From: "Jan Beulich" <JBeulich@suse.com>
To: David Vrabel <david.vrabel@citrix.com>
Cc: xen-devel@lists.xenproject.org, Keir Fraser <keir@xen.org>
Subject: Re: [PATCH 3/4] x86/nmi: wait for all CPUs in check_nmi_watchdog()
Date: Wed, 14 May 2014 14:59:58 +0100 [thread overview]
Message-ID: <537392FE02000078000123AD@mail.emea.novell.com> (raw)
In-Reply-To: <1400072299-2285-4-git-send-email-david.vrabel@citrix.com>
>>> On 14.05.14 at 14:58, <david.vrabel@citrix.com> wrote:
> The counting of a CPUs NMIs in check_nmi_watchdog() is only reliable
> if all CPUs have been spinning for 5 or more ticks. There may be
> delays in waking other CPUs from deep power states that can mean that
> when the counts are checked CPUs haven't run for long enough.
5 ticks ought to be a couple of orders of a magnitude longer than
the worst possible wakeup time. I.e. I don't buy this argument
without actual numbers to support it.
Jan
next prev parent reply other threads:[~2014-05-14 14:00 UTC|newest]
Thread overview: 20+ messages / expand[flat|nested] mbox.gz Atom feed top
2014-05-14 12:58 [PATCH 0/4] x86/nmi: improve NMI watchdog test David Vrabel
2014-05-14 12:58 ` [PATCH 1/4] x86/nmi: remove spurious local_irq_enable from check_nmi_watchdog() David Vrabel
2014-05-14 13:25 ` Jan Beulich
2014-05-14 13:31 ` David Vrabel
2014-05-14 13:53 ` Jan Beulich
2014-05-15 11:40 ` Tim Deegan
2014-05-14 12:58 ` [PATCH 2/4] x86/nmi: enable local irqs in wait_for_nmis() David Vrabel
2014-05-14 13:57 ` Jan Beulich
2014-05-14 14:38 ` David Vrabel
2014-05-14 14:45 ` Jan Beulich
2014-05-15 11:55 ` Tim Deegan
2014-05-14 12:58 ` [PATCH 3/4] x86/nmi: wait for all CPUs in check_nmi_watchdog() David Vrabel
2014-05-14 13:59 ` Jan Beulich [this message]
2014-05-14 14:09 ` David Vrabel
2014-05-14 14:33 ` Jan Beulich
2014-05-14 14:09 ` Andrew Cooper
2014-05-15 11:47 ` Tim Deegan
2014-05-14 12:58 ` [PATCH 4/4] x86/nmi: be less verbose when testing the NMI watchdog David Vrabel
2014-05-15 11:48 ` Tim Deegan
2014-05-14 13:03 ` [PATCH 0/4] x86/nmi: improve NMI watchdog test Andrew Cooper
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