From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id ; Mon, 22 Jan 2001 18:01:05 -0500 Received: (majordomo@vger.kernel.org) by vger.kernel.org id ; Mon, 22 Jan 2001 18:00:45 -0500 Received: from pat.uio.no ([129.240.130.16]:3498 "EHLO pat.uio.no") by vger.kernel.org with ESMTP id ; Mon, 22 Jan 2001 18:00:36 -0500 MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Transfer-Encoding: 7bit Message-ID: <14956.48013.908491.509166@charged.uio.no> Date: Tue, 23 Jan 2001 00:00:29 +0100 (CET) To: "H . J . Lu" Cc: Linux Kernel , NFS maillist Subject: Re: [NFS] [CFT] Improved RPC congestion handling for 2.4.0 (and 2.2.18) In-Reply-To: <20010122143740.A31589@valinux.com> In-Reply-To: <14904.54852.334762.889784@charged.uio.no> <20010122143740.A31589@valinux.com> X-Mailer: VM 6.72 under 21.1 (patch 12) "Channel Islands" XEmacs Lucid Reply-To: trond.myklebust@fys.uio.no From: Trond Myklebust Sender: linux-kernel-owner@vger.kernel.org X-Mailing-List: linux-kernel@vger.kernel.org >>>>> " " == H J Lu writes: > I got a report which indicates it may not be a good idea, > especially for UDP. Suppose you have a lousy LAN or NFS UDP > server for whatever reason, some NFS/UDP packets may get lost > very easily while a ping request may get through. In that case, > the rpc ping may slow down the NFS client over UDP > significantly. Hi HJ, Could you clarify this? Don't forget that we only send the ping after a major timeout (usually after 3 or more resends). IOW: If the ping gets through, then it'll have cost us 1 RPC request, which is hardly a major contribution when talking about timescales of the order of 5 seconds which is what that major timeout will have cost (Don't forget that RPC timeout values increase geometrically). I'm not touting this as a cure for incorrect rsize/wsize settings. I use it rather to avoid false 'server is not responding' due to server congestion. On the current RPC code, the latter can occur sometimes even with a loopback NFS mount when, say, kflushd is busy hogging the disk... Cheers, Trond - To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org Please read the FAQ at http://www.tux.org/lkml/