Relay-Version: version B 2.10 5/3/83; site utzoo.UUCP Posting-Version: version B 2.10.2 9/18/84; site plx.UUCP Path: utzoo!linus!philabs!cmcl2!seismo!harvard!talcott!panda!genrad!decvax!decwrl!sun!plx!jk From: jk@plx.UUCP (John Kullmann) Newsgroups: net.unix-wizards Subject: SysIII swapping strangeness Message-ID: <167@plx.UUCP> Date: Thu, 8-Aug-85 21:14:45 EDT Article-I.D.: plx.167 Posted: Thu Aug 8 21:14:45 1985 Date-Received: Mon, 12-Aug-85 02:35:50 EDT Distribution: net Organization: Plexus Computers; San Jose, CA Lines: 27 The stock swap algorithm will swap out a process which has been in memory for 2 seconds (regardless of whether it got *any* cpu time or not since it was swapped in) and swap in a selected swapped out process that has been out for at least 2 seconds. Consider a heavily memory (over)loaded system, sometimes swapping continuously for 5-20 minutes at a time. Is it possible that processes are being swapped in and back out many many times before they actually run? (some of these processes are > 500Kb). A few questions: 1) Is this 2 second business left over from the pdp11 where the address spaces were smaller? Should I/do people change this? 2) Shouldn't the swapper be changed to at least let the poor sucker get a few ticks before letting him go back out? 3) Do all un*x systems (before demand paging came around) slow way,way,way down when anything but trivial swapping is occurring? 4) Has anyone else researched this? If so, please save me some time and respond... John Kullmann ...decvax!sun!plx!jk