Message-ID: <45694D6F.60100@saville.com>
Date: Sun, 26 Nov 2006 00:16:47 -0800
From: Wink Saville <wink@saville.com>
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To: Robert Hancock <hancockr@shaw.ca>
CC: linux-kernel <linux-kernel@vger.kernel.org>,
       Arjan van de Ven <arjan@infradead.org>
Subject: Re: [patch] x86: unify/rewrite SMP TSC sync code
References: <fa./NRPJg+JjfSQLUVwnX1GpHGIojQ@ifi.uio.no> <fa.Y0RKABHd+7qnbGQYBAGPvlJ0Qic@ifi.uio.no> <fa.fD3WSpNqEJ4736vYzEak5Gf3xTw@ifi.uio.no> <fa.A+gkQAO1DLThaxJxPLPl3yE1CGo@ifi.uio.no> <fa.INurNKWdUKAEULTHyfpSW65a/Ng@ifi.uio.no> <fa.n9vySiI9RS2MCl0DZPDzxZEPiFw@ifi.uio.no> <4569404E.20402@shaw.ca>
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Robert Hancock wrote:
>>>> Actually, we need to ask the CPU/System makers to provide a system wide
> Generally user mode code should just be using gettimeofday. When the TSC 
> is usable as a sane time source, the kernel will use it. When it's not, 
> it will use something else like the HPET, ACPI PM Timer or (at last 
> resort) the PIT, in increasing degrees of slowness.
> 

But gettimeofday is much too expensive compared to RDTSC.

Wink

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