From mboxrd@z Thu Jan  1 00:00:00 1970
From: Peter Zijlstra <peterz@infradead.org>
Subject: Re: Can Linux kernel handle unsynced TSC?
Date: Fri, 29 Feb 2008 11:43:43 +0100
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Cc: kvm-devel@lists.sourceforge.net, linux-kernel@vger.kernel.org
To: Zhao Forrest <forrest.zhao@gmail.com>
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On Fri, 2008-02-29 at 16:55 +0800, Zhao Forrest wrote:
> Sorry for reposting it.
> 
> For example,
> 1 rdtsc() is invoked on CPU0
> 2 process is migrated to CPU1, and rdtsc() is invoked on CPU1
> 3 if TSC on CPU1 is slower than TSC on CPU0, can kernel guarantee
> that the second rdtsc() doesn't return a value smaller than the one
> returned by the first rdtsc()?

No, rdtsc() goes directly to the hardware. You need a (preferably cheap)
clock abstraction layer on top if you need this.


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