linux-kernel - [PATCH] perf docs: Refine the description for the buffer size

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Message-Id: <20240810161540.2282535-1-leo.yan@arm.com>
Date: Sat, 10 Aug 2024 17:15:40 +0100
From: Leo Yan <leo.yan@....com>
To: Arnaldo Carvalho de Melo <acme@...nel.org>,
	Peter Zijlstra <peterz@...radead.org>,
	Ingo Molnar <mingo@...hat.com>,
	Namhyung Kim <namhyung@...nel.org>,
	Ian Rogers <irogers@...gle.com>,
	Jiri Olsa <jolsa@...nel.org>,
	Adrian Hunter <adrian.hunter@...el.com>,
	"Liang, Kan" <kan.liang@...ux.intel.com>,
	linux-perf-users@...r.kernel.org,
	linux-kernel@...r.kernel.org,
	james.clark@...aro.org,
	Govindarajan.Mohandoss@....com
Cc: Leo Yan <leo.yan@....com>
Subject: [PATCH] perf docs: Refine the description for the buffer size

Current description for the AUX trace buffer size is misleading. When a
user specifies the option '-m,512M', it represents a size value in bytes
(512MiB) but not 512M pages (512M x 4KiB regard to a page of 4KiB).

Make the document clear that the normal buffer and the AUX tracing
buffer share the same semantics.

Signed-off-by: Leo Yan <leo.yan@....com>
---
 tools/perf/Documentation/perf-record.txt | 9 +++++----
 1 file changed, 5 insertions(+), 4 deletions(-)

diff --git a/tools/perf/Documentation/perf-record.txt b/tools/perf/Documentation/perf-record.txt
index 41e36b4dc765..242223240a08 100644
--- a/tools/perf/Documentation/perf-record.txt
+++ b/tools/perf/Documentation/perf-record.txt
@@ -273,10 +273,11 @@ OPTIONS
 -m::
 --mmap-pages=::
 	Number of mmap data pages (must be a power of two) or size
-	specification with appended unit character - B/K/M/G. The
-	size is rounded up to have nearest pages power of two value.
-	Also, by adding a comma, the number of mmap pages for AUX
-	area tracing can be specified.
+	specification in bytes with appended unit character - B/K/M/G.
+	The size is rounded up to the nearest power-of-two page value.
+	By adding a comma, an additional parameter with the same
+	semantics used for the normal mmap areas can be specified for
+	AUX tracing area.
 
 -g::
 	Enables call-graph (stack chain/backtrace) recording for both
-- 
2.34.1