From: Bogdan Costescu Subject: Re: [PATCH 2.6.3] Add write throttling to NFS client Date: Thu, 26 Feb 2004 17:24:58 +0100 (CET) Sender: nfs-admin@lists.sourceforge.net Message-ID: References: <20040226145051.GE32597@suse.de> Mime-Version: 1.0 Content-Type: TEXT/PLAIN; charset=US-ASCII Cc: trond.myklebust@fys.uio.no, Greg Banks , ShantanuGoel , Return-path: Received: from sc8-sf-mx1-b.sourceforge.net ([10.3.1.11] helo=sc8-sf-mx1.sourceforge.net) by sc8-sf-list2.sourceforge.net with esmtp (Exim 4.30) id 1AwOLl-000853-3s for nfs@lists.sourceforge.net; Thu, 26 Feb 2004 08:27:01 -0800 Received: from relay.uni-heidelberg.de ([129.206.100.212]) by sc8-sf-mx1.sourceforge.net with esmtp (Exim 4.30) id 1AwOJr-0004be-3S for nfs@lists.sourceforge.net; Thu, 26 Feb 2004 08:25:03 -0800 To: Olaf Kirch In-Reply-To: <20040226145051.GE32597@suse.de> Errors-To: nfs-admin@lists.sourceforge.net List-Unsubscribe: , List-Id: Discussion of NFS under Linux development, interoperability, and testing. List-Post: List-Help: List-Subscribe: , List-Archive: On Thu, 26 Feb 2004, Olaf Kirch wrote: > The general "unfairness" observed in writes is due to the fact that we > allow a writing process to dirty a large number of pages without blocking > for the actual IO. Yes, and I think that this is pretty similar to the situation encountered with block IO, where queued writes had to be serviced before later queued reads, giving an impression of unresponsivness. It's easier to accept a delayed write than a delayed read. > Applications doing lots of stats etc are punished so severely because > all these operations are synchronous. That's exactly the case for block IO reads. > BTW I think reading is much less of a problem. The number of readaheads > scheduled by generic_file_read is limited, On the other hand, based on the block IO experience, reads should have higher priority than writes :-) -- Bogdan Costescu IWR - Interdisziplinaeres Zentrum fuer Wissenschaftliches Rechnen Universitaet Heidelberg, INF 368, D-69120 Heidelberg, GERMANY Telephone: +49 6221 54 8869, Telefax: +49 6221 54 8868 E-mail: Bogdan.Costescu@IWR.Uni-Heidelberg.De ------------------------------------------------------- SF.Net is sponsored by: Speed Start Your Linux Apps Now. Build and deploy apps & Web services for Linux with a free DVD software kit from IBM. Click Now! http://ads.osdn.com/?ad_id=1356&alloc_id=3438&op=click _______________________________________________ NFS maillist - NFS@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/nfs