Date: Mon, 9 Aug 2010 22:56:10 +0000 (UTC) From: Ivan Voras <ivoras@FreeBSD.org> To: src-committers@freebsd.org, svn-src-all@freebsd.org, svn-src-head@freebsd.org Subject: svn commit: r211126 - head/sys/kern Message-ID: <201008092256.o79MuAnm031488@svn.freebsd.org>
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Author: ivoras Date: Mon Aug 9 22:56:10 2010 New Revision: 211126 URL: http://svn.freebsd.org/changeset/base/211126 Log: Bumping the read-ahead count once more, to value equivalent to 512 KiB on most system, based on benchmark results on a low-end fibre channel SAN under VMWare: vfs.read_max read performance 8 (historical default) 83 MB/s 16 (recent bump) 131 MB/s 32 (this version) 152 MB/s 64 157 MB/s (results are +/- 3 MB/s) As read-ahead is heuristic, based on past IO requests, it shouldn't be problematic. The new default is still smaller then in other OSes. Modified: head/sys/kern/vfs_cluster.c Modified: head/sys/kern/vfs_cluster.c ============================================================================== --- head/sys/kern/vfs_cluster.c Mon Aug 9 22:30:14 2010 (r211125) +++ head/sys/kern/vfs_cluster.c Mon Aug 9 22:56:10 2010 (r211126) @@ -71,7 +71,7 @@ static int write_behind = 1; SYSCTL_INT(_vfs, OID_AUTO, write_behind, CTLFLAG_RW, &write_behind, 0, "Cluster write-behind; 0: disable, 1: enable, 2: backed off"); -static int read_max = 16; +static int read_max = 32; SYSCTL_INT(_vfs, OID_AUTO, read_max, CTLFLAG_RW, &read_max, 0, "Cluster read-ahead max block count");
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