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Date: Thu, 23 Jul 2015 13:13:52 -0400 (EDT) From: Vince Weaver <vincent.weaver@...ne.edu> To: "Michael Kerrisk (man-pages)" <mtk.manpages@...il.com> cc: linux-man@...r.kernel.org, linux-kernel@...r.kernel.org, Peter Zijlstra <a.p.zijlstra@...llo.nl>, Ingo Molnar <mingo@...hat.com>, Arnaldo Carvalho de Melo <acme@...nel.org>, Stephane Eranian <eranian@...gle.com>, Alexander Shishkin <alexander.shishkin@...ux.intel.com>, Borislav Petkov <bp@...en8.de>, Frederic Weisbecker <fweisbec@...il.com>, "H. Peter Anvin" <hpa@...or.com>, Kaixu Xia <kaixu.xia@...aro.org>, Linus Torvalds <torvalds@...ux-foundation.org>, Mike Galbraith <efault@....de>, Robert Richter <rric@...nel.org>, Thomas Gleixner <tglx@...utronix.de>, adrian.hunter@...el.com, kan.liang@...el.com, markus.t.metzger@...el.com, mathieu.poirier@...aro.org, Vince Weaver <vincent.weaver@...ne.edu> Subject: [patch 07/11] perf_event_open.2: 4.1 add AUX_FLAG_OVERWRITE support 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@...ux.intel.com> perf: Support overwrite mode for the AUX area Signed-off-by: Alexander Shishkin <alexander.shishkin@...ux.intel.com> Signed-off-by: Peter Zijlstra (Intel) <peterz@...radead.org> Cc: Borislav Petkov <bp@...en8.de> Cc: Frederic Weisbecker <fweisbec@...il.com> Cc: H. Peter Anvin <hpa@...or.com> Cc: Kaixu Xia <kaixu.xia@...aro.org> Cc: Linus Torvalds <torvalds@...ux-foundation.org> Cc: Mike Galbraith <efault@....de> Cc: Paul Mackerras <paulus@...ba.org> Cc: Robert Richter <rric@...nel.org> Cc: Stephane Eranian <eranian@...gle.com> Cc: Thomas Gleixner <tglx@...utronix.de> Cc: acme@...radead.org Cc: adrian.hunter@...el.com Cc: kan.liang@...el.com Cc: markus.t.metzger@...el.com Cc: mathieu.poirier@...aro.org Link: http://lkml.kernel.org/r/1421237903-181015-9-git-send-email-alexander.shishkin@linux.intel.com Signed-off-by: Ingo Molnar <mingo@...nel.org> Signed-off-by: Vince Weaver <vincent.weaver@...ne.edu> 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-kernel" in the body of a message to majordomo@...r.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
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