linux-kernel - Re: [PATCH v2 0/7] perf trace pagefaults

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Message-ID: <20140620132105.GE31524@kernel.org>
Date:	Fri, 20 Jun 2014 10:21:05 -0300
From:	Arnaldo Carvalho de Melo <acme@...nel.org>
To:	Stanislav Fomichev <stfomichev@...dex-team.ru>
Cc:	a.p.zijlstra@...llo.nl, paulus@...ba.org, mingo@...hat.com,
	dsahern@...il.com, jolsa@...hat.com,
	xiaoguangrong@...ux.vnet.ibm.com, yangds.fnst@...fujitsu.com,
	adrian.hunter@...el.com, namhyung@...nel.org,
	linux-kernel@...r.kernel.org
Subject: Re: [PATCH v2 0/7] perf trace pagefaults

Em Fri, Jun 20, 2014 at 02:49:42PM +0400, Stanislav Fomichev escreveu:
> This patch series adds support for pagefaults tracing to 'perf trace' command.
> It seems this feature was planned by Namhyung Kim (http://events.linuxfoundation.org/images/stories/pdf/klf2012_n_kim.pdf page 17/28)
> but I couldn't find any prior patches/discussion and started from scratch.

Just to clarify here, those slides came from slides I made and in turn
the whole idea about pagefaults tracing I got from the trace prototype
that Thomas Gleixner implemented in his 'trace'  utility, described
here:

  Announcing a new utility: 'trace'
  http://lwn.net/Articles/415728/

The comments section has lots of interesting ideas, some you may find
interesting to implement :-)

There is a branch in my tree with the branch tglx did his work on:

https://git.kernel.org/cgit/linux/kernel/git/acme/linux.git/log/?h=tmp.perf/trace2

There you can take a look and compare what you're doing to what he did.

Now I'll go thru your current patches and will cherry pick whatever I
think its OK already, and will try and provide comments for whatever I
think needs more work.

- Arnaldo
 
> First three patches add the feature and options to enable faults and disable
> syscalls.
> Two last patches add events caching (like it's done in the perf kvm), so that
> we don't get fault events prior to mmap/comm events (makes sense only
> for live mode).
> 
> This is just a proof-of-concept, and I'd like to get some comments about
> where and what I got wrong and what additional useful information I can
> expose in the trace.
> 
> v2:
>   - added more info to the changelogs
>   - reworked options (-f -> -F, --pgfaults -> --pf=[all|min|maj])
>   - separated tracepoint_handler changes into additional patch
>   - separated record/replay into additional patch
>   - other fixes pointed out by Arnaldo Carvalho de Melo
> 
> Stanislav Fomichev (7):
>   perf trace: add perf_event parameter to tracepoint_handler
>   perf trace: add support for pagefault tracing
>   perf trace: add pagefaults record and replay support
>   perf trace: add pagefault statistics
>   perf trace: add possibility to switch off syscall events
>   perf kvm: move perf_kvm__mmap_read into session utils
>   perf trace: add events cache
> 
>  tools/perf/Documentation/perf-trace.txt |  19 ++
>  tools/perf/builtin-kvm.c                |  88 +-------
>  tools/perf/builtin-trace.c              | 350 ++++++++++++++++++++++----------
>  tools/perf/util/session.c               |  85 ++++++++
>  tools/perf/util/session.h               |   5 +
>  5 files changed, 357 insertions(+), 190 deletions(-)
> 
> -- 
> 1.8.3.2
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