Date: Thu, 28 Feb 2002 11:43:53 -0800 From: "Frost, Stephen C" <stephen.c.frost@intel.com> To: "'freebsd-questions@freebsd.org'" <freebsd-questions@FreeBSD.ORG>, "'freebsd-hackers@freebsd.org'" <freebsd-hackers@FreeBSD.ORG>, "'freebsd-smp@freebsd.org'" <freebsd-smp@FreeBSD.ORG> Cc: "Frost, Stephen C" <stephen.c.frost@intel.com> Subject: RE: FreeBSD, SMP and Performance Speeds? Message-ID: <B9ECACBD6885D5119ADC00508B68C1EA0288A6E9@orsmsx107.jf.intel.com>
next in thread | raw e-mail | index | archive | help
I'm crossposting to freebsd-smp@freebsd.org, as per suggestion.
My original post, edited:
> > ... why any kernels compiled with SMP enabled seem
> > to be slowing the whole system down? Throughput goes down by 40%.
Tasks
> > take twice as long to run, etc, etc...
> > ... it appears to be system-wide. And is directly linked to
> > SMP: two kernels, identical EXCEPT that one has SMP enabled, the other
not.
> > The enabled kernel that *should* be fully utilizing multi-procs is
suddenly
> > effectively running at half speed.
Thanks to all for replies.
Regarding my SMP query, Doc asks:
> What sort of throughput? What sort of processes are you
> running? Do you
> actually have multiple processes fighting for CPU?
Yes, I'm using netperf, iperf or nttcp to measure TCP throughput using the
server (the box in question) in response to ten simultaneous clients.
Chariot allegedly did not show the performance hit. But then, even
measuring the process time to run a single simple script shows ~half the
speed with SMP enabled.
Chris F. asks:
> Is this an old Pentium? If so, update to a recent -stable;
> a fix was committed a few weeks ago fixing a problem where
> the caches on both processors were not enabled on Pentiums.
> Otherwise, we have a few PII and PIII boxes here that work
> quite under 4.5.
This includes multiple configurations, incl: dual PIII 700s, dual PIII 800s,
quad PIII Zeon 550s, etc... No old procs, per se. I'm running the released
version of 4.5. Was a proc-specific fix implemented *after* its release?
Greg L states:
> It would also be interesting to see if you get the same results
> running 5-CURRENT. While this version isn't suited to production use,
> it's based on a very different implementation, and the information
> would help us work out what's going on here.
Unfortunately, I do not get a whole lot of time to get experimental due to
compressed testing schedules but, if a hole opens up, I will attempt to get
some testing done using 5-CURRENT. Will report any results to you. Thanks
for your interest.
This scenario has been replicated on several (virtually any and all) test
boxes by multiple engineers. Any other tips are greatly appreciated.
TIA -
-=C. Stephen Frost=-
Intel Corp.
ICG - Network Quality Labs
Software Test Engineer
503.264.8300
All opinions are my own, not those of Intel Corporation
To Unsubscribe: send mail to majordomo@FreeBSD.org
with "unsubscribe freebsd-questions" in the body of the message
Want to link to this message? Use this URL: <https://mail-archive.FreeBSD.org/cgi/mid.cgi?B9ECACBD6885D5119ADC00508B68C1EA0288A6E9>