On Thu, Apr 28, 2011 at 08:47:38AM -0400, Pierre Lamy wrote: > Try using netblast on FreeBSD instead of iperf, there have been a lot of > discussions about this on this list. > > Is it possible you're maxing out the system's PCI-xxx bus? Did you tune > up the system buffers? Data doesn't just get queued up on the NIC > driver, it also queues within the system's kernel buffers. Try these, I > have no idea if it will help: > > sysctl -w net.inet.tcp.sendspace=373760 > sysctl -w net.inet.tcp.recvspace=373760 > sysctl -w net.local.stream.sendspace=82320 > sysctl -w net.local.stream.recvspace=82320 > sysctl -w net.local.stream.recvspace=373760 > sysctl -w net.local.stream.sendspace=373760 > sysctl -w net.raw.recvspace=373760 > sysctl -w net.raw.sendspace=373760 > sysctl -w net.inet.tcp.local_slowstart_flightsize=10 > sysctl -a net.inet.tcp.delayed_ack=0 > sysctl -w kern.maxvnodes=600000 > sysctl -w net.local.dgram.recvspace=8192 > sysctl -w net.local.dgram.maxdgram=8192 > sysctl -w net.inet.tcp.slowstart_flightsize=10 > sysctl -w net.inet.tcp.path_mtu_discovery=0 > > They're all tunable while system is running. > > -Pierre > > On 4/28/2011 3:29 AM, Adam Stylinski wrote: > > Hello, > > > > I have an intel gigabit network adapter (the 1000 GT w/chipset 82541PI) > > which performs poorly in Freebsd compared to the same card in Linux. I've > > tried this card in two different freebsd boxes and for whatever reason I > > get poor transmit performance. I've done all of the tweaking specified in > > just about every guide out there (the usual TCP window scaling, larger > > nmbclusters, delayed acks, etc) and still I get only around 600mbps. I'm > > using jumbo frames, with an MTU of 9000. I'm testing this with iperf. > > While I realize that this may not be the most realistic test, linux hosts > > with the same card can achieve 995Mbit/s to another host running this. > > When the Freebsd box is the server, Linux hosts can transmit to it at > > around 800 something Mbit/s. I've increased the transmit descriptors as > > specified in the if_em man page, and while that gave me 20 or 30 more > > mbit/s, my transmit performance is still below normal. > > > > sysctl stats report that the card is trigger a lot of tx_desc_fail2: > > dev.em.0.tx_desc_fail2: 3431 > > > > Looking at a comment in the source code this indicates that the card was > > not able to obtain enough transmit descriptors (but I've given the card the > > maximum of 4096 in my loader.conf tunable). Is this a bug or a performance > > regression of some kind? Does anybody have a fix for this? I tried > > another card with the same chip in a different box on 8-STABLE to no avail > > (the box I'm trying to improve performance on is on 8.2-RELEASE-p1). > > > > Anybody manage to make this card push above 600mbps in ideal network > > benchmarks? Any help would be gladly appreciated. > > >
I doubt I'm saturating the PCI bus, the only other thing on the bus is a really really crappy PCI video card. The same card on lesser powerful machines with Linux (Pentium 4) are able to achieve much more throughput, so it's not likely a bus limitation. I adjusted the listed sysctl live tunables which I hadn't already compensated for and it didn't seem to have an effect. -- Adam Stylinski PGP Key: http://pohl.ececs.uc.edu/~adam/publickey.pub Blog: http://technicallyliving.blogspot.com
pgptBhTUQDbpb.pgp
Description: PGP signature
