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From: Andi Kleen <andi@firstfloor.org>
To: KOSAKI Motohiro <kosaki.motohiro@jp.fujitsu.com>
Cc: Andi Kleen <andi@firstfloor.org>,
	Robert Richter <robert.richter@amd.com>,
	Ingo Molnar <mingo@elte.hu>, LKML <linux-kernel@vger.kernel.org>
Subject: Re: [2.6.28-rc6] oprofile: "opcontrol --start" output two warnings
Date: Tue, 25 Nov 2008 12:09:35 +0100	[thread overview]
Message-ID: <20081125110935.GF6703@one.firstfloor.org> (raw)
In-Reply-To: <20081125192316.26E5.KOSAKI.MOTOHIRO@jp.fujitsu.com>

> if so, I think get_stagger() is a bit strange.
> it depend on caller cpu. then if PREEMPT=Y, it return radom result.

Even without PREEMPT it is random because there is no guarantee the
init code is executing on CPU 0

> 
> I'm not sure about oprofile design.
> but if you are right, I think p4_fill_in_addresses shoudn't use smp_processor_id().

Correct.

> 
> Am I missing any point?

No you're right. Always returning 0 in get_stagger() should be ok
I think, at least it wouldn't make anything worse.

Or perhaps figure out if the per cpu addresses are really needed,
if yes then this would need much more changes. But I hope 
that would not be needed.

But someone should better test it, the P4 perfmon handling is certainly
hairy and I don't claim to understand all its intricate details.

-Andi

-- 
ak@linux.intel.com

      reply	other threads:[~2008-11-25 10:59 UTC|newest]

Thread overview: 4+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2008-11-25  3:18 KOSAKI Motohiro
2008-11-25 10:09 ` Andi Kleen
2008-11-25 10:29   ` KOSAKI Motohiro
2008-11-25 11:09     ` Andi Kleen [this message]

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