From: Andi Kleen <andi@firstfloor.org>
To: Thomas Gleixner <tglx@linutronix.de>
Cc: eranian@gmail.com, linux-kernel@vger.kernel.org,
akpm@linux-foundation.org, mingo@elte.hu, x86@kernel.org,
andi@firstfloor.org, sfr@canb.auug.org.au
Subject: Re: [patch 02/24] perfmon: base code
Date: Thu, 27 Nov 2008 19:41:49 +0100 [thread overview]
Message-ID: <20081127184149.GR6703@one.firstfloor.org> (raw)
In-Reply-To: <alpine.LFD.2.00.0811271858300.3325@localhost.localdomain>
> Well, where is it checked ? Where is checked whether Oprofile runs or not ?
That is done using the perfctr reservation. I saw that somewhere in the
patchkit. The NMI watchdog uses that too.
> > The Oprofile reservation you see is built on top of the cpumask reservation.
> > It tries to allocate in one call and atomically ALL the CPUs as this is the way
> > Oprofile operates. Thus it fails if one perfmon system-wide session or one
> > perfmon per-thread exists.
>
> This only prevents oprofile from starting, but it does neither prevent
> thread sessions nor does it prevent a perfmon per cpu session on a cpu
> which was onlined after oprofile started, simply because it's bit is
> missing in the CPU mask.
The perfctr reservation is global over all CPUs.
-Andi
--
ak@linux.intel.com
next prev parent reply other threads:[~2008-11-27 18:31 UTC|newest]
Thread overview: 14+ messages / expand[flat|nested] mbox.gz Atom feed top
2008-11-26 8:42 [patch 02/24] perfmon: base code eranian
2008-11-26 11:17 ` Andi Kleen
2008-11-27 11:23 ` Thomas Gleixner
2008-11-27 17:24 ` Thomas Gleixner
2008-11-27 17:47 ` stephane eranian
2008-11-27 18:28 ` Thomas Gleixner
2008-11-27 18:41 ` Andi Kleen [this message]
2008-11-27 18:36 ` Thomas Gleixner
2008-11-27 18:54 ` stephane eranian
2008-11-27 18:51 ` stephane eranian
2008-11-27 19:35 ` Thomas Gleixner
2008-11-27 19:49 ` stephane eranian
2008-11-27 20:59 ` Thomas Gleixner
-- strict thread matches above, loose matches on Subject: below --
2008-11-25 21:35 eranian
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