From: David Ahern <dsahern@gmail.com>
To: Namhyung Kim <namhyung@kernel.org>
Cc: Arnaldo Melo <acme@ghostprotocols.net>,
"linux-kernel@vger.kernel.org" <linux-kernel@vger.kernel.org>,
Ingo Molnar <mingo@kernel.org>,
Frederic Weisbecker <fweisbec@gmail.com>,
Peter Zijlstra <a.p.zijlstra@chello.nl>,
Mike Galbraith <efault@gmx.de>, Jiri Olsa <jolsa@redhat.com>,
Stephane Eranian <eranian@google.com>,
Pekka Enberg <penberg@kernel.org>
Subject: Re: [PATCH 6/8] perf sched: Introduce timehist command
Date: Tue, 03 Dec 2013 21:15:29 -0700 [thread overview]
Message-ID: <529EAC61.5080207@gmail.com> (raw)
In-Reply-To: <5297F4D6.3070408@gmail.com>
On 11/28/13, 6:58 PM, David Ahern wrote:
> On 11/28/13, 5:48 PM, Namhyung Kim wrote:
>> Do we really need to look up the callchain to find out an idle thread?
---8<---
>> It seems every idle/swapper thread for each cpu has a pid of 0.
>
I knew I had this code in there for a reason....
Older kernels (e.g., RHEL6) show init as the idle task for cpus != 0.
So, to be robust across kernel versions the idle check needs to do more
than just looking at the swapper thread as the incoming or outgoing
task. It needs to walk the first few frames of the callstack looking for
a known idle symbol.
David
next prev parent reply other threads:[~2013-12-04 4:15 UTC|newest]
Thread overview: 28+ messages / expand[flat|nested] mbox.gz Atom feed top
2013-11-18 20:32 [PATCH 0/8] perf: sched timehist command David Ahern
2013-11-18 20:32 ` [PATCH 1/8] perf tool: Skip ignored symbols while printing callchain David Ahern
2013-11-30 12:52 ` [tip:perf/core] perf evsel: " tip-bot for David Ahern
2013-11-18 20:32 ` [PATCH 2/8] perf symbols: Move idle syms check from top to generic function David Ahern
2013-11-28 8:36 ` Namhyung Kim
2013-11-30 15:58 ` David Ahern
2013-11-30 12:52 ` [tip:perf/core] " tip-bot for David Ahern
2013-11-18 20:32 ` [PATCH 3/8] perf symbol: Save vmlinux or kallsyms path loaded David Ahern
2013-11-22 18:44 ` Arnaldo Carvalho de Melo
2013-11-22 19:13 ` David Ahern
2013-11-22 19:40 ` Arnaldo Carvalho de Melo
2013-11-22 20:09 ` David Ahern
2013-11-18 20:32 ` [PATCH 4/8] perf thread: Move comm_list check into function David Ahern
2013-11-30 12:52 ` [tip:perf/core] " tip-bot for David Ahern
2013-11-18 20:32 ` [PATCH 5/8] perf tool: export setup_list David Ahern
2013-11-28 8:45 ` Namhyung Kim
2013-11-30 12:52 ` [tip:perf/core] perf tools: Export setup_list tip-bot for David Ahern
2013-11-18 20:32 ` [PATCH 6/8] perf sched: Introduce timehist command David Ahern
2013-11-28 9:50 ` Namhyung Kim
2013-11-28 16:01 ` David Ahern
2013-11-28 15:38 ` Namhyung Kim
2013-11-28 16:01 ` David Ahern
2013-11-29 0:48 ` Namhyung Kim
2013-11-29 1:58 ` David Ahern
2013-12-04 4:15 ` David Ahern [this message]
2013-11-18 20:32 ` [PATCH 7/8] perf sched timehist: Add support for context-switch event David Ahern
2013-11-18 20:32 ` [PATCH 8/8] perf sched : Add documentation for timehist options David Ahern
2013-11-28 15:42 ` Namhyung Kim
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