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From: Ingo Molnar <mingo@elte.hu>
To: Robert Richter <robert.richter@amd.com>
Cc: "linux-kernel@vger.kernel.org" <linux-kernel@vger.kernel.org>,
	"oprofile-list@lists.sourceforge.net" 
	<oprofile-list@lists.sourceforge.net>,
	Peter Zijlstra <a.p.zijlstra@chello.nl>
Subject: Re: [GIT PULL] oprofile fixes for v2.6.40
Date: Mon, 30 May 2011 12:09:56 +0200	[thread overview]
Message-ID: <20110530100956.GA17821@elte.hu> (raw)
In-Reply-To: <20110530100039.GB20052@erda.amd.com>


* Robert Richter <robert.richter@amd.com> wrote:

> > But i really do not see how this can work. get_eilvt() twiddles 
> > the APIC LVT of this current CPU. Does IBS only activate on a 
> > single CPU? How will this LVT entry be cleared on deinit?
> 
> This is done on the current cpu to get the offset which is then 
> used on all cpus of the system. The actually per-core setup for ibs 
> is in op_amd_setup_ctrs(). Deinit is in op_amd_cpu_shutdown().

The way IBS is set up is not very obvious and atypical of existing 
preempt_*() patters. Might be worth adding a comment to the 
preempt_disable(), to unconfuse unsuspecting readers who are 
wondering about its oddness?

Anyway, i suspected that it was correctly working code so i pulled it 
and pushed it to Linus, it should all be in 3.0-rc1.

Thanks,

	Ingo

  reply	other threads:[~2011-05-30 10:10 UTC|newest]

Thread overview: 8+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2011-05-26 13:39 [GIT PULL] oprofile fixes for v2.6.40 Robert Richter
2011-05-27 12:23 ` Ingo Molnar
2011-05-30 10:00   ` Robert Richter
2011-05-30 10:09     ` Ingo Molnar [this message]
2011-05-30 10:16       ` Robert Richter
2011-05-30 14:41         ` Robert Richter
2011-05-30 14:44           ` Ingo Molnar
2011-05-30 14:43         ` [PATCH] oprofile, x86: Add comments to IBS LVT offset initialization Robert Richter

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