linux-kernel - Re: [PATCH RFC] x86: avoid atomic operation in test_and_set_bit

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Date:	Fri, 25 Mar 2011 21:29:40 +0100
From:	Peter Zijlstra <a.p.zijlstra@...llo.nl>
To:	Eric Dumazet <eric.dumazet@...il.com>
Cc:	Andi Kleen <andi@...stfloor.org>,
	Linus Torvalds <torvalds@...ux-foundation.org>,
	Ingo Molnar <mingo@...e.hu>, Jack Steiner <steiner@....com>,
	Jan Beulich <JBeulich@...ell.com>,
	Borislav Petkov <bp@...64.org>,
	Nick Piggin <npiggin@...nel.dk>,
	"x86@...nel.org" <x86@...nel.org>,
	Thomas Gleixner <tglx@...utronix.de>,
	Andrew Morton <akpm@...ux-foundation.org>,
	Ingo Molnar <mingo@...hat.com>, tee@....com,
	Nikanth Karthikesan <knikanth@...e.de>,
	"linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
	"H. Peter Anvin" <hpa@...or.com>
Subject: Re: [PATCH RFC] x86: avoid atomic operation in
 test_and_set_bit_lock if possible

On Fri, 2011-03-25 at 10:38 +0100, Eric Dumazet wrote:
> 
> BIOS :  Version: I27  Release Date: 09/30/2010
> 
> [    0.021849] CPU0: Intel(R) Xeon(R) CPU           E5640  @ 2.67GHz stepping 02
> [    0.123904] Performance Events: PEBS fmt1+, Westmere events, Broken BIOS detected, using software events only.
> [    0.124125] [Firmware Bug]: the BIOS has corrupted hw-PMU resources (MSR 38d is 330) 

Do the below instructions yield a working system?:

> > On the BL460c G6/G7, one could perform the following steps:
> >
> > To configure BIOS low-latency options using RBSU
> > 1. Press F9 during POST to enter RBSU.
> > 2. Press CTRL-A to open the menu.
> > 3. Select Service Options.
> > 4. Disable either or both of the following options:
> > o Processor Power and Utilization Monitoring
> > o Memory Pre-Failure Notification
> > 
> > By doing the above the BIOS should release the performance counter, and the
> > kernel's "perf" should not encounter a conflict. 
> > 
> > The document that you are looking for is here: (please see page 8 and later):
> > http://h20000.www2.hp.com/bc/docs/support/SupportManual/c01804533/c01804533.pdf



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