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From: Andi Kleen <ak@suse.de>
To: Thomas Gleixner <tglx@linutronix.de>
Cc: Arjan van de Ven <arjan@infradead.org>,
	David Bahi <dbahi@novell.com>,
	LKML <linux-kernel@vger.kernel.org>,
	linux-rt-users@vger.kernel.org,
	Andrew Morton <akpm@linux-foundation.org>,
	Ingo Molnar <mingo@elte.hu>,
	Gregory Haskins <GHaskins@novell.com>
Subject: Re: nmi_watchdog fix for x86_64 to be more like i386
Date: Mon, 1 Oct 2007 23:41:52 +0200	[thread overview]
Message-ID: <200710012341.53169.ak@suse.de> (raw)
In-Reply-To: <alpine.LFD.0.9999.0710012207270.20478@localhost.localdomain>


> IRQ_NOBALANCING is not preventing cpu unplug. It moves the affinity to the
> next CPU, but the check in NMI watchdog for CPU == 0 would not longer
> work.

That cannot happen right now because cpu_disable() on both i386/x86-64
reject CPU #0. So just setting IRQ_NOBALANCING is sufficient and both
do that already. I was wrong earlier in being concerned about this.

>  int tick_do_broadcast(cpumask_t mask)
> @@ -137,6 +147,7 @@ int tick_do_broadcast(cpumask_t mask)
>  		cpu_clear(cpu, mask);
>  		td = &per_cpu(tick_cpu_device, cpu);
>  		td->evtdev->event_handler(td->evtdev);
> +		tick_broadcast_account(cpu);

That would not handle the case with a single CPU running only
irq  0 but not broadcasting I think.

I believe ftp://ftp.firstfloor.org/pub/ak/x86_64/quilt/patches/fix-watchdog
is the correct fix

-Andi

  reply	other threads:[~2007-10-01 21:43 UTC|newest]

Thread overview: 24+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2007-09-26 18:03 nmi_watchdog fix for x86_64 to be more like i386 David Bahi
2007-10-01 17:36 ` Andi Kleen
2007-10-01 18:54   ` Thomas Gleixner
2007-10-01 19:16     ` Andi Kleen
2007-10-01 19:27       ` Thomas Gleixner
2007-10-01 19:56         ` Arjan van de Ven
2007-10-01 20:10           ` Dave Jones
2007-10-01 20:11           ` Paul E. McKenney
2007-10-01 21:17           ` Thomas Gleixner
2007-10-01 21:41             ` Andi Kleen [this message]
2007-10-01 21:58               ` Thomas Gleixner
2007-10-01 22:07                 ` Andi Kleen
2007-10-01 22:47                   ` Thomas Gleixner
2007-10-01 22:52                     ` Arjan van de Ven
2007-10-02  4:56                     ` Mika Penttilä
2007-10-02  5:00                       ` Arjan van de Ven
2007-10-02  5:51                     ` Andi Kleen
2007-10-02  6:18                       ` Thomas Gleixner
2007-10-05  4:37                         ` Pallipadi, Venkatesh
2007-10-05 20:37                           ` Thomas Gleixner
  -- strict thread matches above, loose matches on Subject: below --
2007-10-05 16:01 David Bahi
2007-10-05 16:03 ` Andi Kleen
2007-10-05 17:38   ` Peter W. Morreale
2007-10-05 18:00     ` Andi Kleen

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