linux-kernel - Re: gettimeofday() resolution in Linux?

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Message-ID: <87fxttn2o2.fsf@basil.nowhere.org>
Date:	Thu, 10 Apr 2008 17:35:25 +0200
From:	Andi Kleen <andi@...stfloor.org>
To:	lsorense@...lub.uwaterloo.ca (Lennart Sorensen)
Cc:	Jack Harvard <jack.harvard@...glemail.com>,
	linux-kernel@...r.kernel.org
Subject: Re: gettimeofday() resolution in Linux?

lsorense@...lub.uwaterloo.ca (Lennart Sorensen) writes:
>
> On many systems gettimeofday uses the TSC, but on many multicore systems
> the TSC on each core may be out of sync, in which case the cpu you are
> running on may give a different gettimeofday result than another cpu,
> which is probably a bad thing for some processes.

In this case Linux falls back to other timers which are slower and 
less accurate.

jiffies based gettimeofday is theoretically possible, but near
never used.

-Andi
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