int rflags)
+{
+ struct ltt_event_header header;
+ u16 small_size;
+
+ switch (rflags) {
+ case LTT_RFLAG_ID_SIZE_TSC:
+ header.id_time = 29 << LTT_TSC_BITS;
+ break;
+ case LTT_RFLAG_ID_SIZE:
+ header.id_time = 30 << LTT_TSC_BITS;
+ break;
+ case LTT_RFLAG_ID:
+ header.id_time = 31 << LTT_TSC_BITS;
+ break;
+ }
+
+ header.id_time |= (u32)tsc & LTT_TSC_MASK;
+ ust_buffers_write(buf, buf_offset, &header, sizeof(header));
+ buf_offset += sizeof(header);
+
+ switch (rflags) {
+ case LTT_RFLAG_ID_SIZE_TSC:
+ small_size = (u16)min_t(u32, event_size, LTT_MAX_SMALL_SIZE);
+ ust_buffers_write(buf, buf_offset,
+ &eID, sizeof(u16));
+ buf_offset += sizeof(u16);
+ ust_buffers_write(buf, buf_offset,
+ &small_size, sizeof(u16));
+ buf_offset += sizeof(u16);
+ if (small_size == LTT_MAX_SMALL_SIZE) {
+ ust_buffers_write(buf, buf_offset,
+ &event_size, sizeof(u32));
+ buf_offset += sizeof(u32);
+ }
+ buf_offset += ltt_align(buf_offset, sizeof(u64));
+ ust_buffers_write(buf, buf_offset,
+ &tsc, sizeof(u64));
+ buf_offset += sizeof(u64);
+ break;
+ case LTT_RFLAG_ID_SIZE:
+ small_size = (u16)min_t(u32, event_size, LTT_MAX_SMALL_SIZE);
+ ust_buffers_write(buf, buf_offset,
+ &eID, sizeof(u16));
+ buf_offset += sizeof(u16);
+ ust_buffers_write(buf, buf_offset,
+ &small_size, sizeof(u16));
+ buf_offset += sizeof(u16);
+ if (small_size == LTT_MAX_SMALL_SIZE) {
+ ust_buffers_write(buf, buf_offset,
+ &event_size, sizeof(u32));
+ buf_offset += sizeof(u32);
+ }
+ break;
+ case LTT_RFLAG_ID:
+ ust_buffers_write(buf, buf_offset,
+ &eID, sizeof(u16));
+ buf_offset += sizeof(u16);
+ break;
+ }
+
+ return buf_offset;
+}
#include <kcompat/kref.h>
#include <assert.h>
#include "channels.h"
-#include "buffers.h"
+#include "tracerconst.h"
+#include "tracercore.h"
+#include "header-inline.h"
+#include <usterr.h>
-/* Return the size of the minimum number of pages that can contain x. */
-#define FIX_SIZE(x) ((((x) - 1) & PAGE_MASK) + PAGE_SIZE)
+/***** SHOULD BE REMOVED ***** */
/*
* BUFFER_TRUNC zeroes the subbuffer offset and the subbuffer number parts of
*/
#define UST_CHANNEL_VERSION 8
+/**************************************/
+
+struct commit_counters {
+ local_t cc;
+ local_t cc_sb; /* Incremented _once_ at sb switch */
+};
+
struct ust_buffer {
/* First 32 bytes cache-hot cacheline */
local_t offset; /* Current offset in the buffer */
- local_t *commit_count; /* Commit count per sub-buffer */
+ struct commit_counters *commit_count; /* Commit count per sub-buffer */
atomic_long_t consumed; /*
* Current offset in the buffer
* standard atomic access (shared)
/* the reading end of the pipe */
int data_ready_fd_read;
+ unsigned int finalized;
+//ust// struct timer_list switch_timer; /* timer for periodical switch */
+ unsigned long switch_timer_interval; /* 0 = unset */
+
struct ust_channel *chan;
+
struct kref kref;
void *buf_data;
size_t buf_size;
local_t commit_seq[0] ____cacheline_aligned;
} ____cacheline_aligned;
-extern void _ust_buffers_write(struct ust_buffer *buf, size_t offset,
- const void *src, size_t len, ssize_t cpy);
-
/*
- * Return the address where a given offset is located.
- * Should be used to get the current subbuffer header pointer. Given we know
- * it's never on a page boundary, it's safe to write directly to this address,
- * as long as the write is never bigger than a page size.
+ * A switch is done during tracing or as a final flush after tracing (so it
+ * won't write in the new sub-buffer).
+ * FIXME: make this message clearer
*/
-extern void *ust_buffers_offset_address(struct ust_buffer *buf,
- size_t offset);
+enum force_switch_mode { FORCE_ACTIVE, FORCE_FLUSH };
+
+extern int ltt_reserve_slot_lockless_slow(struct ust_trace *trace,
+ struct ust_channel *ltt_channel, void **transport_data,
+ size_t data_size, size_t *slot_size, long *buf_offset, u64 *tsc,
+ unsigned int *rflags, int largest_align, int cpu);
+
+extern void ltt_force_switch_lockless_slow(struct ust_buffer *buf,
+ enum force_switch_mode mode);
+
-/* FIXME: lttng has a version for systems with inefficient unaligned access */
static __inline__ void ust_buffers_do_copy(void *dest, const void *src, size_t len)
{
union {
} u = { .src = src };
switch (len) {
- case 0: break;
- case 1: *(u8 *)dest = *u.src8;
+ case 0: break;
+ case 1: *(u8 *)dest = *u.src8;
break;
- case 2: *(u16 *)dest = *u.src16;
+ case 2: *(u16 *)dest = *u.src16;
break;
- case 4: *(u32 *)dest = *u.src32;
+ case 4: *(u32 *)dest = *u.src32;
break;
- case 8: *(u64 *)dest = *u.src64;
+ case 8: *(u64 *)dest = *u.src64;
break;
default:
memcpy(dest, src, len);
}
}
-/* FIXME: there is both a static inline and a '_' non static inline version ?? */
+static __inline__ void *ust_buffers_offset_address(struct ust_buffer *buf, size_t offset)
+{
+ return ((char *)buf->buf_data)+offset;
+}
+
+/*
+ * Last TSC comparison functions. Check if the current TSC overflows
+ * LTT_TSC_BITS bits from the last TSC read. Reads and writes last_tsc
+ * atomically.
+ */
+
+/* FIXME: does this test work properly? */
+#if (BITS_PER_LONG == 32)
+static __inline__ void save_last_tsc(struct ust_buffer *ltt_buf,
+ u64 tsc)
+{
+ ltt_buf->last_tsc = (unsigned long)(tsc >> LTT_TSC_BITS);
+}
+
+static __inline__ int last_tsc_overflow(struct ust_buffer *ltt_buf,
+ u64 tsc)
+{
+ unsigned long tsc_shifted = (unsigned long)(tsc >> LTT_TSC_BITS);
+
+ if (unlikely((tsc_shifted - ltt_buf->last_tsc)))
+ return 1;
+ else
+ return 0;
+}
+#else
+static __inline__ void save_last_tsc(struct ust_buffer *ltt_buf,
+ u64 tsc)
+{
+ ltt_buf->last_tsc = (unsigned long)tsc;
+}
+
+static __inline__ int last_tsc_overflow(struct ust_buffer *ltt_buf,
+ u64 tsc)
+{
+ if (unlikely((tsc - ltt_buf->last_tsc) >> LTT_TSC_BITS))
+ return 1;
+ else
+ return 0;
+}
+#endif
+
+static __inline__ void ltt_reserve_push_reader(
+ struct ust_channel *rchan,
+ struct ust_buffer *buf,
+ long offset)
+{
+ long consumed_old, consumed_new;
+
+ do {
+ consumed_old = atomic_long_read(&buf->consumed);
+ /*
+ * If buffer is in overwrite mode, push the reader consumed
+ * count if the write position has reached it and we are not
+ * at the first iteration (don't push the reader farther than
+ * the writer). This operation can be done concurrently by many
+ * writers in the same buffer, the writer being at the farthest
+ * write position sub-buffer index in the buffer being the one
+ * which will win this loop.
+ * If the buffer is not in overwrite mode, pushing the reader
+ * only happens if a sub-buffer is corrupted.
+ */
+ if (unlikely((SUBBUF_TRUNC(offset, buf->chan)
+ - SUBBUF_TRUNC(consumed_old, buf->chan))
+ >= rchan->alloc_size))
+ consumed_new = SUBBUF_ALIGN(consumed_old, buf->chan);
+ else
+ return;
+ } while (unlikely(atomic_long_cmpxchg(&buf->consumed, consumed_old,
+ consumed_new) != consumed_old));
+}
+
+static __inline__ void ltt_vmcore_check_deliver(
+ struct ust_buffer *buf,
+ long commit_count, long idx)
+{
+ local_set(&buf->commit_seq[idx], commit_count);
+}
+
+static __inline__ void ltt_check_deliver(struct ust_channel *chan,
+ struct ust_buffer *buf,
+ long offset, long commit_count, long idx)
+{
+ long old_commit_count = commit_count - chan->subbuf_size;
+
+ /* Check if all commits have been done */
+ if (unlikely((BUFFER_TRUNC(offset, chan)
+ >> chan->n_subbufs_order)
+ - (old_commit_count
+ & chan->commit_count_mask) == 0)) {
+ /*
+ * If we succeeded in updating the cc_sb, we are delivering
+ * the subbuffer. Deals with concurrent updates of the "cc"
+ * value without adding a add_return atomic operation to the
+ * fast path.
+ */
+ if (likely(local_cmpxchg(&buf->commit_count[idx].cc_sb,
+ old_commit_count, commit_count)
+ == old_commit_count)) {
+ int result;
+
+ /*
+ * Set noref flag for this subbuffer.
+ */
+//ust// ltt_set_noref_flag(rchan, buf, idx);
+ ltt_vmcore_check_deliver(buf, commit_count, idx);
+
+ /* wakeup consumer */
+ result = write(buf->data_ready_fd_write, "1", 1);
+ if(result == -1) {
+ PERROR("write (in ltt_relay_buffer_flush)");
+ ERR("this should never happen!");
+ }
+ }
+ }
+}
+
+static __inline__ int ltt_poll_deliver(struct ust_channel *chan, struct ust_buffer *buf)
+{
+ long consumed_old, consumed_idx, commit_count, write_offset;
+
+ consumed_old = atomic_long_read(&buf->consumed);
+ consumed_idx = SUBBUF_INDEX(consumed_old, buf->chan);
+ commit_count = local_read(&buf->commit_count[consumed_idx].cc_sb);
+ /*
+ * No memory barrier here, since we are only interested
+ * in a statistically correct polling result. The next poll will
+ * get the data is we are racing. The mb() that ensures correct
+ * memory order is in get_subbuf.
+ */
+ write_offset = local_read(&buf->offset);
+
+ /*
+ * Check that the subbuffer we are trying to consume has been
+ * already fully committed.
+ */
+
+ if (((commit_count - chan->subbuf_size)
+ & chan->commit_count_mask)
+ - (BUFFER_TRUNC(consumed_old, buf->chan)
+ >> chan->n_subbufs_order)
+ != 0)
+ return 0;
+
+ /*
+ * Check that we are not about to read the same subbuffer in
+ * which the writer head is.
+ */
+ if ((SUBBUF_TRUNC(write_offset, buf->chan)
+ - SUBBUF_TRUNC(consumed_old, buf->chan))
+ == 0)
+ return 0;
+
+ return 1;
+
+}
+
+/*
+ * returns 0 if reserve ok, or 1 if the slow path must be taken.
+ */
+static __inline__ int ltt_relay_try_reserve(
+ struct ust_channel *chan,
+ struct ust_buffer *buf,
+ size_t data_size,
+ u64 *tsc, unsigned int *rflags, int largest_align,
+ long *o_begin, long *o_end, long *o_old,
+ size_t *before_hdr_pad, size_t *size)
+{
+ *o_begin = local_read(&buf->offset);
+ *o_old = *o_begin;
+
+ *tsc = trace_clock_read64();
+
+//ust// #ifdef CONFIG_LTT_VMCORE
+//ust// prefetch(&buf->commit_count[SUBBUF_INDEX(*o_begin, rchan)]);
+//ust// prefetch(&buf->commit_seq[SUBBUF_INDEX(*o_begin, rchan)]);
+//ust// #else
+//ust// prefetchw(&buf->commit_count[SUBBUF_INDEX(*o_begin, rchan)]);
+//ust// #endif
+ if (last_tsc_overflow(buf, *tsc))
+ *rflags = LTT_RFLAG_ID_SIZE_TSC;
+
+ if (unlikely(SUBBUF_OFFSET(*o_begin, buf->chan) == 0))
+ return 1;
+
+ *size = ust_get_header_size(chan,
+ *o_begin, data_size,
+ before_hdr_pad, *rflags);
+ *size += ltt_align(*o_begin + *size, largest_align) + data_size;
+ if (unlikely((SUBBUF_OFFSET(*o_begin, buf->chan) + *size)
+ > buf->chan->subbuf_size))
+ return 1;
+
+ /*
+ * Event fits in the current buffer and we are not on a switch
+ * boundary. It's safe to write.
+ */
+ *o_end = *o_begin + *size;
+
+ if (unlikely((SUBBUF_OFFSET(*o_end, buf->chan)) == 0))
+ /*
+ * The offset_end will fall at the very beginning of the next
+ * subbuffer.
+ */
+ return 1;
+
+ return 0;
+}
+
+static __inline__ int ltt_reserve_slot(struct ust_trace *trace,
+ struct ust_channel *chan, void **transport_data,
+ size_t data_size, size_t *slot_size, long *buf_offset, u64 *tsc,
+ unsigned int *rflags, int largest_align, int cpu)
+{
+ struct ust_buffer *buf = chan->buf[cpu];
+ long o_begin, o_end, o_old;
+ size_t before_hdr_pad;
+
+ /*
+ * Perform retryable operations.
+ */
+ /* FIXME: make this rellay per cpu? */
+ if (unlikely(__get_cpu_var(ltt_nesting) > 4)) {
+ local_inc(&buf->events_lost);
+ return -EPERM;
+ }
+
+ if (unlikely(ltt_relay_try_reserve(chan, buf,
+ data_size, tsc, rflags,
+ largest_align, &o_begin, &o_end, &o_old,
+ &before_hdr_pad, slot_size)))
+ goto slow_path;
+
+ if (unlikely(local_cmpxchg(&buf->offset, o_old, o_end) != o_old))
+ goto slow_path;
+
+ /*
+ * Atomically update last_tsc. This update races against concurrent
+ * atomic updates, but the race will always cause supplementary full TSC
+ * events, never the opposite (missing a full TSC event when it would be
+ * needed).
+ */
+ save_last_tsc(buf, *tsc);
+
+ /*
+ * Push the reader if necessary
+ */
+ ltt_reserve_push_reader(chan, buf, o_end - 1);
+
+ /*
+ * Clear noref flag for this subbuffer.
+ */
+//ust// ltt_clear_noref_flag(chan, buf, SUBBUF_INDEX(o_end - 1, chan));
+
+ *buf_offset = o_begin + before_hdr_pad;
+ return 0;
+slow_path:
+ return ltt_reserve_slot_lockless_slow(trace, chan,
+ transport_data, data_size, slot_size, buf_offset, tsc,
+ rflags, largest_align, cpu);
+}
+
+/*
+ * Force a sub-buffer switch for a per-cpu buffer. This operation is
+ * completely reentrant : can be called while tracing is active with
+ * absolutely no lock held.
+ *
+ * Note, however, that as a local_cmpxchg is used for some atomic
+ * operations, this function must be called from the CPU which owns the buffer
+ * for a ACTIVE flush.
+ */
+static __inline__ void ltt_force_switch(struct ust_buffer *buf,
+ enum force_switch_mode mode)
+{
+ return ltt_force_switch_lockless_slow(buf, mode);
+}
+
+/*
+ * for flight recording. must be called after relay_commit.
+ * This function decrements de subbuffer's lost_size each time the commit count
+ * reaches back the reserve offset (module subbuffer size). It is useful for
+ * crash dump.
+ */
+#ifdef CONFIG_LTT_VMCORE
+static __inline__ void ltt_write_commit_counter(struct rchan_buf *buf,
+ struct ltt_channel_buf_struct *ltt_buf,
+ long idx, long buf_offset, long commit_count, size_t data_size)
+{
+ long offset;
+ long commit_seq_old;
+
+ offset = buf_offset + data_size;
+
+ /*
+ * SUBBUF_OFFSET includes commit_count_mask. We can simply
+ * compare the offsets within the subbuffer without caring about
+ * buffer full/empty mismatch because offset is never zero here
+ * (subbuffer header and event headers have non-zero length).
+ */
+ if (unlikely(SUBBUF_OFFSET(offset - commit_count, buf->chan)))
+ return;
+
+ commit_seq_old = local_read(<t_buf->commit_seq[idx]);
+ while (commit_seq_old < commit_count)
+ commit_seq_old = local_cmpxchg(<t_buf->commit_seq[idx],
+ commit_seq_old, commit_count);
+}
+#else
+static __inline__ void ltt_write_commit_counter(struct ust_buffer *buf,
+ long idx, long buf_offset, long commit_count, size_t data_size)
+{
+}
+#endif
+
+/*
+ * Atomic unordered slot commit. Increments the commit count in the
+ * specified sub-buffer, and delivers it if necessary.
+ *
+ * Parameters:
+ *
+ * @ltt_channel : channel structure
+ * @transport_data: transport-specific data
+ * @buf_offset : offset following the event header.
+ * @data_size : size of the event data.
+ * @slot_size : size of the reserved slot.
+ */
+static __inline__ void ltt_commit_slot(
+ struct ust_channel *chan,
+ struct ust_buffer *buf, long buf_offset,
+ size_t data_size, size_t slot_size)
+{
+ long offset_end = buf_offset;
+ long endidx = SUBBUF_INDEX(offset_end - 1, chan);
+ long commit_count;
+
+#ifdef LTT_NO_IPI_BARRIER
+ smp_wmb();
+#else
+ /*
+ * Must write slot data before incrementing commit count.
+ * This compiler barrier is upgraded into a smp_mb() by the IPI
+ * sent by get_subbuf().
+ */
+ barrier();
+#endif
+ local_add(slot_size, &buf->commit_count[endidx].cc);
+ /*
+ * commit count read can race with concurrent OOO commit count updates.
+ * This is only needed for ltt_check_deliver (for non-polling delivery
+ * only) and for ltt_write_commit_counter. The race can only cause the
+ * counter to be read with the same value more than once, which could
+ * cause :
+ * - Multiple delivery for the same sub-buffer (which is handled
+ * gracefully by the reader code) if the value is for a full
+ * sub-buffer. It's important that we can never miss a sub-buffer
+ * delivery. Re-reading the value after the local_add ensures this.
+ * - Reading a commit_count with a higher value that what was actually
+ * added to it for the ltt_write_commit_counter call (again caused by
+ * a concurrent committer). It does not matter, because this function
+ * is interested in the fact that the commit count reaches back the
+ * reserve offset for a specific sub-buffer, which is completely
+ * independent of the order.
+ */
+ commit_count = local_read(&buf->commit_count[endidx].cc);
+
+ ltt_check_deliver(chan, buf, offset_end - 1, commit_count, endidx);
+ /*
+ * Update lost_size for each commit. It's needed only for extracting
+ * ltt buffers from vmcore, after crash.
+ */
+ ltt_write_commit_counter(buf, endidx, buf_offset, commit_count, data_size);
+}
+
+void _ust_buffers_write(struct ust_buffer *buf, size_t offset,
+ const void *src, size_t len, ssize_t cpy);
+
static __inline__ int ust_buffers_write(struct ust_buffer *buf, size_t offset,
- const void *src, size_t len)
+ const void *src, size_t len)
{
size_t cpy;
size_t buf_offset = BUFFER_OFFSET(offset, buf->chan);
cpy = min_t(size_t, len, buf->buf_size - buf_offset);
ust_buffers_do_copy(buf->buf_data + buf_offset, src, cpy);
-
+
if (unlikely(len != cpy))
_ust_buffers_write(buf, buf_offset, src, len, cpy);
return len;
}
-int ust_buffers_channel_open(struct ust_channel *chan, size_t subbuf_size, size_t n_subbufs);
-extern void ust_buffers_channel_close(struct ust_channel *chan);
-
-extern int ust_buffers_do_get_subbuf(struct ust_buffer *buf, long *pconsumed_old);
-
-extern int ust_buffers_do_put_subbuf(struct ust_buffer *buf, u32 uconsumed_old);
-
-extern void init_ustrelay_transport(void);
-
-/*static*/ /* inline */ notrace void ltt_commit_slot(
- struct ust_channel *channel,
- void **transport_data, long buf_offset,
- size_t data_size, size_t slot_size);
+int ust_buffers_get_subbuf(struct ust_buffer *buf, long *consumed);
+int ust_buffers_put_subbuf(struct ust_buffer *buf, unsigned long uconsumed_old);
#endif /* _UST_BUFFERS_H */
projects / lttng-ust.git / commitdiff
