1. Patchew
  2. linux
  3. View series

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

Leo Yan posted 1 patch 1 year, 6 months ago
There is a newer version of this series
tools/perf/Documentation/perf-record.txt | 9 +++++----
1 file changed, 5 insertions(+), 4 deletions(-)
[PATCH] perf docs: Refine the description for the buffer size
Posted by Leo Yan 1 year, 6 months ago 
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@arm.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
Re: [PATCH] perf docs: Refine the description for the buffer size
Posted by James Clark 1 year, 5 months ago 

On 10/08/2024 5:15 pm, Leo Yan wrote:
> 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@arm.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

The same text is repeated on a few tools, probably makes sense to update 
them all at the same time.

With that change:

Reviewed-by: James Clark <james.clark@linaro.org>
Re: [PATCH] perf docs: Refine the description for the buffer size
Posted by Leo Yan 1 year, 5 months ago 

On 8/12/24 10:11, James Clark wrote:

[...]

> On 10/08/2024 5:15 pm, Leo Yan wrote:
>> 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@arm.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
> 
> The same text is repeated on a few tools, probably makes sense to update
> them all at the same time.
> 
> With that change:
> 
> Reviewed-by: James Clark <james.clark@linaro.org>

Thanks for review. Sent a new patch with suggestion.

Leo

Patchew 2.1-devel-b67e4c2

© 2016 - 2026 Red Hat, Inc.