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    SubjectRE: constant_tsc and TSC unstable
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    >-----Original Message-----
    >From: linux-kernel-owner@vger.kernel.org
    >[mailto:linux-kernel-owner@vger.kernel.org] On Behalf Of Paul
    >Rolland (???・???)
    >Sent: Thursday, November 29, 2007 8:12 AM
    >To: Linux Kernel
    >Cc: rol@witbe.net
    >Subject: constant_tsc and TSC unstable
    >
    >Hello,
    >
    >I've a machine with a Core2Duo CPU. /proc/cpuinfo reports the flag
    >constant_tsc, but at boot time, I have the log :
    >
    >...
    >Total of 2 processors activated (6919.15 BogoMIPS).
    >ENABLING IO-APIC IRQs
    >..TIMER: vector=0x31 apic1=0 pin1=2 apic2=-1 pin2=-1
    >checking TSC synchronization [CPU#0 -> CPU#1]:
    >Measured 3978592228 cycles TSC warp between CPUs, turning off
    >TSC clock.
    >Marking TSC unstable due to: check_tsc_sync_source failed.
    >Brought up 2 CPUs
    >...
    >
    >This machine is running 2.6.23.1-21.fc7. I know I should
    >report to Fedora,
    >but I was wondering if this is a bug or a feature ;)
    >

    TSCs on Core 2 Duo are supposed to be in sync unless CPU supports deep idle states like C2, C3. Can you send the full /proc/cpuinfo and full dmesg.

    Thanks,
    Venki
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