SoW-2019-0002: Dynamic Snapshot

[deliverable/lttng-modules.git] / lib / ringbuffer / config.h

diff --git a/lib/ringbuffer/config.h b/lib/ringbuffer/config.h
index d48654bf1ceecf3f42bb4361437ef78d1dbe9d01..08cbea6e3404fa9904204be90b88ee3c95d9f2d2 100644 (file)
--- a/lib/ringbuffer/config.h
+++ b/lib/ringbuffer/config.h
@@ -101,7 +101,9 @@ struct lib_ring_buffer_client_cb {
  *
  * RING_BUFFER_WAKEUP_BY_WRITER directly wakes up readers when a subbuffer is
  * ready to read. Lower latencies before the reader is woken up. Mainly suitable
- * for drivers.
+ * for drivers. Going through an "irq_work" allows triggering this type of wakeup
+ * even from NMI context: the wakeup will be slightly delayed until the next
+ * interrupts are handled.
  *
  * RING_BUFFER_WAKEUP_NONE does not perform any wakeup whatsoever. The client
  * has the responsibility to perform wakeups.
@@ -142,9 +144,8 @@ struct lib_ring_buffer_config {
        enum {
                RING_BUFFER_WAKEUP_BY_TIMER,    /* wake up performed by timer */
                RING_BUFFER_WAKEUP_BY_WRITER,   /*
-                                                * writer wakes up reader,
-                                                * not lock-free
-                                                * (takes spinlock).
+                                                * writer wakes up reader through
+                                                * irq_work.
                                                 */
        } wakeup;
        /*