linux-kernel - Re: [RFC][PATCH 5/8] perf: Reduce perf

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Message-ID: <20100616165244.GB6751@lenovo>
Date:	Wed, 16 Jun 2010 20:52:44 +0400
From:	Cyrill Gorcunov <gorcunov@...il.com>
To:	Peter Zijlstra <a.p.zijlstra@...llo.nl>
Cc:	paulus <paulus@...ba.org>,
	stephane eranian <eranian@...glemail.com>,
	Robert Richter <robert.richter@....com>,
	Will Deacon <will.deacon@....com>,
	Paul Mundt <lethal@...ux-sh.org>,
	Frederic Weisbecker <fweisbec@...il.com>,
	Lin Ming <ming.m.lin@...el.com>,
	Yanmin <yanmin_zhang@...ux.intel.com>,
	Deng-Cheng Zhu <dengcheng.zhu@...il.com>,
	David Miller <davem@...emloft.net>,
	linux-kernel@...r.kernel.org
Subject: Re: [RFC][PATCH 5/8] perf: Reduce perf_disable() usage

On Wed, Jun 16, 2010 at 06:00:32PM +0200, Peter Zijlstra wrote:
> Since the current perf_disable() usage is only an optimization, remove
> it for now. This eases the removal of the weak hw_perf_enable
> interface.
> 
> [ Some comments talk about NMI races, but I cannot find any such
>   things. ]
> 

The race was there and was fixed by commit 

| commit 34adc8062227f41b04ade0ff3fbd1dbe3002669e
| Author: Ingo Molnar <mingo@...e.hu>
| Date:   Wed May 20 20:13:28 2009 +0200

then you fixed it further in commit

| commit 3fb2b8ddcc6a7aa62af6bd2cb939edfd4c460506
| Author: Peter Zijlstra <a.p.zijlstra@...llo.nl>
| Date:   Mon Mar 8 13:51:01 2010 +0100

which I understand as we don't need perf_disable here for sure.
Just for the record :)

	-- Cyrill
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