Date: Thu, 28 Jul 2005 09:31:43 -0700 (PDT) From: dpk <dpk@dpk.net> To: questions@freebsd.org Subject: Re: FreeBSD 5.4+SMP, severe network degredation Message-ID: <20050728093106.E79761@shared10.hosting.flyingcroc.net> In-Reply-To: <20050727185853.D23753@shared10.hosting.flyingcroc.net> References: <20050727185853.D23753@shared10.hosting.flyingcroc.net>
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By the way, I also compared GENERIC performance against GENERIC w/ "options SMP" added, and had the same results. On Wed, 27 Jul 2005, dpk wrote: > We just received several SuperMicro servers, 3.0Ghz Xeon x 2, 4GB RAM. > They're using the em driver and the ports are set to 1000Mbit (we also > tried 100Mbit/full duplex on the card and on the switch). They're running > FreeBSD 5.4. > > I ran a steady ping on a couple of them while they were running "GENERIC", > and then rebooted them with a kernel built with the "PAE" kernel included > with the installation, with "option SMP" added. > > The PAE-SMP-GENERIC kernel was built after cvsup'ing with "tag=RELENG_5_4" > and the uname reports "5.4-RELEASE-p5". > > Here are the ping results: > > GENERIC: > > 117 packets transmitted, 117 packets received, 0% packet loss > round-trip min/avg/max/stddev = 0.451/0.554/0.856/0.059 ms > > PAE-SMP-GENERIC: > > 102 packets transmitted, 102 packets received, 0% packet loss > round-trip min/avg/max/stddev = 0.569/4.262/7.944/2.065 ms > > Fetching a 637MB ISO from a local server, also on 100/FDX: > > GENERIC: > > /dev/null 100% of 637 MB 10 MBps 00m00s > > real 0m58.071s > user 0m1.954s > sys 0m6.278s > > PAE-SMP-GENERIC: > > /dev/null 100% of 637 MB 5764 kBps 00m00s > > real 1m53.324s > user 0m1.478s > sys 0m5.624s > > Running GENERIC, systat shows about 7000 interrupts/second, and around 600 > interrupts/second using PAE-SMP-GENERIC, while fetch was running. > > I've checked the errata and hardware notes, as well as gnats, and was not > able to find anything that explains or matches this behavior. We've run > SMP servers for years, using 4.5-4.11, but we've never seen the network > performance cut in half (or pings go up 10x). > > Removing "option SMP" makes the problem go away, but at a very significant > performance cost obviously. > > Could it be something from -p5? Is this explained/examined in a PR I've > missed, and if so can I add some information? >
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