From: Arnaldo Carvalho de Melo <acme@infradead.org>
To: Lin Ming <ming.m.lin@intel.com>
Cc: Peter Zijlstra <a.p.zijlstra@chello.nl>,
Ingo Molnar <mingo@elte.hu>, Tim Blechmann <tim@klingt.org>,
David Ahern <dsahern@gmail.com>,
linux-kernel <linux-kernel@vger.kernel.org>
Subject: Re: [PATCH] perf: Allow set output buffer for tasks in the same thread group
Date: Mon, 25 Apr 2011 12:28:33 -0300 [thread overview]
Message-ID: <20110425152833.GB32069@ghostprotocols.net> (raw)
In-Reply-To: <1303738838.2578.1.camel@localhost>
Em Mon, Apr 25, 2011 at 09:40:38PM +0800, Lin Ming escreveu:
> On Mon, 2011-04-25 at 01:05 +0800, Peter Zijlstra wrote:
> > On Sun, 2011-04-24 at 22:57 +0800, Lin Ming wrote:
> > > Currently, kernel only allows an event to redirect its output to other
> > > events of the same task.
> > >
> > > This causes PERF_EVENT_IOC_SET_OUTPUT ioctl fails when an event is
> > > trying to redirect its output to other events in the same thread group.
> >
> > Which is exactly what it should do, you should never be allowed to
> > redirect your events to that of another task, since that other task
> > might be running on another CPU.
> >
> > The buffer code strictly assumes no concurrency, therefore its either
> > one task or one CPU.
>
> Well, this is not the right fix, then the perf tool code need to be
> fixed.
Yes, I'm working on it.
- Arnaldo
next prev parent reply other threads:[~2011-04-25 15:28 UTC|newest]
Thread overview: 10+ messages / expand[flat|nested] mbox.gz Atom feed top
2011-04-24 14:57 [PATCH] perf: Allow set output buffer for tasks in the same thread group Lin Ming
2011-04-24 17:05 ` Peter Zijlstra
2011-04-25 13:40 ` Lin Ming
2011-04-25 15:28 ` Arnaldo Carvalho de Melo [this message]
2011-04-26 20:44 ` [PATCH RFC] Fix per-task profiling " Arnaldo Carvalho de Melo
2011-04-26 21:28 ` David Ahern
2011-04-27 2:40 ` Lin Ming
2011-04-27 16:07 ` Arnaldo Carvalho de Melo
2011-05-15 17:49 ` [tip:perf/urgent] perf tools: Honour the cpu list parameter when also monitoring a thread list tip-bot for Arnaldo Carvalho de Melo
2011-05-15 17:49 ` [tip:perf/urgent] perf evlist: Fix per thread mmap setup tip-bot for Arnaldo Carvalho de Melo
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