linux-kernel - Re: Kernel 2.6 SMP very slow with ServerWorks LE Chipset

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Date:	Fri, 08 Dec 2006 13:34:58 +0800
From:	Bob <spam@...eurl.co.uk>
To:	linux-kernel@...r.kernel.org
Subject: Re: Kernel 2.6 SMP very slow with ServerWorks LE Chipset

Alan wrote:
>> As a test of raw CPU power I've been decompressing the kernel tree, with 
>> a UP 2.6 kernel this takes about 1m 15s, I don't know if bz2 is 
>> multithreaded but even if it's not I would expect a slight speed increase 
>> but in fact with a SMP 2.6 kernel it take 13 ~ 26m, with a SMP 2.4 
>> kernel it takes 1m 28s and with a 2.4 UP 1m 35s. 
> 
> The 2.4 numbers look correct (slightly slower), the 2.6 numbers do not.
> 
> 
> Nothing obviously wrong from the traces however. If you pin the bzip to a
> given processor do you get different results according to which CPU ?
> 
> (see man taskset for info on the commands)
> 
> If you get very different times on the two processors that will be very
> useful information.

Mmm CPU 0 in 1m 32s, but I was running things like ps and taskset in 
another terminal to verify affinity, CPU 1 still hadn't finished in 40m 
when I killed it. I've downloaded the LFDK mentioned in the other post 
and will post the results when I have them.

Thanks for replying,

This is the script I'm using to time decompression
nas:~# cat ./cputest.sh
date
taskset -c 1 nice -n -8 tar -xjf /root/linux-2.6.18.1.tar.bz2
date
uname -a
rm -r /root/linux-2.6.18.1/
nas:~#

both the tar and bzip2 processes have their affinity and priority set by 
the above command.
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