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From: Don Zickus <dzickus@redhat.com>
To: ZAK Magnus <zakmagnus@google.com>
Cc: linux-kernel@vger.kernel.org, Ingo Molnar <mingo@elte.hu>,
	Mandeep Singh Baines <msb@chromium.org>
Subject: Re: [PATCH v3 2/2] Make hard lockup detection use timestamps
Date: Wed, 3 Aug 2011 15:44:38 -0400	[thread overview]
Message-ID: <20110803194438.GA20762@redhat.com> (raw)
In-Reply-To: <CAAuSN92zumHAOvthSYEQ5FqjpX_p2uw_WhDCb4ubHtEg9+vbpg@mail.gmail.com>

On Wed, Aug 03, 2011 at 11:27:16AM -0700, ZAK Magnus wrote:
> An update:
> 
> I realized that the timing function I was using was no good. On x86 it
> will try to use the TSC but if it can't (which, as I understand, isn't
> a very rare case), it will fall back on a jiffies-based solution. If
> interrupts are disabled, time would appear to "stand still" and
> lockups wouldn't be detected. So, looks like I have to nix this
> particular patch and not change the hard lockup detection that much.

Hmm, I was initially worried about that, but after seeing the function
you were using assuming Peter vetted it properly to use cleanly from an
NMI context.  I guess I didn't fully understand the limitations of it.

> 
> Meanwhile, I'm working on printing stack traces to a buffer/out to
> file. I got some help and it looks like it's not that hard to do. I'll
> send it when it's ready.

Interesting.  I look forward to seeing it.

Cheers,
Don


  reply	other threads:[~2011-08-03 19:45 UTC|newest]

Thread overview: 15+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2011-07-21 18:11 [PATCH v3 2/2] Make hard lockup detection use timestamps Alex Neronskiy
2011-07-22 19:53 ` Don Zickus
2011-07-22 22:34   ` ZAK Magnus
2011-07-25 12:44     ` Don Zickus
2011-07-29  0:16       ` ZAK Magnus
2011-07-29 13:10         ` Don Zickus
2011-07-29 20:55         ` Don Zickus
2011-07-29 23:12           ` ZAK Magnus
2011-08-01 12:52             ` Don Zickus
2011-08-01 18:33               ` ZAK Magnus
2011-08-01 19:24                 ` Don Zickus
2011-08-01 20:11                   ` ZAK Magnus
2011-08-03 18:27                     ` ZAK Magnus
2011-08-03 19:44                       ` Don Zickus [this message]
2011-08-03 19:11                     ` Don Zickus

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