Only flush when there are readers active

Signed-off-by: Mathieu Desnoyers <mathieu.desnoyers@efficios.com>

diff --git a/libringbuffer/ring_buffer_frontend.c b/libringbuffer/ring_buffer_frontend.c
index 871d96d1c6e07848348cadbeb872d5a480214add..d0e9466810cc0cb45b7ef51e40a67c08e367cf33 100644 (file)
--- a/libringbuffer/ring_buffer_frontend.c
+++ b/libringbuffer/ring_buffer_frontend.c
@@ -268,29 +268,6 @@ free_chanbuf:
        return ret;
 }
 
-#if 0
-static void switch_buffer_timer(unsigned long data)
-{
-       struct lttng_ust_lib_ring_buffer *buf = (struct lttng_ust_lib_ring_buffer *)data;
-       struct channel *chan = shmp(handle, buf->backend.chan);
-       const struct lttng_ust_lib_ring_buffer_config *config = &chan->backend.config;
-
-       /*
-        * Only flush buffers periodically if readers are active.
-        */
-       if (uatomic_read(&buf->active_readers))
-               lib_ring_buffer_switch_slow(buf, SWITCH_ACTIVE, handle);
-
-       //TODO timers
-       //if (config->alloc == RING_BUFFER_ALLOC_PER_CPU)
-       //      mod_timer_pinned(&buf->switch_timer,
-       //                       jiffies + chan->switch_timer_interval);
-       //else
-       //      mod_timer(&buf->switch_timer,
-       //                jiffies + chan->switch_timer_interval);
-}
-#endif //0
-
 static
 void lib_ring_buffer_channel_switch_timer(int sig, siginfo_t *si, void *uc)
 {
@@ -307,21 +284,25 @@ void lib_ring_buffer_channel_switch_timer(int sig, siginfo_t *si, void *uc)
 
        DBG("Timer for channel %p\n", chan);
 
+       /*
+        * Only flush buffers periodically if readers are active.
+        */
        pthread_mutex_lock(&wakeup_fd_mutex);
        if (config->alloc == RING_BUFFER_ALLOC_PER_CPU) {
                for_each_possible_cpu(cpu) {
                        struct lttng_ust_lib_ring_buffer *buf =
                                shmp(handle, chan->backend.buf[cpu].shmp);
-
-                       lib_ring_buffer_switch_slow(buf, SWITCH_ACTIVE,
-                               chan->handle);
+                       if (uatomic_read(&buf->active_readers))
+                               lib_ring_buffer_switch_slow(buf, SWITCH_ACTIVE,
+                                       chan->handle);
                }
        } else {
                struct lttng_ust_lib_ring_buffer *buf =
                        shmp(handle, chan->backend.buf[0].shmp);
 
-                       lib_ring_buffer_switch_slow(buf, SWITCH_ACTIVE,
-                               chan->handle);
+                       if (uatomic_read(&buf->active_readers))
+                               lib_ring_buffer_switch_slow(buf, SWITCH_ACTIVE,
+                                       chan->handle);
        }
        pthread_mutex_unlock(&wakeup_fd_mutex);
        return;