From: Trond Myklebust Subject: Re: [PATCH] Timeouts gone wild on ia64 Date: Thu, 15 May 2003 16:31:00 +0200 Sender: nfs-admin@lists.sourceforge.net Message-ID: <16067.42148.524146.39488@charged.uio.no> References: <482A3FA0050D21419C269D13989C6113127DC8@lavender-fe.eng.netapp.com> <3EC39FDF.60609@RedHat.com> Reply-To: trond.myklebust@fys.uio.no Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii Cc: "Lever, Charles" , Trond Myklebust , nfs@lists.sourceforge.net Return-path: Received: from pat.uio.no ([129.240.130.16]) by sc8-sf-list1.sourceforge.net with esmtp (Exim 3.31-VA-mm2 #1 (Debian)) id 19GJmY-0008El-00 for ; Thu, 15 May 2003 07:32:30 -0700 To: Steve Dickson In-Reply-To: <3EC39FDF.60609@RedHat.com> Errors-To: nfs-admin@lists.sourceforge.net List-Help: List-Post: List-Subscribe: , List-Id: Discussion of NFS under Linux development, interoperability, and testing. List-Unsubscribe: , List-Archive: >>>>> " " == Steve Dickson writes: > It appears the RTO code does seem to be working but when the > minimums start so low (like at 4m instead 40ms) it takes some > time for the timeout value to build up and with soft mounts > there is no time... > Maybe I'm missing something... increasing the timeout value > should not have any affect on performance since in a well tuned > client and server these timeout will never occur since the > responses from the server will be returned before the timeout > expires... right? Also decreasing the number of timeouts will > decrease the number of retransmits which is another good > thing... True? With a properly implemented algorithm, the number of retransmits should be small anyway as it is supposed to take into account the variance on the estimated RTO. We don't want any extra artificial limits if we can avoid it. You may well be right in asserting that we're setting the initial RTO estimate too low, but then the answer should be to increase the value of the 'timeo' mount parameter as that is what defines the initial estimate. The default value of 'retrans' should also be looked at. I'm not at all comfortable with a default retrans value of '3' when doing soft mounts. At the moment I believe that the default values for these 2 parameters differ in the kernel from those in the 'mount' program. IMHO, the mount program is overriding the kernel with too low values. It would be better if 'mount' did not set timeo/retrans (unless the user overrides) and left that to the kernel. Cheers, Trond ------------------------------------------------------- Enterprise Linux Forum Conference & Expo, June 4-6, 2003, Santa Clara The only event dedicated to issues related to Linux enterprise solutions www.enterpriselinuxforum.com _______________________________________________ NFS maillist - NFS@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/nfs