Peer review of AMD64/FreeBSD article

Jem Matzan valour at thejemreport.com
Fri Mar 12 11:46:01 PST 2004


John-Mark Gurney wrote:

>Jem Matzan wrote this message on Fri, Mar 12, 2004 at 07:08 -0500:
>  
>
>>I've just finished writing this article comparing performance between an 
>>Athlon64 in 32-bit and 64-bit mode using FreeBSD:
>>
>>http://www.thejemreport.com/lab64/amd64vsi386.php
>>
>>(this is a temporary address which will later redirect to the published 
>>article)
>>    
>>
>
>A comment on the article, you mention:
>Curiously the Pentium4 times are impossible; according to the numbers for -j3 and -j4, it takes longer to execute the utility than it does to complete the entire process. This is either a bug in the time command (in relation to multithreading, perhaps), or something isn't reporting properly.
>
>You said that you enabled HyperThreading, and THIS is the reason for
>the imposible times.  Since w/ HT it appears as if there are two cpus
>and two processes are running on each of these CPU's, you end up with
>a user time that can be 2x real time.
>
>Hope this helps.
>
>  
>
Thanks -- I'll change the article to reflect that. I was hoping someone 
would shed some light on why the user time was off like that...

-Jem


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