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Path: sserve!manuel.anu.edu.au!munnari.oz.au!spool.mu.edu!uwm.edu!ogicse!news.u.washington.edu!ns1.nodak.edu!plains.NoDak.edu!tinguely From: tinguely@plains.NoDak.edu (Mark Tinguely) Newsgroups: comp.unix.bsd Subject: Re: Occasional system hangs Message-ID: <Bz495r.Byn@ns1.nodak.edu> Date: 11 Dec 92 22:29:51 GMT Article-I.D.: ns1.Bz495r.Byn References: <andrewh.724059111@bruce.cs.monash.edu.au> <1gaclpINN84v@hrd769.brooks.af.mil> <1992Dec11.210430.17335@coe.montana.edu> Sender: usenet@ns1.nodak.edu (News login) Organization: North Dakota State University Lines: 24 Nntp-Posting-Host: plains.nodak.edu Did all of you with 16+ Megs of RAM apply the patch to restrict the size of bufpages (Terry Lambert's patchkit patch #2. The calculations for bufpages were being done interchangedly in pages and bytes, the fix did not correct the calculation problem, but limited the error of the calculation; without this correction, too much RAM is lost to bufpages). Besides, there are small memory leaks in the kernel; Programs that fork a lot, cause the system to hang (make and apparently news); Big programs like X also make hanging very likely; Even a couple simple looping mallocing processes can hang a system. I agree that a kernel fix is better than a symptom avoidance technique. The kernel change is massive. The VM allows over extention of the swap backstore (and this can lead to the system freeze -- all of the swap blocks are used or fragmented to a point a certain size block cannot be allocated, new request for VM -- page a new part of a program, use of an already malloced **but memory in swap backstore is not reserved until paged out** memory, forking (only small part is new on a fork), and exec-ing a new program will look for physical memory, but cannot get it until the dirty pages are put on swap backstore, but backstore is full ... system will work the drive a little but will eventually freeze. --mark.