Return to BSD News archive
Path: sserve!newshost.anu.edu.au!harbinger.cc.monash.edu.au!bunyip.cc.uq.oz.au!munnari.oz.au!sgiblab!uhog.mit.edu!MathWorks.Com!news2.near.net!news.delphi.com!usenet From: John Dyson <dysonj@delphi.com> Newsgroups: comp.os.386bsd.bugs Subject: Re: Possible Swapping bug (or design flaw?) Date: Wed, 20 Jul 94 02:56:29 -0500 Organization: Delphi (info@delphi.com email, 800-695-4005 voice) Lines: 23 Message-ID: <ZExySPt.dysonj@delphi.com> References: <5JUL199421385862@acad3.alaska.edu> <hk4RJ35.dysonj@delphi.com> <1994Jul18.125434.18703@roxi.rz.fht-mannheim.de> NNTP-Posting-Host: bos1c.delphi.com X-To: Dirk Zoller <duz@roxi.rz.fht-mannheim.de> Dirk Zoller <duz@roxi.rz.fht-mannheim.de> writes: >I regularly observe that swap runs full while I'm working. I mostly >use emacs and compilers, TeX and X of course. I don't feel I'm >stressing the system very much. (The system may be multitasking, not >so myself :-) FreeBSD V1.1.X uses swap space pretty aggressively. It actually calculates whether or not it is better to keep a page on disk, as opposed to memory. It is possible for pages to be paged out when it is counterintuitive. For example, when inactive objects (e.g. text segments) have been used repeatedly they will have higher priority than pages that are used only once in a while. The text segments can bump the less used r/w pages onto swap. Some of this algorithmic complexity has been added to support the merged VM/buffer cache. The code *really* tries to get the most %cpu usage out of your system. The cost is that swap is relied upon more heavily. Additionally -- there is very little capability in FreeBSD to run more program space than total swap space. This was changed to keep the system from hanging when the system runs out of memory+swap. Perhaps the change was too conservative, and we are looking at alternative solutions to that problem for V2.0. John dyson@implode.root.com