From: Cyrill Gorcunov <gorcunov@gmail.com>
To: Steven Rostedt <rostedt@goodmis.org>
Cc: Ingo Molnar <mingo@elte.hu>,
Frederic Weisbecker <fweisbec@gmail.com>,
LKML <linux-kernel@vger.kernel.org>,
Peter Zijlstra <peterz@infradead.org>
Subject: Re: [PATCH -tip] x86,perf: P4 PMU -- protect sensible procedures from preemption
Date: Thu, 6 May 2010 18:48:54 +0400 [thread overview]
Message-ID: <20100506144854.GB5583@lenovo> (raw)
In-Reply-To: <1273153525.22438.39.camel@gandalf.stny.rr.com>
On Thu, May 06, 2010 at 09:45:24AM -0400, Steven Rostedt wrote:
...
> > > We want the one with the least runtime overhead. These are instrumentation
> > > routines, so we want to optimize them as much as possible.
>
>
> Yeah, my point was either disable preemption or keep the checks. In
> other words, if you don't disable preemption, do not use
> raw_smp_procesor_id(), because then we will not catch it if it changes
> in the future.
>
> > ok, Ingo, dont apply this patch then for a while.
>
> Send another patch, I'll test it again ;-)
>
> -- Steve
>
>
Ingo, Steven, it seems we have potential preemtion available
in perf_event.c:validate_group:x86_pmu.schedule_events() which
is reached via syscall from userspace perf_event_open() call,
so get_cpu is still needed. But I'm a bit messed with call
graph at the moment :(
-- Cyrill
next prev parent reply other threads:[~2010-05-06 14:49 UTC|newest]
Thread overview: 16+ messages / expand[flat|nested] mbox.gz Atom feed top
2010-05-05 15:07 [PATCH -tip] x86,perf: P4 PMU -- protect sensible procedures from preemption Cyrill Gorcunov
2010-05-05 16:57 ` Frederic Weisbecker
2010-05-05 17:42 ` Cyrill Gorcunov
2010-05-05 17:58 ` Frederic Weisbecker
2010-05-06 6:44 ` Ingo Molnar
2010-05-06 7:39 ` Cyrill Gorcunov
2010-05-06 7:42 ` Ingo Molnar
2010-05-06 7:45 ` Cyrill Gorcunov
2010-05-06 13:45 ` Steven Rostedt
2010-05-06 14:48 ` Cyrill Gorcunov [this message]
2010-05-06 15:26 ` Cyrill Gorcunov
2010-05-06 18:32 ` Steven Rostedt
2010-05-06 18:36 ` Cyrill Gorcunov
-- strict thread matches above, loose matches on Subject: below --
2010-05-07 15:05 Cyrill Gorcunov
2010-05-08 8:06 ` Ingo Molnar
2010-05-08 8:09 ` Cyrill Gorcunov
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