Re: CPU utilization never goes above 50% in Fortran code
From: John C. Bollinger (jobollin_at_indiana.edu)
Date: 11/01/04
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Date: Mon, 01 Nov 2004 08:34:26 -0500
Chandra Chilmakuri wrote:
> I think hyperthreading of your processor is switched on, which would
> divide your processor into two (50% each). you can disable this going
> to setup while your machine is booting.
This sounds a bit deceptive, as if having hyperthreading enabled would
halve performance. That would be extremely unlikely, but what HT
_could_ do is confuse a process monitor into thinking that your program
was only using 50% of the available CPU power. You can check whether HT
is behind the observed behavior by disabling it as Chandra said. I
would recommend that you test your applications with HT on and off to
satisfy yourself as to which configuration produces the better
performance. If they are about the same then you should probably leave
HT on.
John Bollinger
jobollin@indiana.edu
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