This manpage patch relates to the addition of the AUX sample flag AUX_FLAG_OVERWRITE as added in the following commit: commit 2023a0d2829e521fe6ad6b9907f3f90bfbf57142 Author: Alexander Shishkin <alexander.shishkin@xxxxxxxxxxxxxxx> perf: Support overwrite mode for the AUX area Signed-off-by: Alexander Shishkin <alexander.shishkin@xxxxxxxxxxxxxxx> Signed-off-by: Peter Zijlstra (Intel) <peterz@xxxxxxxxxxxxx> Cc: Borislav Petkov <bp@xxxxxxxxx> Cc: Frederic Weisbecker <fweisbec@xxxxxxxxx> Cc: H. Peter Anvin <hpa@xxxxxxxxx> Cc: Kaixu Xia <kaixu.xia@xxxxxxxxxx> Cc: Linus Torvalds <torvalds@xxxxxxxxxxxxxxxxxxxx> Cc: Mike Galbraith <efault@xxxxxx> Cc: Paul Mackerras <paulus@xxxxxxxxx> Cc: Robert Richter <rric@xxxxxxxxxx> Cc: Stephane Eranian <eranian@xxxxxxxxxx> Cc: Thomas Gleixner <tglx@xxxxxxxxxxxxx> Cc: acme@xxxxxxxxxxxxx Cc: adrian.hunter@xxxxxxxxx Cc: kan.liang@xxxxxxxxx Cc: markus.t.metzger@xxxxxxxxx Cc: mathieu.poirier@xxxxxxxxxx Link: http://lkml.kernel.org/r/1421237903-181015-9-git-send-email-alexander.shishkin@xxxxxxxxxxxxxxx Signed-off-by: Ingo Molnar <mingo@xxxxxxxxxx> Signed-off-by: Vince Weaver <vincent.weaver@xxxxxxxxx> diff --git a/man2/perf_event_open.2 b/man2/perf_event_open.2 index dfb0b64..238eb62 100644 --- a/man2/perf_event_open.2 +++ b/man2/perf_event_open.2 @@ -1670,6 +1670,15 @@ rlimit as well as the .I perf_event_mlock_kb allowance. +By default the AUX buffer will be truncated if it will not fit +in the available space in the ring buffer. +If the AUX buffer is mapped as a read only buffer, then it will +operate in ring buffer mode where old data will be overwritten +by new. +In overwrite mode it might not be possible to infer where the +new data began, and it is the consumer's job to disable +measurement while reading to avoid possible data races. + The .IR aux_head " and " aux_tail ring buffer pointers have the same behavior and ordering @@ -2476,6 +2485,10 @@ describes the aux update. .B PERF_AUX_FLAG_TRUNCATED if set then the data returned was truncated to fit the available buffer size. +.TP +.B PERF_AUX_FLAG_OVERWRITE +.\" commit 2023a0d2829e521fe6ad6b9907f3f90bfbf57142 +if set then the data returned has overwritten previous data. .RE .RE .RE -- To unsubscribe from this list: send the line "unsubscribe linux-man" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
