From owner-freebsd-fs Fri Nov 28 10:57:43 1997 Return-Path: Received: (from root@localhost) by hub.freebsd.org (8.8.7/8.8.7) id KAA00997 for fs-outgoing; Fri, 28 Nov 1997 10:57:43 -0800 (PST) (envelope-from owner-freebsd-fs) Received: from godzilla.zeta.org.au (godzilla.zeta.org.au [203.2.228.19]) by hub.freebsd.org (8.8.7/8.8.7) with ESMTP id KAA00991 for ; Fri, 28 Nov 1997 10:57:35 -0800 (PST) (envelope-from bde@zeta.org.au) Received: (from bde@localhost) by godzilla.zeta.org.au (8.8.7/8.6.9) id FAA10339; Sat, 29 Nov 1997 05:56:17 +1100 Date: Sat, 29 Nov 1997 05:56:17 +1100 From: Bruce Evans Message-Id: <199711281856.FAA10339@godzilla.zeta.org.au> To: bde@zeta.org.au, tlambert@primenet.com Subject: Re: ufs slowness Cc: fs@FreeBSD.ORG Sender: owner-freebsd-fs@FreeBSD.ORG X-Loop: FreeBSD.org Precedence: bulk I wrote: >ffs wants to seek a lot to switch cylinder groups (for almost every new >directory?), but I think the main problem is that it wants to seek lot >to handle fragments. I'm now making space to repartition. I'll try a >4K/4K ffs to match the ext2fs block size exactly. This was the problem. The 4K/4K ffs was about the same speed as a 4K/4K ext2fs, and a 4K/512 ffs was about as slow as an 8K/1K ffs (20+ seconds vs 40+ seconds). Some analysis of the i/o: ffs-4K-4K ffs-4K-512 contiguous blocks 7093 3481 forward seeks 450 2857 backwards seeks 258 1647 forward seeks > 64K 407 1037 backward seeks > 64K 211 797 average block size 7013 6055 The drive has an average access time 10.5 ms. Bruce