linux-kernel - Re: [GIT PULL 00/37] perf/core improvements and fixes

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Message-ID: <20150527073847.GA30999@gmail.com>
Date:	Wed, 27 May 2015 09:38:47 +0200
From:	Ingo Molnar <mingo@...nel.org>
To:	Arnaldo Carvalho de Melo <acme@...nel.org>,
	Adrian Hunter <adrian.hunter@...el.com>
Cc:	linux-kernel@...r.kernel.org,
	Adrian Hunter <adrian.hunter@...el.com>,
	Borislav Petkov <bp@...e.de>, David Ahern <dsahern@...il.com>,
	Don Zickus <dzickus@...hat.com>,
	Frederic Weisbecker <fweisbec@...il.com>,
	Jiri Olsa <jolsa@...hat.com>, Josef Bacik <jbacik@...com>,
	kernel-team@...com, Luigi Semenzato <semenzato@...omium.org>,
	Martin Liska <mliska@...e.cz>,
	Namhyung Kim <namhyung@...nel.org>,
	"Nam T . Nguyen" <namnguyen@...omium.org>,
	Paul Mackerras <paulus@...ba.org>,
	Peter Zijlstra <a.p.zijlstra@...llo.nl>,
	Simon Que <sque@...omium.org>,
	Stephane Eranian <eranian@...gle.com>,
	Arnaldo Carvalho de Melo <acme@...hat.com>
Subject: Re: [GIT PULL 00/37] perf/core improvements and fixes


* Arnaldo Carvalho de Melo <acme@...nel.org> wrote:

> Hi Ingo,
> 
> 	Test built on Fedora21 x86_64, RHEL (5.11 with NO_AUXTRACE=1
> NO_LIBPERL=1 NO_LIBNUMA=1, 6.6 and 7.1) all x86_64.
> 
> 	Please consider applying,
> 
> - Arnaldo
> 
> The following changes since commit d499c106843afa0703a68c64662bf42a16421aec:
> 
>   Merge tag 'perf-core-for-mingo' of git://git.kernel.org/pub/scm/linux/kernel/git/acme/linux into perf/core (2015-05-20 13:23:55 +0200)
> 
> are available in the git repository at:
> 
>   git://git.kernel.org/pub/scm/linux/kernel/git/acme/linux.git tags/perf-core-for-mingo
> 
> for you to fetch changes up to 264ed8843fe2e4c24422ff61de1e3db609106445:
> 
>   perf tools: Put itrace options into an asciidoc include (2015-05-26 13:21:08 -0300)
> 
> ----------------------------------------------------------------
> perf/core improvements and fixes:
> 
> 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?

The changelogs are minimal, sometimes they only say:

  From 7a84d68975f34c912cb6ec8adb3c1869c15b5c36 Mon Sep 17 00:00:00 2001
  From: Adrian Hunter <adrian.hunter@...el.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.

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.

Thanks,

	Ingo

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