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From: Thomas Gleixner <tglx@linutronix.de>
To: Andi Kleen <andi@firstfloor.org>
Cc: Dave Kleikamp <dkleikamp@gmail.com>,
	Chris Mason <chris.mason@oracle.com>,
	Peter Zijlstra <a.p.zijlstra@chello.nl>,
	Tim Chen <tim.c.chen@linux.intel.com>,
	linux-kernel@vger.kernel.org, lenb@kernel.org,
	paulmck@us.ibm.com
Subject: Re: idle issues running sembench on 128 cpus
Date: Thu, 5 May 2011 15:58:19 +0200 (CEST)	[thread overview]
Message-ID: <alpine.LFD.2.02.1105051556580.3005@ionos> (raw)
In-Reply-To: <alpine.LFD.2.02.1105050110440.3005@ionos>

On Thu, 5 May 2011, Thomas Gleixner wrote:
> On Thu, 5 May 2011, Andi Kleen wrote:
> > > No, it does not even need refcounting. We can access it outside of the
> > 
> > Ok.
> > 
> > > lock as this is atomic context called on the cpu which is about to go
> > > idle and therefor the device cannot go away. Easy and straightforward
> > > fix.
> > 
> > Ok. Patch appended. Looks good?
> 
> Mostly. See below.
>  
> > BTW why must the lock be irqsave?
> 
> Good question. Probably safety frist paranoia :)
> 
> Indeed that code should only be called from irq disabled regions, so
> we could avoid the irqsave there. Otherwise that needs to be irqsave
> for obvious reasons.

Just looked through all the call sites. Both intel_idle and
processor_idle notify ENTER with interrups disabled, but EXIT with
interrupts enabled. So when we want to remove irqsave from the
spinlock that needs to be fixed as well.

Thanks,

        tglx

      parent reply	other threads:[~2011-05-05 13:58 UTC|newest]

Thread overview: 13+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2011-05-04 21:47 idle issues running sembench on 128 cpus Dave Kleikamp
2011-05-04 22:04 ` Thomas Gleixner
2011-05-04 22:07 ` Andi Kleen
2011-05-04 22:34   ` Thomas Gleixner
2011-05-04 23:03     ` Andi Kleen
2011-05-04 23:29       ` Thomas Gleixner
2011-05-04 23:42         ` Andi Kleen
2011-05-04 23:47           ` Thomas Gleixner
2011-05-04 23:49             ` Andi Kleen
2011-05-04 23:51               ` Thomas Gleixner
2011-05-04 23:48           ` idle issues running sembench on 128 cpus II Andi Kleen
2011-05-05 15:24             ` Dave Kleikamp
2011-05-05 13:58         ` Thomas Gleixner [this message]

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