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Message-ID: <20070719145058.GA11971@elte.hu>
Date: Thu, 19 Jul 2007 16:50:58 +0200
From: Ingo Molnar <mingo@...e.hu>
To: Jeremy Fitzhardinge <jeremy@...p.org>
Cc: Andrew Morton <akpm@...ux-foundation.org>,
linux-kernel@...r.kernel.org,
Linus Torvalds <torvalds@...ux-foundation.org>,
stable@...nel.org, Greg KH <greg@...ah.com>,
Chris Wright <chrisw@...s-sol.org>
Subject: Re: [patch] fix the softlockup watchdog to actually work
* Jeremy Fitzhardinge <jeremy@...p.org> wrote:
> Hm, or more specifically, why would that be a problem for softlockup?
> Do you mean it doesn't measure time during ACPI idle? That would just
> make it trigger later than it would otherwise.
no, the return value after idling can be completely random on some
boxes, on a 64-bit scale - triggering the softlockup watchdog randomly.
(some boxes return random TSC values, etc.) Again, it's fine for the
scheduler's purpose, that's why i named it sched_clock().
the proper clocksource use within the kernel is ktime_get() [or
ktime_get_ts()]. Do not abuse sched_clock() for such things.
Ingo
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