linux-kernel - Re: [V3][PATCH 0/6] x86, nmi: new NMI handling routines

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Message-ID: <20110906164337.GK14200@erda.amd.com>
Date:	Tue, 6 Sep 2011 18:43:37 +0200
From:	Robert Richter <robert.richter@....com>
To:	Don Zickus <dzickus@...hat.com>
CC:	"x86@...nel.org" <x86@...nel.org>,
	Andi Kleen <andi@...stfloor.org>,
	Peter Zijlstra <peterz@...radead.org>,
	"ying.huang@...el.com" <ying.huang@...el.com>,
	LKML <linux-kernel@...r.kernel.org>,
	"paulmck@...ux.vnet.ibm.com" <paulmck@...ux.vnet.ibm.com>
Subject: Re: [V3][PATCH 0/6] x86, nmi: new NMI handling routines

On 25.08.11 12:45:42, Don Zickus wrote:
> I had the pleasure of hosting Robert Richter this week at Red Hat.  One of
> the issues he wanted to talk with me about was having the NMI handling 
> routines execute all the NMI handlers for each NMI mainly for his AMD IBS
> work.  But he also brought up another good point that because of the way NMIs
> work, it is possible to lose them if multiple NMIs happen at the same time.
> 
> As a result, we sat around and discussed how we could go about executing
> all the nmi handlers for each NMI to ensure that we would not lose any events.
> 
> We decided the best way to do this would be to have the NMI handlers break
> away from the notifier routines and create our own.  This would allow us to
> execute all the handlers without hacking up the notifier stuff and easily
> track the number of events processed at a higher level to deal with the new
> problemm of extra NMIs.
> 
> I spent some time hacking and came up with this patch.  I tested it on my
> core2quad machine trying to enable all the NMI handler I could, mainly
> perf and kgdb (and oprofile too when perf was disabled).  Everything seems
> to work correctly.  If people are ok with this approach, I'll try and test
> this on more machines.
> 
> More details about the patch are in the individual changelogs.

Don,

thanks for this patch set. So far it looks good to me. See my comments
posted. I don't think they require necessarily a new patch
version. Instead we could implement changes on top of it.

I will rebase my current perf ibs implementation on to of this
patches. It would be good to have the patches in tip after kernel.org
is back again.

Thanks,

-Robert

-- 
Advanced Micro Devices, Inc.
Operating System Research Center

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