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SubjectRe: [GIT PULL 00/37] perf/core improvements and fixes
On 27/05/15 15:35, Arnaldo Carvalho de Melo wrote:
> Em Wed, May 27, 2015 at 09:38:47AM +0200, Ingo Molnar escreveu:
>> * Arnaldo Carvalho de Melo <acme@kernel.org> wrote:
>>> New features:
>
>>> - Intel PT support, should be complete now and possible to test it with what we
>>> already have in the kernel, go, test it and report problems on lkml, I'm sure
>>> Adrian will chime in if something doesn't work as documented. (Adrian Hunter)
>
>> So how can people follow your request?
>
> First by having access to a machine with these hardware features, which,
> for one, I have no easy access to right now :-\
>
>> The changelogs are minimal, sometimes they only say:
>
> They improved over time, over the many resubmits Adrian made, so some
> progress was made on this front.
>
>> From 7a84d68975f34c912cb6ec8adb3c1869c15b5c36 Mon Sep 17 00:00:00 2001
>> From: Adrian Hunter <adrian.hunter@intel.com>
>> Date: Fri, 22 May 2015 14:54:04 +0300
>> Subject: [PATCH] perf tools: Add Intel PT support
>
>> Add support for Intel Processor Trace.
>
>> there's almost zero comments added by these commits.
>
> I shouldn't have let some pass, granted.
>
>> This commit:
>>
>> 928541b6f51f perf tools: Take Intel PT into use
>>
>> adds 'some documentation' under ./Documentation/intel-pt.txt, but that text
>> doesn't actually give any high level description, it doesn't give _any_ way for a
>> user to discover Intel PT support on his own - unless he already knows it, which
>> is kind of circular.
>
>> It doesn't describe which CPUs support Intel PT, what it is, how are people
>> supposed to use it, what the high level capabilities and limitations are, etc.
>> etc.
>
>> So this stuff is user and developer hostile at the moment. We can push this
>> towards Linus only if this becomes _much_ more user and developer friendly. Near
>> zero documentation and near zero comments in the code don't cut it really.
>
> Adrian, can you try to address this further, please?
>
> Something like a handholding session, so that we don't have to dig thru
> all the csets or patch series cover letters, telling:
>
> 1. What hardware one has to have to be able to test it
>
> 2. First command to use
>
> 3. What will be generated, how much space (a lot?) it will use on the
> perf.data file, etc.
>
> 5. What commands have to be used on this perf.data file and what to
> expect from it.
>
> I.e. a HOWTO that starts with a as short as possible description on how
> to use it for the very first time, for people never exposed to Intel PT
> but that can benefit from using it.

I sent the patches again a week ago, but perhaps no one noticed. They are here:

http://marc.info/?l=linux-kernel&m=143290658028132

Comments welcome :-)



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