linux-kernel - Re: [PATCH] perf: Fix intel shared extra msr allocation

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Date:	Tue, 5 Jun 2012 12:38:31 +0200
From:	Stephane Eranian <eranian@...gle.com>
To:	Peter Zijlstra <a.p.zijlstra@...llo.nl>
Cc:	"Yan, Zheng" <zheng.z.yan@...ux.intel.com>,
	"Yan, Zheng" <zheng.z.yan@...el.com>, linux-kernel@...r.kernel.org
Subject: Re: [PATCH] perf: Fix intel shared extra msr allocation

On Tue, Jun 5, 2012 at 12:27 PM, Peter Zijlstra <a.p.zijlstra@...llo.nl> wrote:
> On Tue, 2012-06-05 at 12:21 +0200, Stephane Eranian wrote:
>> I agree with the first part of the patch in intel_try_alt_er(), we
>> should not touch
>> the actual event struct. But I am still unclear about the reg->alloc part.
>
> reg->alloc is part of the actual event.
>
Ok, I missed that (despite writing some of that code ;-<)

> Thing is, the patch is horridly ugly.. while I agree that changing event
> state isn't good, special casing all that code isn't good either.

Yeah, not pretty.

>
> I was looking at cloning the events for validate_group() as well, but so
> far that's not turning out too pretty either.

How about we add a field or flag to cpuc to tell it's fake, and then in
try_alt_er() and __intel_shared_reg_get_constraints() we avoid touching
live struct (like reg->alloc) if fake==1. I think he was trying to do the same
with the core_id == -1 test.
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