Date: Wed, 24 Mar 1999 10:30:53 +0100 (CET) From: Konrad Heuer <kheuer@gwdu60.gwdg.de> To: Greg Black <gjb@comkey.com.au> Cc: "Scott I. Remick" <scott@computeralt.com>, FreeBSD Questions <freebsd-questions@FreeBSD.ORG> Subject: Re: Out of Swap Space hangs system Message-ID: <Pine.BSF.4.05.9903241014490.78968-100000@gwdu60.gwdg.de> In-Reply-To: <19990323211859.16523.qmail@alpha.comkey.com.au>
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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
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