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

J.A. Magallon (
Thu, 19 Dec 2002 23:04:55 +0100

On 2002.12.18 Andrew Burgess wrote:
>>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?"

Of course I gain something. The problem is the price you pay for the

Prices in Spain: a P4 with 512Kb cache, 210 euros. Equal features (freq,
cache), but Xeon version, 320 euros. So you pay 50% more money for
10% more performance. Not too fair...

J.A. Magallon <>      \                 Software is like sex:                         \           It's better when it's free
Mandrake Linux release 9.1 (Cooker) for i586
Linux 2.4.20-jam2 (gcc 3.2 (Mandrake Linux 9.1 3.2-4mdk))
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