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From: "David S. Miller" <davem@redhat.com>
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Date: Mon, 30 Apr 2001 00:02:27 -0700 (PDT)
To: dean gaudet <dean-list-linux-kernel@arctic.org>
Cc: Jeff Garzik <jgarzik@mandrakesoft.com>, "H. Peter Anvin" <hpa@zytor.com>,
        <linux-kernel@vger.kernel.org>
Subject: Re: X15 alpha release: as fast as TUX but in user space (fwd)
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dean gaudet writes:
 > i was kind of solving a different problem with the code page though -- the
 > ability to use rdtsc on SMP boxes with processors of varying speeds and
 > synchronizations.

A better way to solve that problem is the way UltraSPARC-III do and
future ia64 systems will, by way of a "system tick" register which
increments at a constant rate regardless of how the cpus are clocked.

The "system tick" pulse goes into the processor, so it's still a local
cpu register being accessed.  Think of it as a system bus clock cycle
counter.

Granted, you probably couldn't make changes to the hardware you were
working on at the time :-)

Later,
David S. Miller
davem@redhat.com

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