Date: Thu, 28 Apr 2011 09:04:24 -0400 From: Mike Tancsa <mike@sentex.net> To: Adam Stylinski <kungfujesus06@gmail.com> Cc: freebsd-net@freebsd.org Subject: Re: em0 performance subpar Message-ID: <4DB965D8.7090906@sentex.net> In-Reply-To: <20110428072946.GA11391@zephyr.adamsnet> References: <20110428072946.GA11391@zephyr.adamsnet>
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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 Try the tests using the tools in /usr/src/tools/tools/netperf to generate / test udp traffic. Perhaps give the driver from HEAD a try. There are a few fixes to it. I back ported it to RELENG_8, but it should work on 8.2R as well. http://www.tancsa.com/em-723.tgz what does pciconf -lvc for your em NIC show ? also, vmstat -i ---Mike -- ------------------- Mike Tancsa, tel +1 519 651 3400 Sentex Communications, mike@sentex.net Providing Internet services since 1994 www.sentex.net Cambridge, Ontario Canada http://www.tancsa.com/
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