Re: Timer updates revision 7 (asm sets predicates/various fixes)

From: David Mosberger <davidm_at_napali.hpl.hp.com>
Date: 2004-08-02 19:36:17
>>>>> On Fri, 30 Jul 2004 08:34:56 -0700 (PDT), Christoph Lameter <clameter@sgi.com> said:

  >> The numbers above indicate a substantial slowdown going from 1 to
  >> 2 cpus. What happens at higher cpu counts.

  Christoph> The code that uses cmpxchg will always be a scalability
  Christoph> issue.

Also, you need to keep things in perspective: the test programs
_continually_ bangs on gettimeofday().  If the cmpxchg were a
scalability issue for, say, 16-32-way machines with _real_ workloads,
I'd really be surprised.  Now if you have 128 or more CPUs, I do agree
that the picture would be very different and scalability is a much
bigger concern.

	--david
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Received on Mon Aug 2 05:36:29 2004

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