Messages in this thread Patch in this message |  | | From | Vince Weaver <> | Date | Thu, 16 Apr 2015 14:17:39 -0400 (EDT) | Subject | [patch 07/10] perf_event_open.2: 4.1 add AUX_FLAG_OVERWRITE support |
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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@linux.intel.com>
perf: Support overwrite mode for the AUX area
Signed-off-by: Alexander Shishkin <alexander.shishkin@linux.intel.com> Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org> Cc: Borislav Petkov <bp@alien8.de> Cc: Frederic Weisbecker <fweisbec@gmail.com> Cc: H. Peter Anvin <hpa@zytor.com> Cc: Kaixu Xia <kaixu.xia@linaro.org> Cc: Linus Torvalds <torvalds@linux-foundation.org> Cc: Mike Galbraith <efault@gmx.de> Cc: Paul Mackerras <paulus@samba.org> Cc: Robert Richter <rric@kernel.org> Cc: Stephane Eranian <eranian@google.com> Cc: Thomas Gleixner <tglx@linutronix.de> Cc: acme@infradead.org Cc: adrian.hunter@intel.com Cc: kan.liang@intel.com Cc: markus.t.metzger@intel.com Cc: mathieu.poirier@linaro.org Link: http://lkml.kernel.org/r/1421237903-181015-9-git-send-email-alexander.shishkin@linux.intel.com Signed-off-by: Ingo Molnar <mingo@kernel.org>
Signed-off-by: Vince Weaver <vincent.weaver@maine.edu>
diff --git a/man2/perf_event_open.2 b/man2/perf_event_open.2 --- a/man2/perf_event_open.2 +++ b/man2/perf_event_open.2 @@ -1590,6 +1590,15 @@ .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 @@ -2372,6 +2381,10 @@ .B PERF_AUX_FLAG_TRUNCATED if set then the data returned was truncated to fix 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
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