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perf_event_open.2: Document aux_{head,tail,offset,size} support 

This manpage patch relates to the addition of the AUX mmap region
as added in the following commit:

	commit 45bfb2e50471abbbfd83d40d28c986078b0d24ff
	Author: Peter Zijlstra <peterz@infradead.org>

	perf: Add AUX area to ring buffer for raw data streams

	Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
	Acked-by: Alexander Shishkin <alexander.shishkin@linux.intel.com>
	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/1421237903-181015-3-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>
Signed-off-by: Michael Kerrisk <mtk.manpages@gmail.com>
This commit is contained in:
Vince Weaver 2015-07-23 13:12:18 -04:00 committed by Michael Kerrisk
parent 21d9849abb
commit 4e47c6e594
1 changed files with 32 additions and 0 deletions
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32
man2/perf_event_open.2
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@ -1416,6 +1416,10 @@ struct perf_event_mmap_page {
__u64 data_tail; /* user-space written tail */
__u64 data_offset; /* where the buffer starts */
__u64 data_size; /* data buffer size */
__u64 aux_head;
__u64 aux_tail;
__u64 aux_offset;
__u64 aux_size;
}
.fi
@ -1643,6 +1647,34 @@ where perf sample data begins.
.\" commit e8c6deac69629c0cb97c3d3272f8631ef17f8f0f
Contains the size of the perf sample region within
the mmap buffer.
.TP
.IR aux_head ", " aux_tail ", " aux_offset ", " aux_size " (since Linux 4.1)
.\" commit 45bfb2e50471abbbfd83d40d28c986078b0d24ff
The AUX region allows mmaping a separate sample buffer for high
bandwidth data streams (separate from the main perf sample buffer).
An example of a high bandwidth stream is instruction tracing support,
as is found in newer Intel processors.
To set up an AUX area, first
.I aux_offset
needs to be set with an offset greater than
.IR data_offset + data_size
and
.I aux_size
needs to be set to the desired buffer size.
The desired offset and size must be page aligned, and the size
must be a power of two.
These values are then passed to mmap in order to map the AUX buffer.
Pages in the AUX buffer are included as part of the user mlock
rlimit as well as the
.I perf_event_mlock_kb
allowance.
The
.IR aux_head " and " aux_tail
ring buffer pointers have the same behavior and ordering
rules as the previous described
.IR data_head " and " data_tail .
.PP
The following 2^n ring-buffer pages have the layout described below.