linux-kernel - Re: [PATCH] perf_events: fix remapped count support

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Date:	Tue, 23 Mar 2010 22:39:34 +0100
From:	Stephane Eranian <eranian@...gle.com>
To:	Peter Zijlstra <peterz@...radead.org>
Cc:	linux-kernel@...r.kernel.org, mingo@...e.hu, paulus@...ba.org,
	davem@...emloft.net, fweisbec@...il.com, robert.richter@....com,
	perfmon2-devel@...ts.sf.net, eranian@...il.com
Subject: Re: [PATCH] perf_events: fix remapped count support

On Tue, Mar 23, 2010 at 6:41 PM, Peter Zijlstra <peterz@...radead.org> wrote:
> On Tue, 2010-03-23 at 18:25 +0200, Stephane Eranian wrote:
>>         This patch fixes the remapped counter support such that it now works
>>         on X86 processors.
>
> (could you please not add all this whitespace in front? and make sure
>  it's no wider than 70 chars)
>
I will fix that.

> Also, I wouldn't say it fixes it, it's currently not broken, its plain
> not implemented. So this patch adds support for rdpmc.
>
There you go, then.

>>         For other architectures, e.g., PPC, SPARC, assuming they do offer the ability
>>         to read counts directly from user space, all that is needed is a couple of new
>>         arch specific functions:
>
> Power already supports this, so if you just broke this Paul is going to
> be unhappy.
>
I certainly changed the content of hdr->offset. But I don't see how
PPC could have this working otherwise in the presence of multiplex
and thus when you need the timing information to scale.

I'll wait for Paul's comments, then.
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