From: "David S. Miller" <davem@redhat.com>
To: alan@lxorguk.ukuu.org.uk
Cc: ak@suse.de, linux-kernel@vger.kernel.org, johnstul@us.ibm.com,
anton.wilson@camotion.com
Subject: Re: do_gettimeofday vs. rdtsc in the scheduler
Date: Tue, 17 Sep 2002 14:18:06 -0700 (PDT) [thread overview]
Message-ID: <20020917.141806.49377410.davem@redhat.com> (raw)
In-Reply-To: <1032298092.20498.21.camel@irongate.swansea.linux.org.uk>
From: Alan Cox <alan@lxorguk.ukuu.org.uk>
Date: 17 Sep 2002 22:28:12 +0100
A bus clock - but things like the x440 have more than one bus clock. Its
NUMA. Also the bus clock and rdtsc clock are different - rdtsc is
dependant on the multiplier. Shove a celeron 300 and a celeron 450 in a
BP6 board with tsc on and enjoy
That's mostly my point.
If the bus clocks differ, then great create some system wide crystal
oscillator. That's a detail, the important bit is that you don't need
to go out to the system bus to read the tick value, it must be cpu
local to be effective and without serious performance impact.
next prev parent reply other threads:[~2002-09-17 21:22 UTC|newest]
Thread overview: 29+ messages / expand[flat|nested] mbox.gz Atom feed top
[not found] <200209172020.g8HKKPF13227@eng2.beaverton.ibm.com.suse.lists.linux.kernel>
[not found] ` <1032294559.22815.180.camel@cog.suse.lists.linux.kernel>
[not found] ` <20020917.133933.69057655.davem@redhat.com.suse.lists.linux.kernel>
2002-09-17 21:00 ` do_gettimeofday vs. rdtsc in the scheduler Andi Kleen
2002-09-17 20:54 ` David S. Miller
2002-09-17 21:28 ` Alan Cox
2002-09-17 21:18 ` David S. Miller [this message]
2002-09-17 22:02 ` James Cleverdon
2002-09-17 22:44 ` Andi Kleen
2002-09-17 22:38 ` David S. Miller
2002-09-17 22:55 ` James Cleverdon
2002-09-17 23:12 ` David S. Miller
2002-09-17 23:32 ` john stultz
2002-09-17 23:32 ` David S. Miller
2002-09-17 23:52 ` Andi Kleen
2002-09-17 23:46 ` David S. Miller
2002-09-17 23:58 ` Andi Kleen
2002-09-17 23:51 ` David S. Miller
2002-09-18 0:05 ` Andi Kleen
2002-09-18 1:04 ` James Cleverdon
2002-09-19 18:02 ` Andrea Arcangeli
2002-09-20 11:04 ` Maciej W. Rozycki
2002-09-19 11:20 ` Mikael Pettersson
2002-09-19 13:27 ` Alan Cox
2002-09-19 13:39 ` Mikael Pettersson
2002-09-20 15:26 ` John Levon
2002-09-18 6:40 ` Vojtech Pavlik
2002-09-19 18:04 ` Andrea Arcangeli
[not found] <200209172020.g8HKKPF13227@eng2.beaverton.ibm.com>
2002-09-17 20:29 ` Fwd: " john stultz
2002-09-17 20:39 ` David S. Miller
2002-09-17 20:57 ` john stultz
2002-09-17 20:56 ` David S. Miller
2002-09-09 22:21 anton wilson
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