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

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Date:	Sat, 26 Mar 2011 10:44:20 +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 Sat, 2011-03-26 at 09:15 +0100, Eric Dumazet wrote:
> Le vendredi 25 mars 2011 à 21:29 +0100, Peter Zijlstra a écrit :
> > 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
> > 
> > 
> > 
> 
> Thanks Peter !
> 
> I was not aware of the hidden "CTRL-A" feature on RBSU, so I never met
> these configuration settings ("Service Options" added in main menu)
> 
> I already was in "Power regulator mode : Static High mode"
> QPI Link power management : Disabled
> 
> I have latest released I24 BIOS
> DMI: HP ProLiant BL460c G6, BIOS I24 01/29/2011
> 
> 1) I disabled "Power and Utilization Monitoring" _and_ "Memory
> Pre-Failure Notification"
> 
> Still I got the 'MSR 38d is 330' error
> 
> 2) I then disabled Intel Turbo boost
> 
> Same error
> 
> 3) Minimum Processor idle Power state
>   From C1E-State --> No C-states
> 
> Same error
> 
> Tricky isnt it ?

Definitely, OK thanks for testing, I'll contact HP again.

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