Date: Sun, 9 Feb 2014 18:03:21 +0000 (UTC) From: naddy@mips.inka.de (Christian Weisgerber) To: freebsd-net@freebsd.org Subject: Re: Terrible NFS performance under 9.2-RELEASE? Message-ID: <ld8ft9$25o0$1@lorvorc.mips.inka.de> References: <52DC1241.7010004@egr.msu.edu> <1629593139.16590858.1390789014324.JavaMail.root@uoguelph.ca>
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Rick Macklem <rmacklem@uoguelph.ca> wrote: > I have a "hunch" that might explain why 64K NFS reads/writes perform > poorly for some network environments. > A 64K NFS read reply/write request consists of a list of 34 mbufs when > passed to TCP via sosend() and a total data length of around 65680bytes. > Looking at a couple of drivers (virtio and ixgbe), they seem to expect > no more than 32-33 mbufs in a list for a 65535 byte TSO xmit. I think > (I don't have anything that does TSO to confirm this) that NFS will pass > a list that is longer (34 plus a TCP/IP header). This may or may not be the same problem: When I switched my desktop box from FreeBSD 7 to 9, NFS read performance from my media server (running OpenBSD) became extremely poor. I couldn't even stream a movie any longer. Disabling TSO on the nfe(4) interface had no effect. My workaround was to switch from a TCP mount to a UDP one. The problem has persisted to FreeBSD 10. I can now report that switching to [rw]size=32768 with a TCP mount also works fine. -- Christian "naddy" Weisgerber naddy@mips.inka.de
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