From: Andrew Morton <akpm@linux-foundation.org>
To: Anshuman Khandual <khandual@linux.vnet.ibm.com>
Cc: Sameer Nanda <snanda@chromium.org>,
mingo@redhat.com, peterz@infradead.org, len.brown@intel.com,
pavel@ucw.cz, rjw@sisk.pl, dzickus@redhat.com, msb@chromium.org,
linux-kernel@vger.kernel.org, linux-pm@vger.kernel.org,
olofj@chromium.org,
"Srivatsa S. Bhat" <srivatsa.bhat@linux.vnet.ibm.com>
Subject: Re: [PATCH v2] watchdog: fix for lockup detector breakage on resume
Date: Fri, 8 Jun 2012 14:44:47 -0700 [thread overview]
Message-ID: <20120608144447.b8e2d146.akpm@linux-foundation.org> (raw)
In-Reply-To: <4FA74089.4080204@linux.vnet.ibm.com>
On Mon, 07 May 2012 08:54:57 +0530
Anshuman Khandual <khandual@linux.vnet.ibm.com> wrote:
> On Tuesday 01 May 2012 10:52 PM, Sameer Nanda wrote:
>
> > On the suspend/resume path the boot CPU does not go though an
> > offline->online transition. This breaks the NMI detector
> > post-resume since it depends on PMU state that is lost when
> > the system gets suspended.
>
>
> We should not have allowed the PMU to go with events counting on it across the suspend/resume transition
> and find out that the state has been lost. This patch solves the problem of the NMI detector as we restart the
> counter again when the boot cpu comes back online during resume. But the original cause (PMU going with
> counters into the suspend state) which triggered this problem is still there. May be we should have called
> perf_event_exit() on the boot cpu before going into the suspend state.
>
That sounds like a nicer solution.
An implementation would be nice ;) I'll keep the original patch on life
support until we get all this nailed down.
prev parent reply other threads:[~2012-06-08 21:44 UTC|newest]
Thread overview: 14+ messages / expand[flat|nested] mbox.gz Atom feed top
2012-04-27 18:10 [PATCH] watchdog: fix for lockup detector breakage on resume Sameer Nanda
2012-04-27 21:12 ` Andrew Morton
2012-04-27 21:33 ` Rafael J. Wysocki
2012-04-27 21:40 ` Sameer Nanda
2012-04-27 22:03 ` Andrew Morton
2012-04-27 22:20 ` Sameer Nanda
2012-04-30 6:12 ` Srivatsa S. Bhat
2012-04-30 13:05 ` Don Zickus
2012-04-30 21:10 ` Sameer Nanda
2012-05-01 17:25 ` Sameer Nanda
2012-05-02 13:14 ` Srivatsa S. Bhat
2012-05-01 17:22 ` [PATCH v2] " Sameer Nanda
2012-05-07 3:24 ` Anshuman Khandual
2012-06-08 21:44 ` Andrew Morton [this message]
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