Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S261595AbUAOU4t (ORCPT ); Thu, 15 Jan 2004 15:56:49 -0500 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S263468AbUAOU43 (ORCPT ); Thu, 15 Jan 2004 15:56:29 -0500 Received: from dh197.citi.umich.edu ([141.211.133.197]:15744 "EHLO nidelv.trondhjem.org") by vger.kernel.org with ESMTP id S261595AbUAOUy4 convert rfc822-to-8bit (ORCPT ); Thu, 15 Jan 2004 15:54:56 -0500 Subject: Re: Slowwwwwwwwwwww NFS read performance.... From: Trond Myklebust To: Ram Pai Cc: Miquel van Smoorenburg , Andrew Morton , Linus Torvalds , linux-kernel@vger.kernel.org In-Reply-To: <1074197762.1232.1.camel@nidelv.trondhjem.org> References: <200401130155.32894.hackeron@dsl.pipex.com> <1074025508.1987.10.camel@lumiere> <1074026758.4524.65.camel@nidelv.trondhjem.org> <1074134135.1522.52.camel@nidelv.trondhjem.org> <1074193256.2148.55.camel@nidelv.trondhjem.org> <1074196422.2907.35.camel@dyn319250.beaverton.ibm.com> <1074197762.1232.1.camel@nidelv.trondhjem.org> Content-Type: text/plain; charset=iso-8859-1 Content-Transfer-Encoding: 8BIT Message-Id: <1074200089.1232.6.camel@nidelv.trondhjem.org> Mime-Version: 1.0 X-Mailer: Ximian Evolution 1.4.5 Date: Thu, 15 Jan 2004 15:54:49 -0500 Sender: linux-kernel-owner@vger.kernel.org X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 1729 Lines: 40 P? to , 15/01/2004 klokka 15:16, skreiv Trond Myklebust: > P? to , 15/01/2004 klokka 14:53, skreiv Ram Pai: > > Yes this problem has been reported earlier. Attaching Andrew's patch > > that reverts a change. This should work. Please confirm. > > Sorry to disappoint you, but that change appears already in 2.6.1-mm3, > and does not suffice to fix the problem. The following reversion is what fixes my regression. That puts the sequential read numbers back to the 2.6.0 values of ~140MB/sec (from the current 2.6.1 values of 14MB/second)... Cheers, Trond diff -u --recursive --new-file linux-2.6.1-mm3/mm/readahead.c linux-2.6.1-fixed/mm/readahead.c --- linux-2.6.1-mm3/mm/readahead.c 2004-01-09 01:59:07.000000000 -0500 +++ linux-2.6.1-fixed/mm/readahead.c 2004-01-15 15:41:35.118000000 -0500 @@ -474,13 +474,9 @@ /* * This read request is within the current window. It is time * to submit I/O for the ahead window while the application is - * about to step into the ahead window. - * Heuristic: Defer reading the ahead window till we hit - * the last page in the current window. (lazy readahead) - * If we read in earlier we run the risk of wasting - * the ahead window. + * crunching through the current window. */ - if (ra->ahead_start == 0 && offset == (ra->start + ra->size -1)) { + if (ra->ahead_start == 0) { ra->ahead_start = ra->start + ra->size; ra->ahead_size = ra->next_size; actual = do_page_cache_readahead(mapping, filp, - To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/