From owner-freebsd-hackers Wed Feb 17 11:31:46 1999 Delivered-To: freebsd-hackers@freebsd.org Received: from iquest3.iquest.net (iquest3.iquest.net [209.43.20.203]) by hub.freebsd.org (Postfix) with SMTP id AFC8A115B0 for ; Wed, 17 Feb 1999 11:31:31 -0800 (PST) (envelope-from toor@y.dyson.net) Received: (qmail 14966 invoked from network); 17 Feb 1999 19:31:29 -0000 Received: from dyson.iquest.net (HELO y.dyson.net) (198.70.144.127) by iquest3.iquest.net with SMTP; 17 Feb 1999 19:31:29 -0000 Received: (from root@localhost) by y.dyson.net (8.9.1/8.9.1) id OAA69956; Wed, 17 Feb 1999 14:31:28 -0500 (EST) Message-Id: <199902171931.OAA69956@y.dyson.net> Subject: Re: savecore before swapon? In-Reply-To: <19990217142628.F69668@bitbox.follo.net> from Eivind Eklund at "Feb 17, 99 02:26:28 pm" To: eivind@FreeBSD.ORG (Eivind Eklund) Date: Wed, 17 Feb 1999 14:31:28 -0500 (EST) Cc: brandon@roguetrader.com, freebsd-hackers@FreeBSD.ORG From: "John S. Dyson" Reply-To: dyson@iquest.net X-Mailer: ELM [version 2.4ME+ PL38 (25)] MIME-Version: 1.0 Content-Type: text/plain; charset=US-ASCII Content-Transfer-Encoding: 7bit Sender: owner-freebsd-hackers@FreeBSD.ORG Precedence: bulk X-Loop: FreeBSD.ORG Eivind Eklund said: > On Tue, Feb 16, 1999 at 08:26:00AM -0700, Brandon Gillespie wrote: > > I havn't checked the source, but from my understanding shouldn't > > savecore be run before swapon is run, incase the swap device is the > > dump device? Or to look at it another way, when swapon is run on a > > swap device, does it look first to see if there is a dump in it, and > > if so what does it do? Right now we run swapon, then considerably > > later we run savecore. Assuming swapon just trashes whatever was in > > that device, running savecore is pretty much irrelevant, as most > > people I know (not necessarily in FreeBSD) use their swap device as a > > dump point. > > This is done intentionally, as fsck may in some cases require swap > to be able to fsck large filesystems. > > It would make sense to have a sysctl > 'only_swap_as_absolutely_last_resort_not_for_performance' AKA > 'do_linux_swapping_scheme' which was set before the swapon, and unset > after the crashdump. I don't know how to implement this. (It might > be that one of the present sysctls does something like this - I've not > checked). > sysctl -w vm.defer_swapspace_pageouts=1 It will still page nicely, but performance will be less when under memory load, because of less memory being available. -- John | Never try to teach a pig to sing, dyson@iquest.net | it makes one look stupid jdyson@nc.com | and it irritates the pig. To Unsubscribe: send mail to majordomo@FreeBSD.org with "unsubscribe freebsd-hackers" in the body of the message