From 4e47c6e594313ddfa2fd466b33ea0a89a00f513c Mon Sep 17 00:00:00 2001
From: Vince Weaver <vincent.weaver@maine.edu>
Date: Thu, 23 Jul 2015 13:12:18 -0400
Subject: [PATCH] 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>
---
 man2/perf_event_open.2 | 32 ++++++++++++++++++++++++++++++++
 1 file changed, 32 insertions(+)

diff --git a/man2/perf_event_open.2 b/man2/perf_event_open.2
index d71f6979a..dc776483f 100644
--- a/man2/perf_event_open.2
+++ b/man2/perf_event_open.2
@@ -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.