Date: Thu, 28 Apr 2011 03:29:46 -0400 From: Adam Stylinski <kungfujesus06@gmail.com> To: freebsd-net@freebsd.org Subject: em0 performance subpar Message-ID: <20110428072946.GA11391@zephyr.adamsnet>
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--qDbXVdCdHGoSgWSk Content-Type: text/plain; charset=us-ascii Content-Disposition: inline Content-Transfer-Encoding: quoted-printable Hello, I have an intel gigabit network adapter (the 1000 GT w/chipset 82541PI) whi= ch performs poorly in Freebsd compared to the same card in Linux. I've tri= ed this card in two different freebsd boxes and for whatever reason I get p= oor transmit performance. I've done all of the tweaking specified in just = about every guide out there (the usual TCP window scaling, larger nmbcluste= rs, delayed acks, etc) and still I get only around 600mbps. I'm using jumb= o frames, with an MTU of 9000. I'm testing this with iperf. While I reali= ze 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 M= bit/s. I've increased the transmit descriptors as specified in the if_em m= an page, and while that gave me 20 or 30 more mbit/s, my transmit performan= ce is still below normal. =20 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 no= t able to obtain enough transmit descriptors (but I've given the card the m= aximum 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 anothe= r card with the same chip in a different box on 8-STABLE to no avail (the b= ox 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 benchm= arks? Any help would be gladly appreciated. --=20 Adam Stylinski PGP Key: http://pohl.ececs.uc.edu/~adam/publickey.pub Blog: http://technicallyliving.blogspot.com --qDbXVdCdHGoSgWSk Content-Type: application/pgp-signature -----BEGIN PGP SIGNATURE----- Version: GnuPG v1.4.11 (FreeBSD) iQIcBAEBAgAGBQJNuRdpAAoJED6sRHE6TvmnhSwP/RncWw07PGrukndXs+/VVDLa SBPC8V1GUUW3zoisNEKORYQQ4qYM97Ql94zNB11tFR9MxjcmqJjZv2GqmVSiMGHR 5px/UOuoQjiGYxcFfqVyaN6EhaZaSGLmiYlVfNdSAFYwZ1jNcl1AsmD+zKgl6BRw UfmVui8UlmmakggQJ2qir2yr+6cmi6VV6MCaJNelHnVJ7ggHB85Qha1UdaoFqb2e UzDsAMnU6RDeEhQxvRvlv+ch0cAciTnVm/ipmR+5PQEJ4Wht4rhjTEodK/IZ8O/Z fEYapcS11HTZal6T4FMjImB3bf0YpT2tV//H5SycGDsGUNgNysbOBnuP/rway7x0 Qhp5XR1gKW7YNCzREe9dK7QtmUIcjHIFw9/qSWt4tRaEerpDR8sH9JUq71Hvc2QC pws9SHFBzYjV4zKZg597TJuuSY0gWPKpRZmPmY3mZ0aR0LnbVQgO29ay0lgCuyxF owhdUUb5JKmn9H7vcOacTQYYP//GyWMMYnVMmDCecz5jOWAQuN5xx4htQKhDu1I5 bV3qG1+j2F6iIEP+7DKWogIEF3QcbF3vecboeehc5MouoIpEyLm6jyA3GQnW/gE4 RNuqKVuoMFgqK06QdBNNgysNkfj3oY4WrkDPoNAJFvE2PYeIZxFzr7Cve5Cm+Bgt 8lL3b3dFM7OkIzx5CUAh =hke5 -----END PGP SIGNATURE----- --qDbXVdCdHGoSgWSk--
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