From owner-freebsd-current Tue Nov 14 00:51:42 1995 Return-Path: owner-current Received: (from root@localhost) by freefall.freebsd.org (8.6.12/8.6.6) id AAA11520 for current-outgoing; Tue, 14 Nov 1995 00:51:42 -0800 Received: from tfs.com (tfs.com [140.145.250.1]) by freefall.freebsd.org (8.6.12/8.6.6) with SMTP id AAA11498 for ; Tue, 14 Nov 1995 00:51:32 -0800 Received: from critter.tfs.com by tfs.com (smail3.1.28.1) with SMTP id m0tFH5V-0003wQC; Tue, 14 Nov 95 00:51 PST Received: from localhost (localhost [127.0.0.1]) by critter.tfs.com (8.6.11/8.6.9) with SMTP id JAA00338; Tue, 14 Nov 1995 09:51:26 +0100 X-Authentication-Warning: localhost.tfs.com: Host localhost didn't use HELO protocol To: davidg@Root.COM cc: current@freebsd.org In-reply-to: Your message of "Tue, 14 Nov 1995 00:43:12 PST." <199511140843.AAA00206@corbin.Root.COM> Date: Tue, 14 Nov 1995 09:51:26 +0100 Message-ID: <336.816339086@critter.tfs.com> From: Poul-Henning Kamp Sender: owner-current@freebsd.org Precedence: bulk > >> "Fixing" this is very difficult and would require a rewrite of the code > >> involved. > > > >Why would this: > > > > void > > update_every_3_sec() > > { > > static int i; > > > > for all buffers { > > if ((blockno % 10) == i) > > write it > > } > > i = ++i % 10; > > } > > > >give more io traffic ? > > Because delayed write buffers are delayed for a reason. It's the > expectation that additional data/changes will be made to the buffer before > it is written out. In the case where stuff is being appended to files via > small writes (like log files, for instance), doing an update 10 times more > often may very well increase the number of writes by 10 times. I still don't follow you. Are we talking about the same thing ? The mean time between updates for any one particular buffer is still 30 seconds, so how can this change so much ? We just stage the writes instead of doing them all at the same time. Unless you can show me where we prefer buffers with a particular last decimal digit in their block-numbers then I have a hard time beliving your results... I had a patch (crude hack really) for this back in Pleasant Hill but I have no idea where to find it now, but it didn't show any adverse effects for me, quite the contrary... It cured the hangs I had, which was the kind which would be signalled by a significant rattle from the disks... -- Poul-Henning Kamp | phk@FreeBSD.ORG FreeBSD Core-team. http://www.freebsd.org/~phk | phk@login.dknet.dk Private mailbox. whois: [PHK] | phk@ref.tfs.com TRW Financial Systems, Inc. Future will arrive by its own means, progress not so.