From owner-cvs-all@FreeBSD.ORG Fri Mar 12 18:56:29 2004 Return-Path: Delivered-To: cvs-all@freebsd.org Received: from mx1.FreeBSD.org (mx1.freebsd.org [216.136.204.125]) by hub.freebsd.org (Postfix) with ESMTP id 679BE16A4CE; Fri, 12 Mar 2004 18:56:29 -0800 (PST) Received: from repoman.freebsd.org (repoman.freebsd.org [216.136.204.115]) by mx1.FreeBSD.org (Postfix) with ESMTP id 5C20E43D31; Fri, 12 Mar 2004 18:56:29 -0800 (PST) (envelope-from bde@FreeBSD.org) Received: from repoman.freebsd.org (localhost [127.0.0.1]) by repoman.freebsd.org (8.12.10/8.12.10) with ESMTP id i2D2uSGe072947; Fri, 12 Mar 2004 18:56:28 -0800 (PST) (envelope-from bde@repoman.freebsd.org) Received: (from bde@localhost) by repoman.freebsd.org (8.12.10/8.12.10/Submit) id i2D2uSUu072946; Fri, 12 Mar 2004 18:56:28 -0800 (PST) (envelope-from bde) Message-Id: <200403130256.i2D2uSUu072946@repoman.freebsd.org> From: Bruce Evans Date: Fri, 12 Mar 2004 18:56:28 -0800 (PST) To: src-committers@FreeBSD.org, cvs-src@FreeBSD.org, cvs-all@FreeBSD.org X-FreeBSD-CVS-Branch: HEAD Subject: cvs commit: src/sys/kern vfs_vnops.c X-BeenThere: cvs-all@freebsd.org X-Mailman-Version: 2.1.1 Precedence: list List-Id: CVS commit messages for the entire tree List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , X-List-Received-Date: Sat, 13 Mar 2004 02:56:29 -0000 bde 2004/03/12 18:56:28 PST FreeBSD src repository Modified files: sys/kern vfs_vnops.c Log: Align the offset in vn_rdwr_inchunks() so that at most the first and the last chunk are misaligned relative to a MAXBSIZE byte boundary. vn_rdwr_inchunks() is used mainly for elf core dumps, and elf sections are usually perfectly misaligned relative to MAXBSIZE, and chunking prevents the file system from doing much realigning. This gives a surprisingly large speedup for core dumps -- from 50 to 13 seconds for a 512MB core dump here. The pessimization was mostly from an interaction of the misalignment with IO_DIRECT. It increased the number of i/o's for each chunk by a factor of 5 (3 writes and 2 read-before-writes instead of 1 write). Revision Changes Path 1.197 +11 -1 src/sys/kern/vfs_vnops.c