From: Lin Ming <ming.m.lin@intel.com>
To: Peter Zijlstra <a.p.zijlstra@chello.nl>
Cc: Ingo Molnar <mingo@elte.hu>,
Arnaldo Carvalho de Melo <acme@infradead.org>,
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 21:40:38 +0800 [thread overview]
Message-ID: <1303738838.2578.1.camel@localhost> (raw)
In-Reply-To: <1303664726.20212.1.camel@twins>
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.
next prev parent reply other threads:[~2011-04-25 13:40 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 [this message]
2011-04-25 15:28 ` Arnaldo Carvalho de Melo
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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