--- /dev/null
+/* LTTng user-space "fast" library
+ *
+ * This daemon is spawned by each traced thread (to share the mmap).
+ *
+ * Its job is to dump periodically this buffer to disk (when it receives a
+ * SIGUSR1 from its parent).
+ *
+ * It uses the control information in the shared memory area (producer/consumer
+ * count).
+ *
+ * When the parent thread dies (yes, those thing may happen) ;) , this daemon
+ * will flush the last buffer and write it to disk.
+ *
+ * Supplement note for streaming : the daemon is responsible for flushing
+ * periodically the buffer if it is streaming data.
+ *
+ *
+ * Notes :
+ * shm memory is typically limited to 4096 units (system wide limit SHMMNI in
+ * /proc/sys/kernel/shmmni). As it requires computation time upon creation, we
+ * do not use it : we will use a shared mmap() instead which is passed through
+ * the fork().
+ * MAP_SHARED mmap segment. Updated when msync or munmap are called.
+ * MAP_ANONYMOUS.
+ * Memory mapped by mmap() is preserved across fork(2), with the same
+ * attributes.
+ *
+ * Eventually, there will be two mode :
+ * * Slow thread spawn : a fork() is done for each new thread. If the process
+ * dies, the data is not lost.
+ * * Fast thread spawn : a pthread_create() is done by the application for each
+ * new thread.
+ *
+ * We use a timer to check periodically if the parent died. I think it is less
+ * intrusive than a ptrace() on the parent, which would get every signal. The
+ * side effect of this is that we won't be notified if the parent does an
+ * exec(). In this case, we will just sit there until the parent exits.
+ *
+ *
+ * Copyright 2006 Mathieu Desnoyers
+ *
+ */
+
+#define inline inline __attribute__((always_inline))
+
+#define _GNU_SOURCE
+#define LTT_TRACE
+#include <sys/types.h>
+#include <sys/wait.h>
+#include <unistd.h>
+#include <stdlib.h>
+#include <stdio.h>
+#include <signal.h>
+#include <syscall.h>
+#include <features.h>
+#include <pthread.h>
+#include <malloc.h>
+#include <string.h>
+#include <sys/mman.h>
+#include <signal.h>
+#include <sys/stat.h>
+#include <fcntl.h>
+#include <stdlib.h>
+#include <sys/param.h>
+#include <sys/time.h>
+#include <errno.h>
+
+#include <asm/atomic.h>
+#include <asm/timex.h> //for get_cycles()
+
+_syscall0(pid_t,gettid)
+
+#include <ltt/ltt-usertrace-fast.h>
+
+#ifdef LTT_SHOW_DEBUG
+#define dbg_printf(...) dbg_printf(__VA_ARGS__)
+#else
+#define dbg_printf(...)
+#endif //LTT_SHOW_DEBUG
+
+
+enum force_switch_mode { FORCE_ACTIVE, FORCE_FLUSH };
+
+/* Writer (the traced application) */
+
+__thread struct ltt_trace_info *thread_trace_info = NULL;
+
+void ltt_usertrace_fast_buffer_switch(void)
+{
+ struct ltt_trace_info *tmp = thread_trace_info;
+ if(tmp)
+ kill(tmp->daemon_id, SIGUSR1);
+}
+
+/* The cleanup should never be called from a signal handler */
+static void ltt_usertrace_fast_cleanup(void *arg)
+{
+ struct ltt_trace_info *tmp = thread_trace_info;
+ if(tmp) {
+ thread_trace_info = NULL;
+ kill(tmp->daemon_id, SIGUSR2);
+ munmap(tmp, sizeof(*tmp));
+ }
+}
+
+/* Reader (the disk dumper daemon) */
+
+static pid_t traced_pid = 0;
+static pid_t traced_tid = 0;
+static int parent_exited = 0;
+
+/* signal handling */
+static void handler_sigusr1(int signo)
+{
+ dbg_printf("LTT Signal %d received : parent buffer switch.\n", signo);
+}
+
+static void handler_sigusr2(int signo)
+{
+ dbg_printf("LTT Signal %d received : parent exited.\n", signo);
+ parent_exited = 1;
+}
+
+static void handler_sigalarm(int signo)
+{
+ dbg_printf("LTT Signal %d received\n", signo);
+
+ if(getppid() != traced_pid) {
+ /* Parent died */
+ dbg_printf("LTT Parent %lu died, cleaning up\n", traced_pid);
+ traced_pid = 0;
+ }
+ alarm(3);
+}
+
+/* Do a buffer switch. Don't switch if buffer is completely empty */
+static void flush_buffer(struct ltt_buf *ltt_buf, enum force_switch_mode mode)
+{
+ uint64_t tsc;
+ int offset_begin, offset_end, offset_old;
+ int reserve_commit_diff;
+ int consumed_old, consumed_new;
+ int commit_count, reserve_count;
+ int end_switch_old;
+
+ do {
+ offset_old = atomic_read(<t_buf->offset);
+ offset_begin = offset_old;
+ end_switch_old = 0;
+ tsc = ltt_get_timestamp();
+ if(tsc == 0) {
+ /* Error in getting the timestamp : should not happen : it would
+ * mean we are called from an NMI during a write seqlock on xtime. */
+ return;
+ }
+
+ if(SUBBUF_OFFSET(offset_begin, ltt_buf) != 0) {
+ offset_begin = SUBBUF_ALIGN(offset_begin, ltt_buf);
+ end_switch_old = 1;
+ } else {
+ /* we do not have to switch : buffer is empty */
+ return;
+ }
+ if(mode == FORCE_ACTIVE)
+ offset_begin += ltt_subbuf_header_len(ltt_buf);
+ /* Always begin_switch in FORCE_ACTIVE mode */
+
+ /* Test new buffer integrity */
+ reserve_commit_diff =
+ atomic_read(
+ <t_buf->reserve_count[SUBBUF_INDEX(offset_begin, ltt_buf)])
+ - atomic_read(
+ <t_buf->commit_count[SUBBUF_INDEX(offset_begin, ltt_buf)]);
+ if(reserve_commit_diff == 0) {
+ /* Next buffer not corrupted. */
+ if(mode == FORCE_ACTIVE
+ && (offset_begin-atomic_read(<t_buf->consumed))
+ >= ltt_buf->alloc_size) {
+ /* We do not overwrite non consumed buffers and we are full : ignore
+ switch while tracing is active. */
+ return;
+ }
+ } else {
+ /* Next subbuffer corrupted. Force pushing reader even in normal mode */
+ }
+
+ offset_end = offset_begin;
+ } while(atomic_cmpxchg(<t_buf->offset, offset_old, offset_end)
+ != offset_old);
+
+
+ if(mode == FORCE_ACTIVE) {
+ /* Push the reader if necessary */
+ do {
+ consumed_old = atomic_read(<t_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 fartest 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
+ happen if a sub-buffer is corrupted */
+ if((SUBBUF_TRUNC(offset_end, ltt_buf)
+ - SUBBUF_TRUNC(consumed_old, ltt_buf))
+ >= ltt_buf->alloc_size)
+ consumed_new = SUBBUF_ALIGN(consumed_old, ltt_buf);
+ else {
+ consumed_new = consumed_old;
+ break;
+ }
+ } while(atomic_cmpxchg(<t_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 who died between the reserve and the
+ commit. */
+ if(reserve_commit_diff) {
+ /* We have to alter the sub-buffer commit count : a sub-buffer is
+ corrupted */
+ atomic_add(reserve_commit_diff,
+ <t_buf->commit_count[SUBBUF_INDEX(offset_begin, ltt_buf)]);
+ atomic_inc(<t_buf->corrupted_subbuffers);
+ }
+ }
+ }
+
+ /* Always switch */
+
+ if(end_switch_old) {
+ /* 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 themself.
+ 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.
+ Offset old should never be 0. */
+ ltt_buffer_end_callback(ltt_buf, tsc, offset_old,
+ SUBBUF_INDEX((offset_old), ltt_buf));
+ /* Setting this reserve_count will allow the sub-buffer to be delivered by
+ the last committer. */
+ reserve_count = atomic_add_return((SUBBUF_OFFSET((offset_old-1),
+ ltt_buf) + 1),
+ <t_buf->reserve_count[SUBBUF_INDEX((offset_old),
+ ltt_buf)]);
+ if(reserve_count == atomic_read(
+ <t_buf->commit_count[SUBBUF_INDEX((offset_old), ltt_buf)])) {
+ ltt_deliver_callback(ltt_buf, SUBBUF_INDEX((offset_old), ltt_buf), NULL);
+ }
+ }
+
+ if(mode == FORCE_ACTIVE) {
+ /* New sub-buffer */
+ /* 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 */
+ ltt_buffer_begin_callback(ltt_buf, tsc, SUBBUF_INDEX(offset_begin, ltt_buf));
+ commit_count = atomic_add_return(ltt_subbuf_header_len(ltt_buf),
+ <t_buf->commit_count[SUBBUF_INDEX(offset_begin, ltt_buf)]);
+ /* Check if the written buffer has to be delivered */
+ if(commit_count == atomic_read(
+ <t_buf->reserve_count[SUBBUF_INDEX(offset_begin, ltt_buf)])) {
+ ltt_deliver_callback(ltt_buf, SUBBUF_INDEX(offset_begin, ltt_buf), NULL);
+ }
+ }
+
+}
+
+static inline int ltt_buffer_get(struct ltt_buf *ltt_buf,
+ unsigned int *offset)
+{
+ unsigned int consumed_old, consumed_idx;
+ consumed_old = atomic_read(<t_buf->consumed);
+ consumed_idx = SUBBUF_INDEX(consumed_old, ltt_buf);
+
+ if(atomic_read(<t_buf->commit_count[consumed_idx])
+ != atomic_read(<t_buf->reserve_count[consumed_idx])) {
+ return -EAGAIN;
+ }
+ if((SUBBUF_TRUNC(atomic_read(<t_buf->offset), ltt_buf)
+ -SUBBUF_TRUNC(consumed_old, ltt_buf)) == 0) {
+ return -EAGAIN;
+ }
+
+ *offset = consumed_old;
+
+ return 0;
+}
+
+static inline int ltt_buffer_put(struct ltt_buf *ltt_buf,
+ unsigned int offset)
+{
+ unsigned int consumed_old, consumed_new;
+ int ret;
+
+ consumed_old = offset;
+ consumed_new = SUBBUF_ALIGN(consumed_old, ltt_buf);
+ if(atomic_cmpxchg(<t_buf->consumed, consumed_old, consumed_new)
+ != consumed_old) {
+ /* We have been pushed by the writer : the last buffer read _is_
+ * corrupted!
+ * It can also happen if this is a buffer we never got. */
+ return -EIO;
+ } else {
+ ret = sem_post(<t_buf->writer_sem);
+ if(ret < 0) {
+ printf("error in sem_post");
+ }
+ }
+}
+
+static int read_subbuffer(struct ltt_buf *ltt_buf, int fd)
+{
+ unsigned int consumed_old;
+ int err;
+ dbg_printf("LTT read buffer\n");
+
+
+ err = ltt_buffer_get(ltt_buf, &consumed_old);
+ if(err != 0) {
+ if(err != -EAGAIN) dbg_printf("LTT Reserving sub buffer failed\n");
+ goto get_error;
+ }
+
+ err = TEMP_FAILURE_RETRY(write(fd,
+ ltt_buf->start
+ + (consumed_old & ((ltt_buf->alloc_size)-1)),
+ ltt_buf->subbuf_size));
+
+ if(err < 0) {
+ perror("Error in writing to file");
+ goto write_error;
+ }
+#if 0
+ err = fsync(pair->trace);
+ if(err < 0) {
+ ret = errno;
+ perror("Error in writing to file");
+ goto write_error;
+ }
+#endif //0
+write_error:
+ err = ltt_buffer_put(ltt_buf, consumed_old);
+
+ if(err != 0) {
+ if(err == -EIO) {
+ dbg_printf("Reader has been pushed by the writer, last subbuffer corrupted.\n");
+ /* FIXME : we may delete the last written buffer if we wish. */
+ }
+ goto get_error;
+ }
+
+get_error:
+ return err;
+}
+
+/* This function is called by ltt_rw_init which has signals blocked */
+static void ltt_usertrace_fast_daemon(struct ltt_trace_info *shared_trace_info,
+ sigset_t oldset, pid_t l_traced_pid, pthread_t l_traced_tid)
+{
+ sigset_t set;
+ struct sigaction act;
+ int ret;
+ int fd_process;
+ char outfile_name[PATH_MAX];
+ char identifier_name[PATH_MAX];
+
+
+ traced_pid = l_traced_pid;
+ traced_tid = l_traced_tid;
+
+ dbg_printf("LTT ltt_usertrace_fast_daemon : init is %d, pid is %lu, traced_pid is %lu, traced_tid is %lu\n",
+ shared_trace_info->init, getpid(), traced_pid, traced_tid);
+
+ act.sa_handler = handler_sigusr1;
+ act.sa_flags = 0;
+ sigemptyset(&(act.sa_mask));
+ sigaddset(&(act.sa_mask), SIGUSR1);
+ sigaction(SIGUSR1, &act, NULL);
+
+ act.sa_handler = handler_sigusr2;
+ act.sa_flags = 0;
+ sigemptyset(&(act.sa_mask));
+ sigaddset(&(act.sa_mask), SIGUSR2);
+ sigaction(SIGUSR2, &act, NULL);
+
+ act.sa_handler = handler_sigalarm;
+ act.sa_flags = 0;
+ sigemptyset(&(act.sa_mask));
+ sigaddset(&(act.sa_mask), SIGALRM);
+ sigaction(SIGALRM, &act, NULL);
+
+ alarm(3);
+
+ /* Open output files */
+ umask(00000);
+ ret = mkdir(LTT_USERTRACE_ROOT, 0777);
+ if(ret < 0 && errno != EEXIST) {
+ perror("LTT Error in creating output (mkdir)");
+ exit(-1);
+ }
+ ret = chdir(LTT_USERTRACE_ROOT);
+ if(ret < 0) {
+ perror("LTT Error in creating output (chdir)");
+ exit(-1);
+ }
+ snprintf(identifier_name, PATH_MAX-1, "%lu.%lu.%llu",
+ traced_tid, traced_pid, get_cycles());
+ snprintf(outfile_name, PATH_MAX-1, "process-%s", identifier_name);
+#ifndef LTT_NULL_OUTPUT_TEST
+ fd_process = creat(outfile_name, 0644);
+#else
+ /* NULL test */
+ ret = symlink("/dev/null", outfile_name);
+ if(ret < 0) {
+ perror("error in symlink");
+ }
+ fd_process = open(outfile_name, O_WRONLY);
+ if(fd_process < 0) {
+ perror("Error in open");
+ }
+#endif //LTT_NULL_OUTPUT_TEST
+
+ while(1) {
+ ret = sigsuspend(&oldset);
+ if(ret != -1) {
+ perror("LTT Error in sigsuspend\n");
+ }
+
+ if(traced_pid == 0) break; /* parent died */
+ if(parent_exited) break;
+ dbg_printf("LTT Doing a buffer switch read. pid is : %lu\n", getpid());
+
+ do {
+ ret = read_subbuffer(&shared_trace_info->channel.process, fd_process);
+ } while(ret == 0);
+ }
+
+ /* The parent thread is dead and we have finished with the buffer */
+
+ /* Buffer force switch (flush). Using FLUSH instead of ACTIVE because we know
+ * there is no writer. */
+ flush_buffer(&shared_trace_info->channel.process, FORCE_FLUSH);
+ do {
+ ret = read_subbuffer(&shared_trace_info->channel.process, fd_process);
+ } while(ret == 0);
+
+
+ close(fd_process);
+
+ ret = sem_destroy(&shared_trace_info->channel.process.writer_sem);
+ if(ret < 0) {
+ perror("error in sem_destroy");
+ }
+ munmap(shared_trace_info, sizeof(*shared_trace_info));
+
+ exit(0);
+}
+
+
+/* Reader-writer initialization */
+
+static enum ltt_process_role { LTT_ROLE_WRITER, LTT_ROLE_READER }
+ role = LTT_ROLE_WRITER;
+
+
+void ltt_rw_init(void)
+{
+ pid_t pid;
+ struct ltt_trace_info *shared_trace_info;
+ int ret;
+ sigset_t set, oldset;
+ pid_t l_traced_pid = getpid();
+ pid_t l_traced_tid = gettid();
+
+ /* parent : create the shared memory map */
+ shared_trace_info = mmap(0, sizeof(*thread_trace_info),
+ PROT_READ|PROT_WRITE, MAP_SHARED|MAP_ANONYMOUS, 0, 0);
+ shared_trace_info->init=0;
+ shared_trace_info->filter=0;
+ shared_trace_info->daemon_id=0;
+ shared_trace_info->nesting=0;
+ memset(&shared_trace_info->channel.process, 0,
+ sizeof(shared_trace_info->channel.process));
+ //Need NPTL!
+ ret = sem_init(&shared_trace_info->channel.process.writer_sem, 1,
+ LTT_N_SUBBUFS);
+ if(ret < 0) {
+ perror("error in sem_init");
+ }
+ shared_trace_info->channel.process.alloc_size = LTT_BUF_SIZE_PROCESS;
+ shared_trace_info->channel.process.subbuf_size = LTT_SUBBUF_SIZE_PROCESS;
+ shared_trace_info->channel.process.start =
+ shared_trace_info->channel.process_buf;
+ ltt_buffer_begin_callback(&shared_trace_info->channel.process,
+ ltt_get_timestamp(), 0);
+
+ shared_trace_info->init = 1;
+
+ /* Disable signals */
+ ret = sigfillset(&set);
+ if(ret) {
+ dbg_printf("LTT Error in sigfillset\n");
+ }
+
+
+ ret = pthread_sigmask(SIG_BLOCK, &set, &oldset);
+ if(ret) {
+ dbg_printf("LTT Error in pthread_sigmask\n");
+ }
+
+ pid = fork();
+ if(pid > 0) {
+ /* Parent */
+ shared_trace_info->daemon_id = pid;
+ thread_trace_info = shared_trace_info;
+
+ /* Enable signals */
+ ret = pthread_sigmask(SIG_SETMASK, &oldset, NULL);
+ if(ret) {
+ dbg_printf("LTT Error in pthread_sigmask\n");
+ }
+ } else if(pid == 0) {
+ pid_t sid;
+ /* Child */
+ role = LTT_ROLE_READER;
+ sid = setsid();
+ //Not a good idea to renice, unless futex wait eventually implement
+ //priority inheritence.
+ //ret = nice(1);
+ //if(ret < 0) {
+ // perror("Error in nice");
+ //}
+ if(sid < 0) {
+ perror("Error setting sid");
+ }
+ ltt_usertrace_fast_daemon(shared_trace_info, oldset, l_traced_pid,
+ l_traced_tid);
+ /* Should never return */
+ exit(-1);
+ } else if(pid < 0) {
+ /* fork error */
+ perror("LTT Error in forking ltt-usertrace-fast");
+ }
+}
+
+static __thread struct _pthread_cleanup_buffer cleanup_buffer;
+
+void ltt_thread_init(void)
+{
+ _pthread_cleanup_push(&cleanup_buffer, ltt_usertrace_fast_cleanup, NULL);
+ ltt_rw_init();
+}
+
+void __attribute__((constructor)) __ltt_usertrace_fast_init(void)
+{
+ dbg_printf("LTT usertrace-fast init\n");
+
+ ltt_rw_init();
+}
+
+void __attribute__((destructor)) __ltt_usertrace_fast_fini(void)
+{
+ if(role == LTT_ROLE_WRITER) {
+ dbg_printf("LTT usertrace-fast fini\n");
+ ltt_usertrace_fast_cleanup(NULL);
+ }
+}
+
--- /dev/null
+
+/* LTTng user-space "fast" tracing header
+ *
+ * Copyright 2006 Mathieu Desnoyers
+ *
+ */
+
+#ifndef _LTT_USERTRACE_FAST_H
+#define _LTT_USERTRACE_FAST_H
+
+#ifdef LTT_TRACE
+
+#include <errno.h>
+#include <asm/atomic.h>
+#include <pthread.h>
+#include <stdint.h>
+#include <syscall.h>
+#include <asm/timex.h>
+#include <semaphore.h>
+#include <signal.h>
+
+#include <ltt/ltt-facility-id-user_generic.h>
+#include <ltt/ltt-generic.h>
+
+#ifndef LTT_N_SUBBUFS
+#define LTT_N_SUBBUFS 2
+#endif //LTT_N_SUBBUFS
+
+#ifndef LTT_SUBBUF_SIZE_PROCESS
+#define LTT_SUBBUF_SIZE_PROCESS 1048576
+#endif //LTT_BUF_SIZE_CPU
+
+#define LTT_BUF_SIZE_PROCESS (LTT_SUBBUF_SIZE_PROCESS * LTT_N_SUBBUFS)
+
+#ifndef LTT_USERTRACE_ROOT
+#define LTT_USERTRACE_ROOT "/tmp/ltt-usertrace"
+#endif //LTT_USERTRACE_ROOT
+
+
+/* Buffer offset macros */
+
+#define BUFFER_OFFSET(offset, buf) (offset & (buf->alloc_size-1))
+#define SUBBUF_OFFSET(offset, buf) (offset & (buf->subbuf_size-1))
+#define SUBBUF_ALIGN(offset, buf) \
+ (((offset) + buf->subbuf_size) & (~(buf->subbuf_size-1)))
+#define SUBBUF_TRUNC(offset, buf) \
+ ((offset) & (~(buf->subbuf_size-1)))
+#define SUBBUF_INDEX(offset, buf) \
+ (BUFFER_OFFSET(offset,buf)/buf->subbuf_size)
+
+
+#define LTT_TRACER_MAGIC_NUMBER 0x00D6B7ED
+#define LTT_TRACER_VERSION_MAJOR 0
+#define LTT_TRACER_VERSION_MINOR 7
+
+#ifndef atomic_cmpxchg
+#define atomic_cmpxchg(v, old, new) ((int)cmpxchg(&((v)->counter), old, new))
+#endif //atomic_cmpxchg
+
+typedef unsigned int ltt_facility_t;
+
+struct ltt_trace_header {
+ uint32_t magic_number;
+ uint32_t arch_type;
+ uint32_t arch_variant;
+ uint32_t float_word_order; /* Only useful for user space traces */
+ uint8_t arch_size;
+ //uint32_t system_type;
+ uint8_t major_version;
+ uint8_t minor_version;
+ uint8_t flight_recorder;
+ uint8_t has_heartbeat;
+ uint8_t has_alignment; /* Event header alignment */
+ uint32_t freq_scale;
+ uint64_t start_freq;
+ uint64_t start_tsc;
+ uint64_t start_monotonic;
+ uint64_t start_time_sec;
+ uint64_t start_time_usec;
+} __attribute((packed));
+
+
+struct ltt_block_start_header {
+ struct {
+ uint64_t cycle_count;
+ uint64_t freq; /* khz */
+ } begin;
+ struct {
+ uint64_t cycle_count;
+ uint64_t freq; /* khz */
+ } end;
+ uint32_t lost_size; /* Size unused at the end of the buffer */
+ uint32_t buf_size; /* The size of this sub-buffer */
+ struct ltt_trace_header trace;
+} __attribute((packed));
+
+
+
+struct ltt_buf {
+ void *start;
+ atomic_t offset;
+ atomic_t consumed;
+ atomic_t reserve_count[LTT_N_SUBBUFS];
+ atomic_t commit_count[LTT_N_SUBBUFS];
+
+ atomic_t events_lost;
+ atomic_t corrupted_subbuffers;
+ sem_t writer_sem; /* semaphore on which the writer waits */
+ unsigned int alloc_size;
+ unsigned int subbuf_size;
+};
+
+struct ltt_trace_info {
+ int init;
+ int filter;
+ pid_t daemon_id;
+ int nesting;
+ struct {
+ struct ltt_buf process;
+ char process_buf[LTT_BUF_SIZE_PROCESS] __attribute__ ((aligned (8)));
+ } channel;
+};
+
+
+struct ltt_event_header_nohb {
+ uint64_t timestamp;
+ unsigned char facility_id;
+ unsigned char event_id;
+ uint16_t event_size;
+} __attribute((packed));
+
+extern __thread struct ltt_trace_info *thread_trace_info;
+
+void ltt_thread_init(void);
+
+void __attribute__((no_instrument_function))
+ ltt_usertrace_fast_buffer_switch(void);
+
+/* Get the offset of the channel in the ltt_trace_struct */
+#define GET_CHANNEL_INDEX(chan) \
+ (unsigned int)&((struct ltt_trace_info*)NULL)->channel.chan
+
+/* ltt_get_index_from_facility
+ *
+ * Get channel index from facility and event id.
+ *
+ * @fID : facility ID
+ * @eID : event number
+ *
+ * Get the channel index into which events must be written for the given
+ * facility and event number. We get this structure offset as soon as possible
+ * and remember it so we pass through this logic only once per trace call (not
+ * for every trace).
+ */
+static inline unsigned int __attribute__((no_instrument_function))
+ ltt_get_index_from_facility(ltt_facility_t fID,
+ uint8_t eID)
+{
+ return GET_CHANNEL_INDEX(process);
+}
+
+
+static inline struct ltt_buf * __attribute__((no_instrument_function))
+ ltt_get_channel_from_index(
+ struct ltt_trace_info *trace, unsigned int index)
+{
+ return (struct ltt_buf *)((void*)trace+index);
+}
+
+
+/*
+ * ltt_get_header_size
+ *
+ * Calculate alignment offset for arch size void*. This is the
+ * alignment offset of the event header.
+ *
+ * Important note :
+ * The event header must be a size multiple of the void* size. This is necessary
+ * to be able to calculate statically the alignment offset of the variable
+ * length data fields that follows. The total offset calculated here :
+ *
+ * Alignment of header struct on arch size
+ * + sizeof(header struct)
+ * + padding added to end of struct to align on arch size.
+ * */
+static inline unsigned char __attribute__((no_instrument_function))
+ ltt_get_header_size(struct ltt_trace_info *trace,
+ void *address,
+ size_t *before_hdr_pad,
+ size_t *after_hdr_pad,
+ size_t *header_size)
+{
+ unsigned int padding;
+ unsigned int header;
+
+ header = sizeof(struct ltt_event_header_nohb);
+
+ /* Padding before the header. Calculated dynamically */
+ *before_hdr_pad = ltt_align((unsigned long)address, header);
+ padding = *before_hdr_pad;
+
+ /* Padding after header, considering header aligned on ltt_align.
+ * Calculated statically if header size if known. */
+ *after_hdr_pad = ltt_align(header, sizeof(void*));
+ padding += *after_hdr_pad;
+
+ *header_size = header;
+
+ return header+padding;
+}
+
+
+/* ltt_write_event_header
+ *
+ * Writes the event header to the pointer.
+ *
+ * @channel : pointer to the channel structure
+ * @ptr : buffer pointer
+ * @fID : facility ID
+ * @eID : event ID
+ * @event_size : size of the event, excluding the event header.
+ * @offset : offset of the beginning of the header, for alignment.
+ * Calculated by ltt_get_event_header_size.
+ * @tsc : time stamp counter.
+ */
+static inline void __attribute__((no_instrument_function))
+ ltt_write_event_header(
+ struct ltt_trace_info *trace, struct ltt_buf *buf,
+ void *ptr, ltt_facility_t fID, uint32_t eID, size_t event_size,
+ size_t offset, uint64_t tsc)
+{
+ struct ltt_event_header_nohb *nohb;
+
+ event_size = min(event_size, 0xFFFFU);
+ nohb = (struct ltt_event_header_nohb *)(ptr+offset);
+ nohb->timestamp = (uint64_t)tsc;
+ nohb->facility_id = fID;
+ nohb->event_id = eID;
+ nohb->event_size = (uint16_t)event_size;
+}
+
+
+
+static inline uint64_t __attribute__((no_instrument_function))
+ltt_get_timestamp()
+{
+ return get_cycles();
+}
+
+static inline unsigned int __attribute__((no_instrument_function))
+ltt_subbuf_header_len(struct ltt_buf *buf)
+{
+ return sizeof(struct ltt_block_start_header);
+}
+
+
+
+static inline void __attribute__((no_instrument_function))
+ltt_write_trace_header(struct ltt_trace_header *header)
+{
+ header->magic_number = LTT_TRACER_MAGIC_NUMBER;
+ header->major_version = LTT_TRACER_VERSION_MAJOR;
+ header->minor_version = LTT_TRACER_VERSION_MINOR;
+ header->float_word_order = 0; //FIXME
+ header->arch_type = 0; //FIXME LTT_ARCH_TYPE;
+ header->arch_size = sizeof(void*);
+ header->arch_variant = 0; //FIXME LTT_ARCH_VARIANT;
+ header->flight_recorder = 0;
+ header->has_heartbeat = 0;
+
+#ifndef LTT_PACK
+ header->has_alignment = sizeof(void*);
+#else
+ header->has_alignment = 0;
+#endif
+
+ //FIXME
+ header->freq_scale = 0;
+ header->start_freq = 0;
+ header->start_tsc = 0;
+ header->start_monotonic = 0;
+ header->start_time_sec = 0;
+ header->start_time_usec = 0;
+}
+
+
+static inline void __attribute__((no_instrument_function))
+ltt_buffer_begin_callback(struct ltt_buf *buf,
+ uint64_t tsc, unsigned int subbuf_idx)
+{
+ struct ltt_block_start_header *header =
+ (struct ltt_block_start_header*)
+ (buf->start + (subbuf_idx*buf->subbuf_size));
+
+ header->begin.cycle_count = tsc;
+ header->begin.freq = 0; //ltt_frequency();
+
+ header->lost_size = 0xFFFFFFFF; // for debugging...
+
+ header->buf_size = buf->subbuf_size;
+
+ ltt_write_trace_header(&header->trace);
+
+}
+
+
+
+static inline void __attribute__((no_instrument_function))
+ltt_buffer_end_callback(struct ltt_buf *buf,
+ uint64_t tsc, unsigned int offset, unsigned int subbuf_idx)
+{
+ struct ltt_block_start_header *header =
+ (struct ltt_block_start_header*)
+ (buf->start + (subbuf_idx*buf->subbuf_size));
+ /* offset is assumed to never be 0 here : never deliver a completely
+ * empty subbuffer. */
+ /* The lost size is between 0 and subbuf_size-1 */
+ header->lost_size = SUBBUF_OFFSET((buf->subbuf_size - offset),
+ buf);
+ header->end.cycle_count = tsc;
+ header->end.freq = 0; //ltt_frequency();
+}
+
+
+static inline void __attribute__((no_instrument_function))
+ltt_deliver_callback(struct ltt_buf *buf,
+ unsigned subbuf_idx,
+ void *subbuf)
+{
+ ltt_usertrace_fast_buffer_switch();
+}
+
+
+/* ltt_reserve_slot
+ *
+ * Atomic slot reservation in a LTTng buffer. It will take care of
+ * sub-buffer switching.
+ *
+ * Parameters:
+ *
+ * @trace : the trace structure to log to.
+ * @buf : the buffer to reserve space into.
+ * @data_size : size of the variable length data to log.
+ * @slot_size : pointer to total size of the slot (out)
+ * @tsc : pointer to the tsc at the slot reservation (out)
+ * @before_hdr_pad : dynamic padding before the event header.
+ * @after_hdr_pad : dynamic padding after the event header.
+ *
+ * Return : NULL if not enough space, else returns the pointer
+ * to the beginning of the reserved slot. */
+static inline void * __attribute__((no_instrument_function)) ltt_reserve_slot(
+ struct ltt_trace_info *trace,
+ struct ltt_buf *ltt_buf,
+ unsigned int data_size,
+ unsigned int *slot_size,
+ uint64_t *tsc,
+ size_t *before_hdr_pad,
+ size_t *after_hdr_pad,
+ size_t *header_size)
+{
+ int offset_begin, offset_end, offset_old;
+ //int has_switch;
+ int begin_switch, end_switch_current, end_switch_old;
+ int reserve_commit_diff = 0;
+ unsigned int size;
+ int consumed_old, consumed_new;
+ int commit_count, reserve_count;
+ int ret;
+
+ do {
+ offset_old = atomic_read(<t_buf->offset);
+ offset_begin = offset_old;
+ //has_switch = 0;
+ begin_switch = 0;
+ end_switch_current = 0;
+ end_switch_old = 0;
+ *tsc = ltt_get_timestamp();
+ if(*tsc == 0) {
+ /* Error in getting the timestamp, event lost */
+ atomic_inc(<t_buf->events_lost);
+ return NULL;
+ }
+
+ if(SUBBUF_OFFSET(offset_begin, ltt_buf) == 0) {
+ begin_switch = 1; /* For offset_begin */
+ } else {
+ size = ltt_get_header_size(trace, ltt_buf->start + offset_begin,
+ before_hdr_pad, after_hdr_pad, header_size)
+ + data_size;
+
+ if((SUBBUF_OFFSET(offset_begin, ltt_buf)+size)>ltt_buf->subbuf_size) {
+ //has_switch = 1;
+ end_switch_old = 1; /* For offset_old */
+ begin_switch = 1; /* For offset_begin */
+ }
+ }
+
+ if(begin_switch) {
+ if(end_switch_old) {
+ offset_begin = SUBBUF_ALIGN(offset_begin, ltt_buf);
+ }
+ offset_begin = offset_begin + ltt_subbuf_header_len(ltt_buf);
+ /* Test new buffer integrity */
+ reserve_commit_diff =
+ atomic_read(<t_buf->reserve_count[SUBBUF_INDEX(offset_begin,
+ ltt_buf)])
+ - atomic_read(<t_buf->commit_count[SUBBUF_INDEX(offset_begin,
+ ltt_buf)]);
+ if(reserve_commit_diff == 0) {
+ /* Next buffer not corrupted. */
+ //if((SUBBUF_TRUNC(offset_begin, ltt_buf)
+ // - SUBBUF_TRUNC(atomic_read(<t_buf->consumed), ltt_buf))
+ // >= ltt_buf->alloc_size) {
+ /* sem_wait is not signal safe. Disable signals around it. */
+ {
+ sigset_t oldset, set;
+
+ /* Disable signals */
+ ret = sigfillset(&set);
+ if(ret) perror("LTT Error in sigfillset\n");
+
+ ret = pthread_sigmask(SIG_BLOCK, &set, &oldset);
+ if(ret) perror("LTT Error in pthread_sigmask\n");
+
+ sem_wait(<t_buf->writer_sem);
+
+ /* Enable signals */
+ ret = pthread_sigmask(SIG_SETMASK, &oldset, NULL);
+ if(ret) perror("LTT Error in pthread_sigmask\n");
+ }
+
+ /* go on with the write */
+
+ //} 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. */
+ sem_post(<t_buf->writer_sem);
+ }
+ size = ltt_get_header_size(trace, ltt_buf->start + offset_begin,
+ before_hdr_pad, after_hdr_pad, header_size) + data_size;
+ if((SUBBUF_OFFSET(offset_begin,ltt_buf)+size)>ltt_buf->subbuf_size) {
+ /* Event too big for subbuffers, report error, don't complete
+ * the sub-buffer switch. */
+ atomic_inc(<t_buf->events_lost);
+ return NULL;
+ } 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 */
+ }
+ offset_end = offset_begin + size;
+
+ if((SUBBUF_OFFSET(offset_end, ltt_buf)) == 0) {
+ /* The offset_end will fall at the very beginning of the next subbuffer.
+ */
+ end_switch_current = 1; /* For offset_begin */
+ }
+
+ } while(atomic_cmpxchg(<t_buf->offset, offset_old, offset_end)
+ != offset_old);
+
+
+ /* Push the reader if necessary */
+ do {
+ consumed_old = atomic_read(<t_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 fartest 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
+ happen if a sub-buffer is corrupted */
+ if((SUBBUF_TRUNC(offset_end, ltt_buf)
+ - SUBBUF_TRUNC(consumed_old, ltt_buf))
+ >= ltt_buf->alloc_size)
+ consumed_new = SUBBUF_ALIGN(consumed_old, ltt_buf);
+ else {
+ consumed_new = consumed_old;
+ break;
+ }
+ } while(atomic_cmpxchg(<t_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 who died between the reserve and the
+ commit. */
+ if(reserve_commit_diff) {
+ /* We have to alter the sub-buffer commit count : a sub-buffer is
+ corrupted. We do not deliver it. */
+ atomic_add(reserve_commit_diff,
+ <t_buf->commit_count[SUBBUF_INDEX(offset_begin, ltt_buf)]);
+ atomic_inc(<t_buf->corrupted_subbuffers);
+ }
+ }
+
+
+ if(end_switch_old) {
+ /* 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 themself.
+ 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.*/
+ ltt_buffer_end_callback(ltt_buf, *tsc, offset_old,
+ SUBBUF_INDEX((offset_old-1), ltt_buf));
+ /* Setting this reserve_count will allow the sub-buffer to be delivered by
+ the last committer. */
+ reserve_count =
+ atomic_add_return((SUBBUF_OFFSET((offset_old-1), ltt_buf)+1),
+ <t_buf->reserve_count[SUBBUF_INDEX((offset_old-1), ltt_buf)]);
+ if(reserve_count
+ == atomic_read(<t_buf->commit_count[SUBBUF_INDEX((offset_old-1),
+ ltt_buf)])) {
+ ltt_deliver_callback(ltt_buf, SUBBUF_INDEX((offset_old-1), ltt_buf),
+ NULL);
+ }
+ }
+
+ if(begin_switch) {
+ /* New sub-buffer */
+ /* 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 */
+ ltt_buffer_begin_callback(ltt_buf, *tsc, SUBBUF_INDEX(offset_begin, ltt_buf));
+ commit_count = atomic_add_return(ltt_subbuf_header_len(ltt_buf),
+ <t_buf->commit_count[SUBBUF_INDEX(offset_begin, ltt_buf)]);
+ /* Check if the written buffer has to be delivered */
+ if(commit_count
+ == atomic_read(<t_buf->reserve_count[SUBBUF_INDEX(offset_begin,
+ ltt_buf)])) {
+ ltt_deliver_callback(ltt_buf, SUBBUF_INDEX(offset_begin, ltt_buf), NULL);
+ }
+ }
+
+ if(end_switch_current) {
+ /* 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 themself.
+ 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. */
+ ltt_buffer_end_callback(ltt_buf, *tsc, offset_end,
+ SUBBUF_INDEX((offset_end-1), ltt_buf));
+ /* Setting this reserve_count will allow the sub-buffer to be delivered by
+ the last committer. */
+ reserve_count =
+ atomic_add_return((SUBBUF_OFFSET((offset_end-1), ltt_buf)+1),
+ <t_buf->reserve_count[SUBBUF_INDEX((offset_end-1), ltt_buf)]);
+ if(reserve_count
+ == atomic_read(<t_buf->commit_count[SUBBUF_INDEX((offset_end-1),
+ ltt_buf)])) {
+ ltt_deliver_callback(ltt_buf, SUBBUF_INDEX((offset_end-1), ltt_buf), NULL);
+ }
+ }
+
+ *slot_size = size;
+
+ //BUG_ON(*slot_size != (data_size + *before_hdr_pad + *after_hdr_pad + *header_size));
+ //BUG_ON(*slot_size != (offset_end - offset_begin));
+
+ return ltt_buf->start + BUFFER_OFFSET(offset_begin, ltt_buf);
+}
+
+
+/* ltt_commit_slot
+ *
+ * Atomic unordered slot commit. Increments the commit count in the
+ * specified sub-buffer, and delivers it if necessary.
+ *
+ * Parameters:
+ *
+ * @buf : the buffer to commit to.
+ * @reserved : address of the beginnig of the reserved slot.
+ * @slot_size : size of the reserved slot.
+ *
+ */
+static inline void __attribute__((no_instrument_function)) ltt_commit_slot(
+ struct ltt_buf *ltt_buf,
+ void *reserved,
+ unsigned int slot_size)
+{
+ unsigned int offset_begin = reserved - ltt_buf->start;
+ int commit_count;
+
+ commit_count = atomic_add_return(slot_size,
+ <t_buf->commit_count[SUBBUF_INDEX(offset_begin,
+ ltt_buf)]);
+
+ /* Check if all commits have been done */
+ if(commit_count ==
+ atomic_read(<t_buf->reserve_count[SUBBUF_INDEX(offset_begin, ltt_buf)])) {
+ ltt_deliver_callback(ltt_buf, SUBBUF_INDEX(offset_begin, ltt_buf), NULL);
+ }
+}
+
+
+#endif //LTT_TRACE
+
+
+#endif //_LTT_USERTRACE_FAST_H
+++ /dev/null
-/* LTTng user-space "fast" library
- *
- * This daemon is spawned by each traced thread (to share the mmap).
- *
- * Its job is to dump periodically this buffer to disk (when it receives a
- * SIGUSR1 from its parent).
- *
- * It uses the control information in the shared memory area (producer/consumer
- * count).
- *
- * When the parent thread dies (yes, those thing may happen) ;) , this daemon
- * will flush the last buffer and write it to disk.
- *
- * Supplement note for streaming : the daemon is responsible for flushing
- * periodically the buffer if it is streaming data.
- *
- *
- * Notes :
- * shm memory is typically limited to 4096 units (system wide limit SHMMNI in
- * /proc/sys/kernel/shmmni). As it requires computation time upon creation, we
- * do not use it : we will use a shared mmap() instead which is passed through
- * the fork().
- * MAP_SHARED mmap segment. Updated when msync or munmap are called.
- * MAP_ANONYMOUS.
- * Memory mapped by mmap() is preserved across fork(2), with the same
- * attributes.
- *
- * Eventually, there will be two mode :
- * * Slow thread spawn : a fork() is done for each new thread. If the process
- * dies, the data is not lost.
- * * Fast thread spawn : a pthread_create() is done by the application for each
- * new thread.
- *
- * We use a timer to check periodically if the parent died. I think it is less
- * intrusive than a ptrace() on the parent, which would get every signal. The
- * side effect of this is that we won't be notified if the parent does an
- * exec(). In this case, we will just sit there until the parent exits.
- *
- *
- * Copyright 2006 Mathieu Desnoyers
- *
- */
-
-#define inline inline __attribute__((always_inline))
-
-#define _GNU_SOURCE
-#define LTT_TRACE
-#include <sys/types.h>
-#include <sys/wait.h>
-#include <unistd.h>
-#include <stdlib.h>
-#include <stdio.h>
-#include <signal.h>
-#include <syscall.h>
-#include <features.h>
-#include <pthread.h>
-#include <malloc.h>
-#include <string.h>
-#include <sys/mman.h>
-#include <signal.h>
-#include <sys/stat.h>
-#include <fcntl.h>
-#include <stdlib.h>
-#include <sys/param.h>
-#include <sys/time.h>
-#include <errno.h>
-
-#include <asm/atomic.h>
-#include <asm/timex.h> //for get_cycles()
-
-_syscall0(pid_t,gettid)
-
-#include <ltt/ltt-usertrace-fast.h>
-
-#ifdef LTT_SHOW_DEBUG
-#define dbg_printf(...) dbg_printf(__VA_ARGS__)
-#else
-#define dbg_printf(...)
-#endif //LTT_SHOW_DEBUG
-
-
-enum force_switch_mode { FORCE_ACTIVE, FORCE_FLUSH };
-
-/* Writer (the traced application) */
-
-__thread struct ltt_trace_info *thread_trace_info = NULL;
-
-void ltt_usertrace_fast_buffer_switch(void)
-{
- struct ltt_trace_info *tmp = thread_trace_info;
- if(tmp)
- kill(tmp->daemon_id, SIGUSR1);
-}
-
-/* The cleanup should never be called from a signal handler */
-static void ltt_usertrace_fast_cleanup(void *arg)
-{
- struct ltt_trace_info *tmp = thread_trace_info;
- if(tmp) {
- thread_trace_info = NULL;
- kill(tmp->daemon_id, SIGUSR2);
- munmap(tmp, sizeof(*tmp));
- }
-}
-
-/* Reader (the disk dumper daemon) */
-
-static pid_t traced_pid = 0;
-static pid_t traced_tid = 0;
-static int parent_exited = 0;
-
-/* signal handling */
-static void handler_sigusr1(int signo)
-{
- dbg_printf("LTT Signal %d received : parent buffer switch.\n", signo);
-}
-
-static void handler_sigusr2(int signo)
-{
- dbg_printf("LTT Signal %d received : parent exited.\n", signo);
- parent_exited = 1;
-}
-
-static void handler_sigalarm(int signo)
-{
- dbg_printf("LTT Signal %d received\n", signo);
-
- if(getppid() != traced_pid) {
- /* Parent died */
- dbg_printf("LTT Parent %lu died, cleaning up\n", traced_pid);
- traced_pid = 0;
- }
- alarm(3);
-}
-
-/* Do a buffer switch. Don't switch if buffer is completely empty */
-static void flush_buffer(struct ltt_buf *ltt_buf, enum force_switch_mode mode)
-{
- uint64_t tsc;
- int offset_begin, offset_end, offset_old;
- int reserve_commit_diff;
- int consumed_old, consumed_new;
- int commit_count, reserve_count;
- int end_switch_old;
-
- do {
- offset_old = atomic_read(<t_buf->offset);
- offset_begin = offset_old;
- end_switch_old = 0;
- tsc = ltt_get_timestamp();
- if(tsc == 0) {
- /* Error in getting the timestamp : should not happen : it would
- * mean we are called from an NMI during a write seqlock on xtime. */
- return;
- }
-
- if(SUBBUF_OFFSET(offset_begin, ltt_buf) != 0) {
- offset_begin = SUBBUF_ALIGN(offset_begin, ltt_buf);
- end_switch_old = 1;
- } else {
- /* we do not have to switch : buffer is empty */
- return;
- }
- if(mode == FORCE_ACTIVE)
- offset_begin += ltt_subbuf_header_len(ltt_buf);
- /* Always begin_switch in FORCE_ACTIVE mode */
-
- /* Test new buffer integrity */
- reserve_commit_diff =
- atomic_read(
- <t_buf->reserve_count[SUBBUF_INDEX(offset_begin, ltt_buf)])
- - atomic_read(
- <t_buf->commit_count[SUBBUF_INDEX(offset_begin, ltt_buf)]);
- if(reserve_commit_diff == 0) {
- /* Next buffer not corrupted. */
- if(mode == FORCE_ACTIVE
- && (offset_begin-atomic_read(<t_buf->consumed))
- >= ltt_buf->alloc_size) {
- /* We do not overwrite non consumed buffers and we are full : ignore
- switch while tracing is active. */
- return;
- }
- } else {
- /* Next subbuffer corrupted. Force pushing reader even in normal mode */
- }
-
- offset_end = offset_begin;
- } while(atomic_cmpxchg(<t_buf->offset, offset_old, offset_end)
- != offset_old);
-
-
- if(mode == FORCE_ACTIVE) {
- /* Push the reader if necessary */
- do {
- consumed_old = atomic_read(<t_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 fartest 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
- happen if a sub-buffer is corrupted */
- if((SUBBUF_TRUNC(offset_end, ltt_buf)
- - SUBBUF_TRUNC(consumed_old, ltt_buf))
- >= ltt_buf->alloc_size)
- consumed_new = SUBBUF_ALIGN(consumed_old, ltt_buf);
- else {
- consumed_new = consumed_old;
- break;
- }
- } while(atomic_cmpxchg(<t_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 who died between the reserve and the
- commit. */
- if(reserve_commit_diff) {
- /* We have to alter the sub-buffer commit count : a sub-buffer is
- corrupted */
- atomic_add(reserve_commit_diff,
- <t_buf->commit_count[SUBBUF_INDEX(offset_begin, ltt_buf)]);
- atomic_inc(<t_buf->corrupted_subbuffers);
- }
- }
- }
-
- /* Always switch */
-
- if(end_switch_old) {
- /* 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 themself.
- 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.
- Offset old should never be 0. */
- ltt_buffer_end_callback(ltt_buf, tsc, offset_old,
- SUBBUF_INDEX((offset_old), ltt_buf));
- /* Setting this reserve_count will allow the sub-buffer to be delivered by
- the last committer. */
- reserve_count = atomic_add_return((SUBBUF_OFFSET((offset_old-1),
- ltt_buf) + 1),
- <t_buf->reserve_count[SUBBUF_INDEX((offset_old),
- ltt_buf)]);
- if(reserve_count == atomic_read(
- <t_buf->commit_count[SUBBUF_INDEX((offset_old), ltt_buf)])) {
- ltt_deliver_callback(ltt_buf, SUBBUF_INDEX((offset_old), ltt_buf), NULL);
- }
- }
-
- if(mode == FORCE_ACTIVE) {
- /* New sub-buffer */
- /* 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 */
- ltt_buffer_begin_callback(ltt_buf, tsc, SUBBUF_INDEX(offset_begin, ltt_buf));
- commit_count = atomic_add_return(ltt_subbuf_header_len(ltt_buf),
- <t_buf->commit_count[SUBBUF_INDEX(offset_begin, ltt_buf)]);
- /* Check if the written buffer has to be delivered */
- if(commit_count == atomic_read(
- <t_buf->reserve_count[SUBBUF_INDEX(offset_begin, ltt_buf)])) {
- ltt_deliver_callback(ltt_buf, SUBBUF_INDEX(offset_begin, ltt_buf), NULL);
- }
- }
-
-}
-
-static inline int ltt_buffer_get(struct ltt_buf *ltt_buf,
- unsigned int *offset)
-{
- unsigned int consumed_old, consumed_idx;
- consumed_old = atomic_read(<t_buf->consumed);
- consumed_idx = SUBBUF_INDEX(consumed_old, ltt_buf);
-
- if(atomic_read(<t_buf->commit_count[consumed_idx])
- != atomic_read(<t_buf->reserve_count[consumed_idx])) {
- return -EAGAIN;
- }
- if((SUBBUF_TRUNC(atomic_read(<t_buf->offset), ltt_buf)
- -SUBBUF_TRUNC(consumed_old, ltt_buf)) == 0) {
- return -EAGAIN;
- }
-
- *offset = consumed_old;
-
- return 0;
-}
-
-static inline int ltt_buffer_put(struct ltt_buf *ltt_buf,
- unsigned int offset)
-{
- unsigned int consumed_old, consumed_new;
- int ret;
-
- consumed_old = offset;
- consumed_new = SUBBUF_ALIGN(consumed_old, ltt_buf);
- if(atomic_cmpxchg(<t_buf->consumed, consumed_old, consumed_new)
- != consumed_old) {
- /* We have been pushed by the writer : the last buffer read _is_
- * corrupted!
- * It can also happen if this is a buffer we never got. */
- return -EIO;
- } else {
- ret = sem_post(<t_buf->writer_sem);
- if(ret < 0) {
- printf("error in sem_post");
- }
- }
-}
-
-static int read_subbuffer(struct ltt_buf *ltt_buf, int fd)
-{
- unsigned int consumed_old;
- int err;
- dbg_printf("LTT read buffer\n");
-
-
- err = ltt_buffer_get(ltt_buf, &consumed_old);
- if(err != 0) {
- if(err != -EAGAIN) dbg_printf("LTT Reserving sub buffer failed\n");
- goto get_error;
- }
-
- err = TEMP_FAILURE_RETRY(write(fd,
- ltt_buf->start
- + (consumed_old & ((ltt_buf->alloc_size)-1)),
- ltt_buf->subbuf_size));
-
- if(err < 0) {
- perror("Error in writing to file");
- goto write_error;
- }
-#if 0
- err = fsync(pair->trace);
- if(err < 0) {
- ret = errno;
- perror("Error in writing to file");
- goto write_error;
- }
-#endif //0
-write_error:
- err = ltt_buffer_put(ltt_buf, consumed_old);
-
- if(err != 0) {
- if(err == -EIO) {
- dbg_printf("Reader has been pushed by the writer, last subbuffer corrupted.\n");
- /* FIXME : we may delete the last written buffer if we wish. */
- }
- goto get_error;
- }
-
-get_error:
- return err;
-}
-
-/* This function is called by ltt_rw_init which has signals blocked */
-static void ltt_usertrace_fast_daemon(struct ltt_trace_info *shared_trace_info,
- sigset_t oldset, pid_t l_traced_pid, pthread_t l_traced_tid)
-{
- sigset_t set;
- struct sigaction act;
- int ret;
- int fd_process;
- char outfile_name[PATH_MAX];
- char identifier_name[PATH_MAX];
-
-
- traced_pid = l_traced_pid;
- traced_tid = l_traced_tid;
-
- dbg_printf("LTT ltt_usertrace_fast_daemon : init is %d, pid is %lu, traced_pid is %lu, traced_tid is %lu\n",
- shared_trace_info->init, getpid(), traced_pid, traced_tid);
-
- act.sa_handler = handler_sigusr1;
- act.sa_flags = 0;
- sigemptyset(&(act.sa_mask));
- sigaddset(&(act.sa_mask), SIGUSR1);
- sigaction(SIGUSR1, &act, NULL);
-
- act.sa_handler = handler_sigusr2;
- act.sa_flags = 0;
- sigemptyset(&(act.sa_mask));
- sigaddset(&(act.sa_mask), SIGUSR2);
- sigaction(SIGUSR2, &act, NULL);
-
- act.sa_handler = handler_sigalarm;
- act.sa_flags = 0;
- sigemptyset(&(act.sa_mask));
- sigaddset(&(act.sa_mask), SIGALRM);
- sigaction(SIGALRM, &act, NULL);
-
- alarm(3);
-
- /* Open output files */
- umask(00000);
- ret = mkdir(LTT_USERTRACE_ROOT, 0777);
- if(ret < 0 && errno != EEXIST) {
- perror("LTT Error in creating output (mkdir)");
- exit(-1);
- }
- ret = chdir(LTT_USERTRACE_ROOT);
- if(ret < 0) {
- perror("LTT Error in creating output (chdir)");
- exit(-1);
- }
- snprintf(identifier_name, PATH_MAX-1, "%lu.%lu.%llu",
- traced_tid, traced_pid, get_cycles());
- snprintf(outfile_name, PATH_MAX-1, "process-%s", identifier_name);
-#ifndef LTT_NULL_OUTPUT_TEST
- fd_process = creat(outfile_name, 0644);
-#else
- /* NULL test */
- ret = symlink("/dev/null", outfile_name);
- if(ret < 0) {
- perror("error in symlink");
- }
- fd_process = open(outfile_name, O_WRONLY);
- if(fd_process < 0) {
- perror("Error in open");
- }
-#endif //LTT_NULL_OUTPUT_TEST
-
- while(1) {
- ret = sigsuspend(&oldset);
- if(ret != -1) {
- perror("LTT Error in sigsuspend\n");
- }
-
- if(traced_pid == 0) break; /* parent died */
- if(parent_exited) break;
- dbg_printf("LTT Doing a buffer switch read. pid is : %lu\n", getpid());
-
- do {
- ret = read_subbuffer(&shared_trace_info->channel.process, fd_process);
- } while(ret == 0);
- }
-
- /* The parent thread is dead and we have finished with the buffer */
-
- /* Buffer force switch (flush). Using FLUSH instead of ACTIVE because we know
- * there is no writer. */
- flush_buffer(&shared_trace_info->channel.process, FORCE_FLUSH);
- do {
- ret = read_subbuffer(&shared_trace_info->channel.process, fd_process);
- } while(ret == 0);
-
-
- close(fd_process);
-
- ret = sem_destroy(&shared_trace_info->channel.process.writer_sem);
- if(ret < 0) {
- perror("error in sem_destroy");
- }
- munmap(shared_trace_info, sizeof(*shared_trace_info));
-
- exit(0);
-}
-
-
-/* Reader-writer initialization */
-
-static enum ltt_process_role { LTT_ROLE_WRITER, LTT_ROLE_READER }
- role = LTT_ROLE_WRITER;
-
-
-void ltt_rw_init(void)
-{
- pid_t pid;
- struct ltt_trace_info *shared_trace_info;
- int ret;
- sigset_t set, oldset;
- pid_t l_traced_pid = getpid();
- pid_t l_traced_tid = gettid();
-
- /* parent : create the shared memory map */
- shared_trace_info = mmap(0, sizeof(*thread_trace_info),
- PROT_READ|PROT_WRITE, MAP_SHARED|MAP_ANONYMOUS, 0, 0);
- shared_trace_info->init=0;
- shared_trace_info->filter=0;
- shared_trace_info->daemon_id=0;
- shared_trace_info->nesting=0;
- memset(&shared_trace_info->channel.process, 0,
- sizeof(shared_trace_info->channel.process));
- //Need NPTL!
- ret = sem_init(&shared_trace_info->channel.process.writer_sem, 1,
- LTT_N_SUBBUFS);
- if(ret < 0) {
- perror("error in sem_init");
- }
- shared_trace_info->channel.process.alloc_size = LTT_BUF_SIZE_PROCESS;
- shared_trace_info->channel.process.subbuf_size = LTT_SUBBUF_SIZE_PROCESS;
- shared_trace_info->channel.process.start =
- shared_trace_info->channel.process_buf;
- ltt_buffer_begin_callback(&shared_trace_info->channel.process,
- ltt_get_timestamp(), 0);
-
- shared_trace_info->init = 1;
-
- /* Disable signals */
- ret = sigfillset(&set);
- if(ret) {
- dbg_printf("LTT Error in sigfillset\n");
- }
-
-
- ret = pthread_sigmask(SIG_BLOCK, &set, &oldset);
- if(ret) {
- dbg_printf("LTT Error in pthread_sigmask\n");
- }
-
- pid = fork();
- if(pid > 0) {
- /* Parent */
- shared_trace_info->daemon_id = pid;
- thread_trace_info = shared_trace_info;
-
- /* Enable signals */
- ret = pthread_sigmask(SIG_SETMASK, &oldset, NULL);
- if(ret) {
- dbg_printf("LTT Error in pthread_sigmask\n");
- }
- } else if(pid == 0) {
- pid_t sid;
- /* Child */
- role = LTT_ROLE_READER;
- sid = setsid();
- //Not a good idea to renice, unless futex wait eventually implement
- //priority inheritence.
- //ret = nice(1);
- //if(ret < 0) {
- // perror("Error in nice");
- //}
- if(sid < 0) {
- perror("Error setting sid");
- }
- ltt_usertrace_fast_daemon(shared_trace_info, oldset, l_traced_pid,
- l_traced_tid);
- /* Should never return */
- exit(-1);
- } else if(pid < 0) {
- /* fork error */
- perror("LTT Error in forking ltt-usertrace-fast");
- }
-}
-
-static __thread struct _pthread_cleanup_buffer cleanup_buffer;
-
-void ltt_thread_init(void)
-{
- _pthread_cleanup_push(&cleanup_buffer, ltt_usertrace_fast_cleanup, NULL);
- ltt_rw_init();
-}
-
-void __attribute__((constructor)) __ltt_usertrace_fast_init(void)
-{
- dbg_printf("LTT usertrace-fast init\n");
-
- ltt_rw_init();
-}
-
-void __attribute__((destructor)) __ltt_usertrace_fast_fini(void)
-{
- if(role == LTT_ROLE_WRITER) {
- dbg_printf("LTT usertrace-fast fini\n");
- ltt_usertrace_fast_cleanup(NULL);
- }
-}
-
+++ /dev/null
-
-/* LTTng user-space "fast" tracing header
- *
- * Copyright 2006 Mathieu Desnoyers
- *
- */
-
-#ifndef _LTT_USERTRACE_FAST_H
-#define _LTT_USERTRACE_FAST_H
-
-#ifdef LTT_TRACE
-
-#include <errno.h>
-#include <asm/atomic.h>
-#include <pthread.h>
-#include <stdint.h>
-#include <syscall.h>
-#include <asm/timex.h>
-#include <semaphore.h>
-#include <signal.h>
-
-#include <ltt/ltt-facility-id-user_generic.h>
-#include <ltt/ltt-generic.h>
-
-#ifndef LTT_N_SUBBUFS
-#define LTT_N_SUBBUFS 2
-#endif //LTT_N_SUBBUFS
-
-#ifndef LTT_SUBBUF_SIZE_PROCESS
-#define LTT_SUBBUF_SIZE_PROCESS 1048576
-#endif //LTT_BUF_SIZE_CPU
-
-#define LTT_BUF_SIZE_PROCESS (LTT_SUBBUF_SIZE_PROCESS * LTT_N_SUBBUFS)
-
-#ifndef LTT_USERTRACE_ROOT
-#define LTT_USERTRACE_ROOT "/tmp/ltt-usertrace"
-#endif //LTT_USERTRACE_ROOT
-
-
-/* Buffer offset macros */
-
-#define BUFFER_OFFSET(offset, buf) (offset & (buf->alloc_size-1))
-#define SUBBUF_OFFSET(offset, buf) (offset & (buf->subbuf_size-1))
-#define SUBBUF_ALIGN(offset, buf) \
- (((offset) + buf->subbuf_size) & (~(buf->subbuf_size-1)))
-#define SUBBUF_TRUNC(offset, buf) \
- ((offset) & (~(buf->subbuf_size-1)))
-#define SUBBUF_INDEX(offset, buf) \
- (BUFFER_OFFSET(offset,buf)/buf->subbuf_size)
-
-
-#define LTT_TRACER_MAGIC_NUMBER 0x00D6B7ED
-#define LTT_TRACER_VERSION_MAJOR 0
-#define LTT_TRACER_VERSION_MINOR 7
-
-#ifndef atomic_cmpxchg
-#define atomic_cmpxchg(v, old, new) ((int)cmpxchg(&((v)->counter), old, new))
-#endif //atomic_cmpxchg
-
-typedef unsigned int ltt_facility_t;
-
-struct ltt_trace_header {
- uint32_t magic_number;
- uint32_t arch_type;
- uint32_t arch_variant;
- uint32_t float_word_order; /* Only useful for user space traces */
- uint8_t arch_size;
- //uint32_t system_type;
- uint8_t major_version;
- uint8_t minor_version;
- uint8_t flight_recorder;
- uint8_t has_heartbeat;
- uint8_t has_alignment; /* Event header alignment */
- uint32_t freq_scale;
- uint64_t start_freq;
- uint64_t start_tsc;
- uint64_t start_monotonic;
- uint64_t start_time_sec;
- uint64_t start_time_usec;
-} __attribute((packed));
-
-
-struct ltt_block_start_header {
- struct {
- uint64_t cycle_count;
- uint64_t freq; /* khz */
- } begin;
- struct {
- uint64_t cycle_count;
- uint64_t freq; /* khz */
- } end;
- uint32_t lost_size; /* Size unused at the end of the buffer */
- uint32_t buf_size; /* The size of this sub-buffer */
- struct ltt_trace_header trace;
-} __attribute((packed));
-
-
-
-struct ltt_buf {
- void *start;
- atomic_t offset;
- atomic_t consumed;
- atomic_t reserve_count[LTT_N_SUBBUFS];
- atomic_t commit_count[LTT_N_SUBBUFS];
-
- atomic_t events_lost;
- atomic_t corrupted_subbuffers;
- sem_t writer_sem; /* semaphore on which the writer waits */
- unsigned int alloc_size;
- unsigned int subbuf_size;
-};
-
-struct ltt_trace_info {
- int init;
- int filter;
- pid_t daemon_id;
- int nesting;
- struct {
- struct ltt_buf process;
- char process_buf[LTT_BUF_SIZE_PROCESS] __attribute__ ((aligned (8)));
- } channel;
-};
-
-
-struct ltt_event_header_nohb {
- uint64_t timestamp;
- unsigned char facility_id;
- unsigned char event_id;
- uint16_t event_size;
-} __attribute((packed));
-
-extern __thread struct ltt_trace_info *thread_trace_info;
-
-void ltt_thread_init(void);
-
-void __attribute__((no_instrument_function))
- ltt_usertrace_fast_buffer_switch(void);
-
-/* Get the offset of the channel in the ltt_trace_struct */
-#define GET_CHANNEL_INDEX(chan) \
- (unsigned int)&((struct ltt_trace_info*)NULL)->channel.chan
-
-/* ltt_get_index_from_facility
- *
- * Get channel index from facility and event id.
- *
- * @fID : facility ID
- * @eID : event number
- *
- * Get the channel index into which events must be written for the given
- * facility and event number. We get this structure offset as soon as possible
- * and remember it so we pass through this logic only once per trace call (not
- * for every trace).
- */
-static inline unsigned int __attribute__((no_instrument_function))
- ltt_get_index_from_facility(ltt_facility_t fID,
- uint8_t eID)
-{
- return GET_CHANNEL_INDEX(process);
-}
-
-
-static inline struct ltt_buf * __attribute__((no_instrument_function))
- ltt_get_channel_from_index(
- struct ltt_trace_info *trace, unsigned int index)
-{
- return (struct ltt_buf *)((void*)trace+index);
-}
-
-
-/*
- * ltt_get_header_size
- *
- * Calculate alignment offset for arch size void*. This is the
- * alignment offset of the event header.
- *
- * Important note :
- * The event header must be a size multiple of the void* size. This is necessary
- * to be able to calculate statically the alignment offset of the variable
- * length data fields that follows. The total offset calculated here :
- *
- * Alignment of header struct on arch size
- * + sizeof(header struct)
- * + padding added to end of struct to align on arch size.
- * */
-static inline unsigned char __attribute__((no_instrument_function))
- ltt_get_header_size(struct ltt_trace_info *trace,
- void *address,
- size_t *before_hdr_pad,
- size_t *after_hdr_pad,
- size_t *header_size)
-{
- unsigned int padding;
- unsigned int header;
-
- header = sizeof(struct ltt_event_header_nohb);
-
- /* Padding before the header. Calculated dynamically */
- *before_hdr_pad = ltt_align((unsigned long)address, header);
- padding = *before_hdr_pad;
-
- /* Padding after header, considering header aligned on ltt_align.
- * Calculated statically if header size if known. */
- *after_hdr_pad = ltt_align(header, sizeof(void*));
- padding += *after_hdr_pad;
-
- *header_size = header;
-
- return header+padding;
-}
-
-
-/* ltt_write_event_header
- *
- * Writes the event header to the pointer.
- *
- * @channel : pointer to the channel structure
- * @ptr : buffer pointer
- * @fID : facility ID
- * @eID : event ID
- * @event_size : size of the event, excluding the event header.
- * @offset : offset of the beginning of the header, for alignment.
- * Calculated by ltt_get_event_header_size.
- * @tsc : time stamp counter.
- */
-static inline void __attribute__((no_instrument_function))
- ltt_write_event_header(
- struct ltt_trace_info *trace, struct ltt_buf *buf,
- void *ptr, ltt_facility_t fID, uint32_t eID, size_t event_size,
- size_t offset, uint64_t tsc)
-{
- struct ltt_event_header_nohb *nohb;
-
- event_size = min(event_size, 0xFFFFU);
- nohb = (struct ltt_event_header_nohb *)(ptr+offset);
- nohb->timestamp = (uint64_t)tsc;
- nohb->facility_id = fID;
- nohb->event_id = eID;
- nohb->event_size = (uint16_t)event_size;
-}
-
-
-
-static inline uint64_t __attribute__((no_instrument_function))
-ltt_get_timestamp()
-{
- return get_cycles();
-}
-
-static inline unsigned int __attribute__((no_instrument_function))
-ltt_subbuf_header_len(struct ltt_buf *buf)
-{
- return sizeof(struct ltt_block_start_header);
-}
-
-
-
-static inline void __attribute__((no_instrument_function))
-ltt_write_trace_header(struct ltt_trace_header *header)
-{
- header->magic_number = LTT_TRACER_MAGIC_NUMBER;
- header->major_version = LTT_TRACER_VERSION_MAJOR;
- header->minor_version = LTT_TRACER_VERSION_MINOR;
- header->float_word_order = 0; //FIXME
- header->arch_type = 0; //FIXME LTT_ARCH_TYPE;
- header->arch_size = sizeof(void*);
- header->arch_variant = 0; //FIXME LTT_ARCH_VARIANT;
- header->flight_recorder = 0;
- header->has_heartbeat = 0;
-
-#ifndef LTT_PACK
- header->has_alignment = sizeof(void*);
-#else
- header->has_alignment = 0;
-#endif
-
- //FIXME
- header->freq_scale = 0;
- header->start_freq = 0;
- header->start_tsc = 0;
- header->start_monotonic = 0;
- header->start_time_sec = 0;
- header->start_time_usec = 0;
-}
-
-
-static inline void __attribute__((no_instrument_function))
-ltt_buffer_begin_callback(struct ltt_buf *buf,
- uint64_t tsc, unsigned int subbuf_idx)
-{
- struct ltt_block_start_header *header =
- (struct ltt_block_start_header*)
- (buf->start + (subbuf_idx*buf->subbuf_size));
-
- header->begin.cycle_count = tsc;
- header->begin.freq = 0; //ltt_frequency();
-
- header->lost_size = 0xFFFFFFFF; // for debugging...
-
- header->buf_size = buf->subbuf_size;
-
- ltt_write_trace_header(&header->trace);
-
-}
-
-
-
-static inline void __attribute__((no_instrument_function))
-ltt_buffer_end_callback(struct ltt_buf *buf,
- uint64_t tsc, unsigned int offset, unsigned int subbuf_idx)
-{
- struct ltt_block_start_header *header =
- (struct ltt_block_start_header*)
- (buf->start + (subbuf_idx*buf->subbuf_size));
- /* offset is assumed to never be 0 here : never deliver a completely
- * empty subbuffer. */
- /* The lost size is between 0 and subbuf_size-1 */
- header->lost_size = SUBBUF_OFFSET((buf->subbuf_size - offset),
- buf);
- header->end.cycle_count = tsc;
- header->end.freq = 0; //ltt_frequency();
-}
-
-
-static inline void __attribute__((no_instrument_function))
-ltt_deliver_callback(struct ltt_buf *buf,
- unsigned subbuf_idx,
- void *subbuf)
-{
- ltt_usertrace_fast_buffer_switch();
-}
-
-
-/* ltt_reserve_slot
- *
- * Atomic slot reservation in a LTTng buffer. It will take care of
- * sub-buffer switching.
- *
- * Parameters:
- *
- * @trace : the trace structure to log to.
- * @buf : the buffer to reserve space into.
- * @data_size : size of the variable length data to log.
- * @slot_size : pointer to total size of the slot (out)
- * @tsc : pointer to the tsc at the slot reservation (out)
- * @before_hdr_pad : dynamic padding before the event header.
- * @after_hdr_pad : dynamic padding after the event header.
- *
- * Return : NULL if not enough space, else returns the pointer
- * to the beginning of the reserved slot. */
-static inline void * __attribute__((no_instrument_function)) ltt_reserve_slot(
- struct ltt_trace_info *trace,
- struct ltt_buf *ltt_buf,
- unsigned int data_size,
- unsigned int *slot_size,
- uint64_t *tsc,
- size_t *before_hdr_pad,
- size_t *after_hdr_pad,
- size_t *header_size)
-{
- int offset_begin, offset_end, offset_old;
- //int has_switch;
- int begin_switch, end_switch_current, end_switch_old;
- int reserve_commit_diff = 0;
- unsigned int size;
- int consumed_old, consumed_new;
- int commit_count, reserve_count;
- int ret;
-
- do {
- offset_old = atomic_read(<t_buf->offset);
- offset_begin = offset_old;
- //has_switch = 0;
- begin_switch = 0;
- end_switch_current = 0;
- end_switch_old = 0;
- *tsc = ltt_get_timestamp();
- if(*tsc == 0) {
- /* Error in getting the timestamp, event lost */
- atomic_inc(<t_buf->events_lost);
- return NULL;
- }
-
- if(SUBBUF_OFFSET(offset_begin, ltt_buf) == 0) {
- begin_switch = 1; /* For offset_begin */
- } else {
- size = ltt_get_header_size(trace, ltt_buf->start + offset_begin,
- before_hdr_pad, after_hdr_pad, header_size)
- + data_size;
-
- if((SUBBUF_OFFSET(offset_begin, ltt_buf)+size)>ltt_buf->subbuf_size) {
- //has_switch = 1;
- end_switch_old = 1; /* For offset_old */
- begin_switch = 1; /* For offset_begin */
- }
- }
-
- if(begin_switch) {
- if(end_switch_old) {
- offset_begin = SUBBUF_ALIGN(offset_begin, ltt_buf);
- }
- offset_begin = offset_begin + ltt_subbuf_header_len(ltt_buf);
- /* Test new buffer integrity */
- reserve_commit_diff =
- atomic_read(<t_buf->reserve_count[SUBBUF_INDEX(offset_begin,
- ltt_buf)])
- - atomic_read(<t_buf->commit_count[SUBBUF_INDEX(offset_begin,
- ltt_buf)]);
- if(reserve_commit_diff == 0) {
- /* Next buffer not corrupted. */
- //if((SUBBUF_TRUNC(offset_begin, ltt_buf)
- // - SUBBUF_TRUNC(atomic_read(<t_buf->consumed), ltt_buf))
- // >= ltt_buf->alloc_size) {
- /* sem_wait is not signal safe. Disable signals around it. */
- {
- sigset_t oldset, set;
-
- /* Disable signals */
- ret = sigfillset(&set);
- if(ret) perror("LTT Error in sigfillset\n");
-
- ret = pthread_sigmask(SIG_BLOCK, &set, &oldset);
- if(ret) perror("LTT Error in pthread_sigmask\n");
-
- sem_wait(<t_buf->writer_sem);
-
- /* Enable signals */
- ret = pthread_sigmask(SIG_SETMASK, &oldset, NULL);
- if(ret) perror("LTT Error in pthread_sigmask\n");
- }
-
- /* go on with the write */
-
- //} 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. */
- sem_post(<t_buf->writer_sem);
- }
- size = ltt_get_header_size(trace, ltt_buf->start + offset_begin,
- before_hdr_pad, after_hdr_pad, header_size) + data_size;
- if((SUBBUF_OFFSET(offset_begin,ltt_buf)+size)>ltt_buf->subbuf_size) {
- /* Event too big for subbuffers, report error, don't complete
- * the sub-buffer switch. */
- atomic_inc(<t_buf->events_lost);
- return NULL;
- } 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 */
- }
- offset_end = offset_begin + size;
-
- if((SUBBUF_OFFSET(offset_end, ltt_buf)) == 0) {
- /* The offset_end will fall at the very beginning of the next subbuffer.
- */
- end_switch_current = 1; /* For offset_begin */
- }
-
- } while(atomic_cmpxchg(<t_buf->offset, offset_old, offset_end)
- != offset_old);
-
-
- /* Push the reader if necessary */
- do {
- consumed_old = atomic_read(<t_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 fartest 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
- happen if a sub-buffer is corrupted */
- if((SUBBUF_TRUNC(offset_end, ltt_buf)
- - SUBBUF_TRUNC(consumed_old, ltt_buf))
- >= ltt_buf->alloc_size)
- consumed_new = SUBBUF_ALIGN(consumed_old, ltt_buf);
- else {
- consumed_new = consumed_old;
- break;
- }
- } while(atomic_cmpxchg(<t_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 who died between the reserve and the
- commit. */
- if(reserve_commit_diff) {
- /* We have to alter the sub-buffer commit count : a sub-buffer is
- corrupted. We do not deliver it. */
- atomic_add(reserve_commit_diff,
- <t_buf->commit_count[SUBBUF_INDEX(offset_begin, ltt_buf)]);
- atomic_inc(<t_buf->corrupted_subbuffers);
- }
- }
-
-
- if(end_switch_old) {
- /* 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 themself.
- 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.*/
- ltt_buffer_end_callback(ltt_buf, *tsc, offset_old,
- SUBBUF_INDEX((offset_old-1), ltt_buf));
- /* Setting this reserve_count will allow the sub-buffer to be delivered by
- the last committer. */
- reserve_count =
- atomic_add_return((SUBBUF_OFFSET((offset_old-1), ltt_buf)+1),
- <t_buf->reserve_count[SUBBUF_INDEX((offset_old-1), ltt_buf)]);
- if(reserve_count
- == atomic_read(<t_buf->commit_count[SUBBUF_INDEX((offset_old-1),
- ltt_buf)])) {
- ltt_deliver_callback(ltt_buf, SUBBUF_INDEX((offset_old-1), ltt_buf),
- NULL);
- }
- }
-
- if(begin_switch) {
- /* New sub-buffer */
- /* 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 */
- ltt_buffer_begin_callback(ltt_buf, *tsc, SUBBUF_INDEX(offset_begin, ltt_buf));
- commit_count = atomic_add_return(ltt_subbuf_header_len(ltt_buf),
- <t_buf->commit_count[SUBBUF_INDEX(offset_begin, ltt_buf)]);
- /* Check if the written buffer has to be delivered */
- if(commit_count
- == atomic_read(<t_buf->reserve_count[SUBBUF_INDEX(offset_begin,
- ltt_buf)])) {
- ltt_deliver_callback(ltt_buf, SUBBUF_INDEX(offset_begin, ltt_buf), NULL);
- }
- }
-
- if(end_switch_current) {
- /* 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 themself.
- 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. */
- ltt_buffer_end_callback(ltt_buf, *tsc, offset_end,
- SUBBUF_INDEX((offset_end-1), ltt_buf));
- /* Setting this reserve_count will allow the sub-buffer to be delivered by
- the last committer. */
- reserve_count =
- atomic_add_return((SUBBUF_OFFSET((offset_end-1), ltt_buf)+1),
- <t_buf->reserve_count[SUBBUF_INDEX((offset_end-1), ltt_buf)]);
- if(reserve_count
- == atomic_read(<t_buf->commit_count[SUBBUF_INDEX((offset_end-1),
- ltt_buf)])) {
- ltt_deliver_callback(ltt_buf, SUBBUF_INDEX((offset_end-1), ltt_buf), NULL);
- }
- }
-
- *slot_size = size;
-
- //BUG_ON(*slot_size != (data_size + *before_hdr_pad + *after_hdr_pad + *header_size));
- //BUG_ON(*slot_size != (offset_end - offset_begin));
-
- return ltt_buf->start + BUFFER_OFFSET(offset_begin, ltt_buf);
-}
-
-
-/* ltt_commit_slot
- *
- * Atomic unordered slot commit. Increments the commit count in the
- * specified sub-buffer, and delivers it if necessary.
- *
- * Parameters:
- *
- * @buf : the buffer to commit to.
- * @reserved : address of the beginnig of the reserved slot.
- * @slot_size : size of the reserved slot.
- *
- */
-static inline void __attribute__((no_instrument_function)) ltt_commit_slot(
- struct ltt_buf *ltt_buf,
- void *reserved,
- unsigned int slot_size)
-{
- unsigned int offset_begin = reserved - ltt_buf->start;
- int commit_count;
-
- commit_count = atomic_add_return(slot_size,
- <t_buf->commit_count[SUBBUF_INDEX(offset_begin,
- ltt_buf)]);
-
- /* Check if all commits have been done */
- if(commit_count ==
- atomic_read(<t_buf->reserve_count[SUBBUF_INDEX(offset_begin, ltt_buf)])) {
- ltt_deliver_callback(ltt_buf, SUBBUF_INDEX(offset_begin, ltt_buf), NULL);
- }
-}
-
-
-#endif //LTT_TRACE
-
-
-#endif //_LTT_USERTRACE_FAST_H
projects / lttv.git / commitdiff
