Date: Fri, 30 Nov 2007 09:19:21 -0500 From: Mike Tancsa <mike@sentex.net> To: Pete French <petefrench@ticketswitch.com>, kris@freebsd.org Cc: freebsd-stable@freebsd.org Subject: Re: Also seeing 2 x quad-core system slower that 2 x dual core Message-ID: <200711301421.lAUELKx0097603@lava.sentex.ca> In-Reply-To: <E1Iy4hJ-000213-5W@dilbert.ticketswitch.com> References: <474FD17D.7080209@FreeBSD.org> <E1Iy4hJ-000213-5W@dilbert.ticketswitch.com>
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At 07:10 AM 11/30/2007, Pete French wrote:
> > Check dmesg for the APIC numbers corresponding to the CPUs you want to
> > disable and add the corresponding entries to /boot/loader.conf, e.g.:
>
>O.K., I did that, got it running on 4 CPU's only, and the problem
>is still there - so it's not the number of CPU's after all. Which
>is good in a way in that it is not completely defeating common sense,
>but means I shall go and look elsewhere for the problem.
This sort of comparison is difficult as the disk layout can be
different from machine to machine. Perhaps if you dedicate a drive
(e.g ad8) to the test and do something like
newfs -U -O2 /dev/ad8
mount /dev/ad8 /mnt
sh /tmp/script-to-create-gig-of-files-on-mnt
shutdown -r now
mount /dev/ad8 /mnt
time rm -R /mnt/testfiles
and then repeat varying the number of CPUs,
You should be able to get a rough sense of the impact of more CPUs if
there is one.
---Mike
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