Re: HT Benchmarks (was: /proc/cpuinfo and hyperthreading)

From: Andrew Burgess (
Date: Wed Dec 18 2002 - 12:56:56 EST

>Number of threads Elapsed time User Time System Time
>1 53:216 53:220 00:000
>2 29:272 58:180 00:320
>3 27:162 1:21:450 00:540
>4 25:094 1:41:080 01:250

>Elapsed is measured by the parent thread, that is not doing anything
>but wait on a pthread_join. User and system times are the sum of
>times for all the children threads, that do real work.

>The jump from 1->2 threads is fine, the one from 2->4 is ridiculous...
>I have my cpus doubled but each one has half the pipelining for floating
>point...see the user cpu time increased due to 'worst' processors and
>cache pollution on each package.

>So, IMHO and for my apps, HyperThreading is just a bad joke.

Why do you care about user time? The elapsed time went down by
4 minutes (2->4 threads), if that's a joke I don't get it :-)

New Intel Ad: "What are you going to do with your 4 minutes today?"

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This archive was generated by hypermail 2b29 : Mon Dec 23 2002 - 22:00:20 EST