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Date: Thu, 10 Apr 2008 13:52:28 -0700
From: Maxim Sobolev <sobomax@FreeBSD.org>
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To: Kris Kennaway <kris@FreeBSD.org>
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Cc: gnn@FreeBSD.org, current@FreeBSD.org
Subject: Re: TSC Timecounter and multi-core/SMP
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Kris Kennaway wrote:
> gnn@freebsd.org wrote:
>> Howdy,
>>
>> Is the TSC timecounter synchronized across multiple cores and/or
>> processors?  A quick search seems to indicate it's not but I'd like to
>> find a definitive reference on the TSC.
> 
> Modern Intel systems tend to be synchronized, in my experience.

I really doubt they are. As far as I know newest milti-core chips can 
modulate frequency of even suspend individual cores independently of 
each other, which would make such synchronization difficult to maintain 
if the power management is on.

-Maxim