linux-kernel - Re: [PATCH 04/29] x86/perfcounters: rework pmc_amd_save_disable_all() and pmc_amd_restore

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Message-ID: <20090429125556.GA31500@elte.hu>
Date:	Wed, 29 Apr 2009 14:55:56 +0200
From:	Ingo Molnar <mingo@...e.hu>
To:	Paul Mackerras <paulus@...ba.org>
Cc:	Peter Zijlstra <a.p.zijlstra@...llo.nl>,
	Robert Richter <robert.richter@....com>,
	LKML <linux-kernel@...r.kernel.org>
Subject: Re: [PATCH 04/29] x86/perfcounters: rework
	pmc_amd_save_disable_all() and pmc_amd_restore_all()



* Paul Mackerras <paulus@...ba.org> wrote:

> Ingo Molnar wrote:
> 
> > Could we remove the disable-all facility altogether and make the 
> > core code NMI-safe? The current approach wont scale on CPUs that 
> > dont have global-disable features.
> > 
> > disable-all was arguably a hack i introduced and which spread 
> > too far. Can you see a conceptual need for it?
> 
> If you're talking about hw_perf_save_disable / hw_perf_restore, 
> please don't get rid of those.  I use them to batch up counter 
> enable/disable operations so I only have to compute the PMU config 
> once for each batch rather than every time an individual counter 
> is enabled or disabled.

ok, sure.

	Ingo
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