linux-kernel - Re: [PATCH]x86, reboot: Fix a warning message triggered by stop_other

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Date:	Mon, 28 May 2012 09:22:09 +0800
From:	Feng Tang <feng.tang@...el.com>
To:	Don Zickus <dzickus@...hat.com>
Cc:	Ingo Molnar <mingo@...e.hu>, Peter Zijlstra <peterz@...radead.org>,
	<x86@...nel.org>, <linux-kernel@...r.kernel.org>
Subject: Re: [PATCH]x86, reboot: Fix a warning message triggered by
 stop_other_cpus()

Hi Don,

On Tue, 22 May 2012 09:33:56 -0400
Don Zickus <dzickus@...hat.com> wrote:

> On Tue, May 22, 2012 at 10:52:33AM +0800, Feng Tang wrote:
> > 
> > The root cause seems to be the default_send_IPI_mask_allbutself_phys()
> > takes quiet some time (I measured it could be several ms) to complete
> > sending NMIs to all the other 23 CPUs, and for HZ=250/1000 system, the
> 
> I sent Ingo a patch (which he took in), that reverts this path to interrupts
> again (and NMIs as a fallback if it fails).  The problem will still exist
> I assume though I don't know if it changes the timing characteristics.

Thanks for your review and letting me know the revert which I just saw in
the latest Linus' tree. And I think this new mechanism will greatly reduce
the possibility, but it still exist as the old nmi_stop_other_cpus's
implementation still exist. So

Ingo,

Could you review this patch? thanks,

-Feng

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