linux-kernel - Re: [RFCv2 0/9] perf: Allow leader sampling on inherited events

lists.openwall.net		lists / announce owl-users owl-dev john-users john-dev passwdqc-users yescrypt popa3d-users / oss-security kernel-hardening musl sabotage tlsify passwords / crypt-dev xvendor / Bugtraq Full-Disclosure linux-kernel linux-netdev linux-ext4 linux-hardening linux-cve-announce PHC
Open Source and information security mailing list archives

Hash Suite: Windows password security audit tool. GUI, reports in PDF.

[<prev] [next>] [<thread-prev] [thread-next>] [day] [month] [year] [list]

Message-ID: <20140825145134.GC24926@krava.brq.redhat.com>
Date:	Mon, 25 Aug 2014 16:51:34 +0200
From:	Jiri Olsa <jolsa@...hat.com>
To:	Jiri Olsa <jolsa@...nel.org>
Cc:	linux-kernel@...r.kernel.org, Andi Kleen <andi@...stfloor.org>,
	Arnaldo Carvalho de Melo <acme@...nel.org>,
	Corey Ashford <cjashfor@...ux.vnet.ibm.com>,
	David Ahern <dsahern@...il.com>,
	Frederic Weisbecker <fweisbec@...il.com>,
	Ingo Molnar <mingo@...nel.org>,
	"Jen-Cheng(Tommy) Huang" <tommy24@...ech.edu>,
	Namhyung Kim <namhyung@...nel.org>,
	Paul Mackerras <paulus@...ba.org>,
	Peter Zijlstra <a.p.zijlstra@...llo.nl>,
	Stephane Eranian <eranian@...gle.com>
Subject: Re: [RFCv2 0/9] perf: Allow leader sampling on inherited events

On Mon, Aug 25, 2014 at 04:45:34PM +0200, Jiri Olsa wrote:
> hi,
> Jen-Cheng(Tommy) Huang reported the leader sampling not working
> on children processes:
>   http://www.mail-archive.com/linux-perf-users@vger.kernel.org/msg01644.html
> 
> The leader sampling (example below) lets the group leader event (cycles)
> do the sampling and reads the rest of the group (cache-misses) via
> PERF_FORMAT_GROUP format.
> 
> Example:
>   $ perf record -e '{cycles,cache-misses}:S' <workload>
>   $ perf report --group
> 
>   The perf report --group allows to see all events group
>   data in single view.
> 
> The reason for leader sampling being switched off for inherited
> events, is that the kernel does no allow PERF_FORMAT_GROUP format
> on inherited events (which is used by leader sampling).
> 
> I switched on the PERF_FORMAT_GROUP format for inherited events
> with few other fixies in patches:
>   perf: Deny optimized switch for events read by PERF_SAMPLE_READ
>   perf: Allow PERF_FORMAT_GROUP format on inherited events
> 
> And I fixed perf tool code to be able to process data from
> children processes.
> 
> Anyway, I might have missed some other reason why this was
> never switched on in kernel, so sending this as RFC.
> 
> v2 changes:
>    - detection of the kernel support
>    - added perf script support for period column
>    - separate kernel change for context_equiv change

and as usuall I forgot.. also reachable in here:
  git://git.kernel.org/pub/scm/linux/kernel/git/jolsa/perf.git
  perf/core_format_group

jirka
--
To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
the body of a message to majordomo@...r.kernel.org
More majordomo info at  http://vger.kernel.org/majordomo-info.html
Please read the FAQ at  http://www.tux.org/lkml/