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From: Rolf Campbell <Endlisnis AT mailc DOT net>
Subject: Re: two instances of a.exe on dual processor - still only 50% performance
Date: Wed, 07 Jul 2004 13:57:14 -0400
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Ken Thompson wrote:
> At 01:24 PM 7/7/2004, Rolf Campbell wrote:
>>
>> Sorry Brian, that is bogus.  I'm running one HT processor right now. 
>> The combined CPU utilization is not an actual display of usage, but 
>> theoretical usage, based on scheduling.  It's really how much of the 
>> CPU was NOT being used by the idle task, and given that there is only 
>> one CPU, if some process is taking up 99% of it, and some other 
>> process takse up the other 1% on the other 'hyper thread' then the 
>> idle task will not be able to run at all on either virtual cpu.  Thus 
>> Task Manager will (and does) show 100% dual CPU utilization.
>>
>> -Rolf
> 
> 
> Sorry Rolf, but at least on my HT processor running Windows XP pro, the 
> reporting of utilization by task manager is exactly as described by Brian.

Strange, I'm running WinXP pro, all patched up.  And if I run two CPU 
bound programs (cygwin or not) my utilization goes to 100% (easily).


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