From owner-freebsd-hackers@FreeBSD.ORG Sun Jan 9 13:31:40 2011 Return-Path: Delivered-To: freebsd-hackers@freebsd.org Received: from mx1.freebsd.org (mx1.freebsd.org [IPv6:2001:4f8:fff6::34]) by hub.freebsd.org (Postfix) with ESMTP id 06F2E106564A for ; Sun, 9 Jan 2011 13:31:40 +0000 (UTC) (envelope-from rmacklem@uoguelph.ca) Received: from esa-annu.mail.uoguelph.ca (esa-annu.mail.uoguelph.ca [131.104.91.36]) by mx1.freebsd.org (Postfix) with ESMTP id E9E4B8FC15 for ; Sun, 9 Jan 2011 13:31:38 +0000 (UTC) X-IronPort-Anti-Spam-Filtered: true X-IronPort-Anti-Spam-Result: ApwEAGNHKU2DaFvO/2dsb2JhbACEA6E3rkKMQoEhgzd0BIRnhiM X-IronPort-AV: E=Sophos;i="4.60,296,1291611600"; d="scan'208";a="104731155" Received: from erie.cs.uoguelph.ca (HELO zcs3.mail.uoguelph.ca) ([131.104.91.206]) by esa-annu-pri.mail.uoguelph.ca with ESMTP; 09 Jan 2011 08:31:37 -0500 Received: from zcs3.mail.uoguelph.ca (localhost.localdomain [127.0.0.1]) by zcs3.mail.uoguelph.ca (Postfix) with ESMTP id E33D7B40BD; Sun, 9 Jan 2011 08:31:37 -0500 (EST) Date: Sun, 9 Jan 2011 08:31:37 -0500 (EST) From: Rick Macklem To: Mark Saad Message-ID: <954019999.13143.1294579897823.JavaMail.root@erie.cs.uoguelph.ca> In-Reply-To: MIME-Version: 1.0 Content-Type: text/plain; charset=utf-8 Content-Transfer-Encoding: 7bit X-Originating-IP: [172.17.91.201] X-Mailer: Zimbra 6.0.10_GA_2692 (ZimbraWebClient - IE8 (Win)/6.0.10_GA_2692) Cc: freebsd-hackers@freebsd.org Subject: Re: NFS Performance X-BeenThere: freebsd-hackers@freebsd.org X-Mailman-Version: 2.1.5 Precedence: list List-Id: Technical Discussions relating to FreeBSD List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , X-List-Received-Date: Sun, 09 Jan 2011 13:31:40 -0000 > 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