From owner-freebsd-questions Wed Mar 24 1:32:39 1999 Delivered-To: freebsd-questions@freebsd.org Received: from gwdu60.gwdg.de (gwdu60.gwdg.de [134.76.10.60]) by hub.freebsd.org (Postfix) with ESMTP id 2523B14C40 for ; Wed, 24 Mar 1999 01:32:32 -0800 (PST) (envelope-from kheuer@gwdu60.gwdg.de) Received: from localhost (kheuer@localhost) by gwdu60.gwdg.de (8.9.2/8.9.2) with ESMTP id KAA79000; Wed, 24 Mar 1999 10:30:53 +0100 (CET) (envelope-from kheuer@gwdu60.gwdg.de) Date: Wed, 24 Mar 1999 10:30:53 +0100 (CET) From: Konrad Heuer To: Greg Black Cc: "Scott I. Remick" , FreeBSD Questions Subject: Re: Out of Swap Space hangs system In-Reply-To: <19990323211859.16523.qmail@alpha.comkey.com.au> Message-ID: MIME-Version: 1.0 Content-Type: TEXT/PLAIN; charset=X-UNKNOWN Content-Transfer-Encoding: QUOTED-PRINTABLE Sender: owner-freebsd-questions@FreeBSD.ORG Precedence: bulk X-Loop: FreeBSD.ORG On Wed, 24 Mar 1999, Greg Black wrote: > > > Is it normal for running out of swap space to hang the system? > >=20 > > Unfortunately, yes. >=20 > Right, so far. >=20 > > It should not be, especially for a server OS. >=20 > By all means provide an algorithm to solve it, if it concerns > you. I think you'll find it's non-trivial. You're right, no doubt; it's not trivial. And the problem will not prevent me from using and recommending FreeBSD. > It's not a serious problem -- a properly setup Unix system will never > crash from lack of swap. I've been running Unix machines for the best > part of 20 years and never seen a panic from lack of swap. Some of > those machines had 0.5 MB of RAM and a single 50 MB disk, supported > several users in a commercial environment and only ever fell over when > somebody yanked the power cord. None of my FreeBSD systems crashed because of lack of swap in normal operation mode. But in principle it's easy to crash them as an unprivileged user. Just write a piece of C code which allocates m MB of memory, forks p times and writes to allocated memory in each process. Will m times p fit into the total virtual memory? Maybe, if you set rigorous per-process limits. But if you do, you might also prevent users from doing reasonable tasks. Or have I overlooked something? Regards // // Konrad Heuer ____ ___ _____= __=20 // Gesellschaft f=FCr wissenschaftliche / __/______ ___ / _ )/ __= / _ \ // Datenverarbeitung mbH G=D6ttingen / _// __/ -_) -_) _ |\ \/= // / // Am Fa=DFberg, D-37077 G=D6ttingen /_/ /_/ \__/\__/____/___= /____/=20 // Deutschland (Germany) ----- The Power to Serve ----= - // http://www.freebsd.org // kheuer@gwdu60.gwdg.de // To Unsubscribe: send mail to majordomo@FreeBSD.org with "unsubscribe freebsd-questions" in the body of the message