Date: Sun, 9 Jan 2011 08:31:37 -0500 (EST) From: Rick Macklem <rmacklem@uoguelph.ca> To: Mark Saad <nonesuch@longcount.org> Cc: freebsd-hackers@freebsd.org Subject: Re: NFS Performance Message-ID: <954019999.13143.1294579897823.JavaMail.root@erie.cs.uoguelph.ca> In-Reply-To: <AANLkTin8pqdrwGZR6pB=vCnrEMm3tiGQpNsbh3RnN%2ByT@mail.gmail.com>
next in thread | previous in thread | raw e-mail | index | archive | help
> Rick > Do you have more details on the issue is it 8.x only ? Can you point > us to the stable thread abourt this ? > The bug is in the krpc, which means it's 8.x specific (at least for NFS, I'm not sure if the nlm used the krpc in 7.x?). David P. Discher reported a performance problem some time ago when testing the FreeBSD8 client against certain servers. (I can't find the thread, so maybe it never had a freebsd-stable@ cc after all.) Fortutnately John Gemignani spotted the cause (for at least his case, because he tested a patch that seemed to resolve the problem). The bug is basically that the client side krpc for TCP assumed that the 4 bytes of data that hold the length of the RPC message are in one mbuf and don't straddle multiple mbufs. If the 4 bytes does straddle multiple mbufs, the krpc gets a "garbage message length" and then typically wedges and eventually recovers by starting a fresh TCP connection up and retrying the outstanding RPCs. I have no idea if George is seeing the same problem, but the 1.5minute logjams suggest that it might. I emailed him a patch and, hopefully, he will report back on whether or not it helped. A patch for the above bug is "in the works" for head, rick
Want to link to this message? Use this URL: <https://mail-archive.FreeBSD.org/cgi/mid.cgi?954019999.13143.1294579897823.JavaMail.root>