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From: Peter Zijlstra <>
To: Zhao Forrest <>
Subject: Re: Can Linux kernel handle unsynced TSC?
Date: Fri, 29 Feb 2008 11:43:43 +0100	[thread overview]
Message-ID: <1204281823.6243.78.camel@lappy> (raw)
In-Reply-To: <>

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.

  reply	other threads:[~2008-02-29 10:43 UTC|newest]

Thread overview: 4+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2008-02-29  8:55 Zhao Forrest
2008-02-29 10:43 ` Peter Zijlstra [this message]
2008-02-29 14:20   ` Zhao Forrest
2008-02-29 14:27     ` Peter Zijlstra

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