From owner-freebsd-current Tue Nov 14 01:12:52 1995 Return-Path: owner-current Received: (from root@localhost) by freefall.freebsd.org (8.6.12/8.6.6) id BAA14242 for current-outgoing; Tue, 14 Nov 1995 01:12:52 -0800 Received: from tfs.com (tfs.com [140.145.250.1]) by freefall.freebsd.org (8.6.12/8.6.6) with SMTP id BAA14222 for ; Tue, 14 Nov 1995 01:12:42 -0800 Received: from critter.tfs.com by tfs.com (smail3.1.28.1) with SMTP id m0tFHPy-0003vkC; Tue, 14 Nov 95 01:12 PST Received: from localhost (localhost [127.0.0.1]) by critter.tfs.com (8.6.11/8.6.9) with SMTP id KAA00419; Tue, 14 Nov 1995 10:12:36 +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 01:08:06 PST." <199511140908.BAA00238@corbin.Root.COM> Date: Tue, 14 Nov 1995 10:12:35 +0100 Message-ID: <417.816340355@critter.tfs.com> From: Poul-Henning Kamp Sender: owner-current@freebsd.org Precedence: bulk > >> > 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 ? > > Perhaps not. > > >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... > > Umm, this isn't desired - you'll lose the ability to do write clustering. > The scheme I implemented did buffer aging. Hmm, that would make a difference I guess... Well, I'll make some experiemnts with it again, some time... :-) -- 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.