From owner-freebsd-current Thu Mar 30 17:43:40 2000 Delivered-To: freebsd-current@freebsd.org Received: from apollo.backplane.com (apollo.backplane.com [216.240.41.2]) by hub.freebsd.org (Postfix) with ESMTP id 6B13837C2D0; Thu, 30 Mar 2000 17:43:13 -0800 (PST) (envelope-from dillon@apollo.backplane.com) Received: (from dillon@localhost) by apollo.backplane.com (8.9.3/8.9.1) id RAA71466; Thu, 30 Mar 2000 17:43:07 -0800 (PST) (envelope-from dillon) Date: Thu, 30 Mar 2000 17:43:07 -0800 (PST) From: Matthew Dillon Message-Id: <200003310143.RAA71466@apollo.backplane.com> To: Warner Losh Cc: "David O'Brien" , freebsd-current@FreeBSD.ORG Subject: Re: SMP buildworld times / performance tests References: <20000330180402.E10480@futuresouth.com> <200003300604.WAA68031@apollo.backplane.com> <20000330174453.D10480@futuresouth.com> <20000330160043.A57508@dragon.nuxi.com> <200003310058.RAA30753@harmony.village.org> Sender: owner-freebsd-current@FreeBSD.ORG Precedence: bulk X-Loop: FreeBSD.ORG :In message <20000330180402.E10480@futuresouth.com> "Matthew D. Fuller" writes: :: The question at task is, is buildworld one of them? I don't think that :: situation comes up a lot in buildworld, but I'm not exactly an authority :: on it... : :About 6 months ago, softupdates made things about 5% faster than async :for makeworld on my PPro 200 + 196M of memory. : :Warner Softupdates is basically going to beat async on just about everything, and beat it *badly* for a bunch of things like /tmp operation. There are a few minor issues with the write-behind code (e.g. that thread on DBM ops and certain contrived random I/O tests being slow), which async is much faster on, but that's just a quirk in the clustering code. I'm working on a patch set which extends the sequential read heuristic to also handle writes. The patch is currently under review and can hopefully be committed to 4.x and 5.x soon (or something like it). Async should not be used unless you really like restoring crashed filesystems from tape :-). Oh, and perhaps when one is doing an initial OS install from CDRom :-). Async itself will not cause a crash, but if your machine crashes in the middle of a bunch of async writes you might end up with an unrecoverable filesystem. Also, async can be awefully hard on the VM system if you are doing a lot of writing - there's a reason why we have write-behind code, even if it has a few bogus cases. -Matt Matthew Dillon To Unsubscribe: send mail to majordomo@FreeBSD.org with "unsubscribe freebsd-current" in the body of the message