linux-kernel - Re: perf and cgroup event scheduling

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Message-ID: <1301591542.2250.500.camel@laptop>
Date:	Thu, 31 Mar 2011 19:12:22 +0200
From:	Peter Zijlstra <peterz@...radead.org>
To:	Stephane Eranian <eranian@...gle.com>
Cc:	Ingo Molnar <mingo@...e.hu>,
	linux-kernel <linux-kernel@...r.kernel.org>,
	Oleg Nesterov <oleg@...hat.com>
Subject: Re: perf and cgroup event scheduling

On Thu, 2011-03-31 at 10:06 -0700, Stephane Eranian wrote:
> Peter,
> 
> On Thu, Mar 31, 2011 at 6:27 AM, Peter Zijlstra <peterz@...radead.org> wrote:
> > Hi Stephane,
> >
> > while trying to make sense of various other fun event scheduling issues,
> > I noticed that perf_cgroup_switch() isn't always doing the right thing.
> >
> > So we typically want to schedule: CPU-pinned, TASK-pinned, CPU-flexible
> > TASK-flexible, however the current code doesn't respect that.
> >
> Unfortunately, you are right ;-). I think we should try to centralize
> the scheduling
> of per-cpu and per-thread event in a single function that goes through
> the priority
> list. In certain cases, we would sched out and back in per-thread
> events, but that
> would be the only to maintain the priority scheme. I will look into that.

I've done something near to that here:  
  https://lkml.org/lkml/2011/3/31/232

but that patch is very fresh and not tested at all.

> 
> In the meantime, yesterday, I found and fixed one potential kernel crash problem
> related to mixing cgroup + per-thread events. I will be posting the
> patch shortly.

Looking fwd to that, Thanks!

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