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Date: Wed, 3 Dec 2014 16:19:57 -0800
Message-ID: <CA+55aFyaRByi2NLb7YZ_jHnHc6VTb-Ht748ZVVfa-XC7sdqL-g@mail.gmail.com>
Subject: Re: frequent lockups in 3.18rc4
From: Linus Torvalds <torvalds@linux-foundation.org>
To: Thomas Gleixner <tglx@linutronix.de>
Cc: Dave Jones <davej@redhat.com>, Chris Mason <clm@fb.com>,
        Mike Galbraith <umgwanakikbuti@gmail.com>,
        Ingo Molnar <mingo@kernel.org>, Peter Zijlstra <peterz@infradead.org>,
        =?UTF-8?Q?D=C3=A2niel_Fraga?= <fragabr@gmail.com>,
        Sasha Levin <sasha.levin@oracle.com>,
        "Paul E. McKenney" <paulmck@linux.vnet.ibm.com>,
        Linux Kernel Mailing List <linux-kernel@vger.kernel.org>,
        John Stultz <john.stultz@linaro.org>
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Sender: linux-kernel-owner@vger.kernel.org

On Wed, Dec 3, 2014 at 3:49 PM, Thomas Gleixner <tglx@linutronix.de> wrote:
>
> Bah. Would have been too simple ....

I do think you tend to trust the hpet too much.

Yes, we've had issues with people doing bad things to the tsc, but on
the whole I really would tend to trust the internal CPU counter a
_lot_ more than the external hpet.

So I think it's equally (if not more) likely that switching from tsc
to hpet causes trouble, because I'd trust the tsc more than the hpet.

DaveJ, do this:

> Could you please run Ingos time-warp test on that machine for a while?

but perhaps also boot with "tsc=reliable", which _should_ get rid of
that CLOCK_SOURCE_MUST_VERIFY, and the clocksource watchdog should do
nothing.

Thomas? Am I misreading that?

              Linus
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