RE: FreeBSD, SMP and Performance Speeds?
>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. I'm no expert but I'm going to have a shot at this anyways. Comments are welcome. =) When you run a benchmark or a process where network performance is the bottleneck instead of CPU time, you're not going to have SMP help you at all. Currently in the 4.X kernels the kernel can run on only one CPU at a given time. That means that when raw network performance is the bottleneck only one CPU is actually doing the work, and running in SMP mode gives you a lot of overhead. The same is true for a situation where a single single-threaded process is involved. A single-threaded process can only run on one CPU at a given time, so having a 2nd CPU only adds overhead. Have you tried running 4 jobs simultaneously and timing that? So what sort of application are you using exactly, is it multi-process, multithreaded, CPU intensive, network intensive? Where do you think the bottleneck in the performance lies at this moment? Doc To Unsubscribe: send mail to [EMAIL PROTECTED] with "unsubscribe freebsd-hackers" in the body of the message
Re: FreeBSD, SMP and Performance Speeds?
This is not so relevant because he is NOT RUNNING old hardware! (well not THAT old). On Thu, 28 Feb 2002, Terry Lambert wrote: > "Frost, Stephen C" wrote: > > 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? > > There is code in 4.5 that is incredibly slow on older > hardware. THis has been fixed in -current and -stable. > > Please see the list archives for the patch, if you can > not update to -stable. > > -- Terry > > To Unsubscribe: send mail to [EMAIL PROTECTED] > with "unsubscribe freebsd-smp" in the body of the message > To Unsubscribe: send mail to [EMAIL PROTECTED] with "unsubscribe freebsd-hackers" in the body of the message
Re: FreeBSD, SMP and Performance Speeds?
"Frost, Stephen C" wrote: > 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? There is code in 4.5 that is incredibly slow on older hardware. THis has been fixed in -current and -stable. Please see the list archives for the patch, if you can not update to -stable. -- Terry To Unsubscribe: send mail to [EMAIL PROTECTED] with "unsubscribe freebsd-hackers" in the body of the message
Re: FreeBSD, SMP and Performance Speeds?
* Frost, Stephen C <[EMAIL PROTECTED]> [020228 11:44] wrote: > > 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? Yes. -- -Alfred Perlstein [[EMAIL PROTECTED]] 'Instead of asking why a piece of software is using "1970s technology," start asking why software is ignoring 30 years of accumulated wisdom.' Tax deductible donations for FreeBSD: http://www.freebsdfoundation.org/ To Unsubscribe: send mail to [EMAIL PROTECTED] with "unsubscribe freebsd-hackers" in the body of the message
RE: FreeBSD, SMP and Performance Speeds?
I'm crossposting to [EMAIL PROTECTED], 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 [EMAIL PROTECTED] with "unsubscribe freebsd-hackers" in the body of the message
Re: FreeBSD, SMP and Performance Speeds?
>I have RTFM'd, with little luck. Can some enlightened soul impart knowledge >upon me, thus letting me know 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... What sort of throughput? What sort of processes are you running? Do you actually have multiple processes fighting for CPU? Doc To Unsubscribe: send mail to [EMAIL PROTECTED] with "unsubscribe freebsd-hackers" in the body of the message
Re: FreeBSD, SMP and Performance Speeds?
On Wed, Feb 27, 2002 at 04:26:35PM -0800, Frost, Stephen C wrote: > > All - > > I have RTFM'd, with little luck. Can some enlightened soul impart knowledge > upon me, thus letting me know 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... > > I have multiple boxes (Dells, IBM's, Microns, Gateways...) running FreeBSd > 4.5, all showing the same phenomenon. I initially mistook it for a NIC > driver issue, but 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. > > Is this a config issue? Any helpful hints? Or is it better just to keep > SMP disabled on a multi-proc box? > 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. (oh, you might want to try the freebsd-smp list) -- Chris D. Faulhaber - [EMAIL PROTECTED] - [EMAIL PROTECTED] FreeBSD: The Power To Serve - http://www.FreeBSD.org msg32229/pgp0.pgp Description: PGP signature
