Relay-Version: version B 2.10 5/3/83; site utzoo.UUCP Posting-Version: version B 2.10.1 6/24/83; site mmintl.UUCP Path: utzoo!linus!philabs!pwa-b!mmintl!franka From: franka@mmintl.UUCP (Frank Adams) Newsgroups: net.arch Subject: Re: Page size and the meaning of life Message-ID: <735@mmintl.UUCP> Date: Fri, 25-Oct-85 17:13:58 EST Article-I.D.: mmintl.735 Posted: Fri Oct 25 17:13:58 1985 Date-Received: Thu, 31-Oct-85 04:06:32 EST References: <926@decwrl.UUCP> <931@lll-crg.ARpA> <146@opus.UUCP> Reply-To: franka@mmintl.UUCP (Frank Adams) Organization: Multimate International, E. Hartford, CT Lines: 25 Summary: It depends on the application(s) In article <146@opus.UUCP> rcd@opus.UUCP (Dick Dunn) writes: >> Would anyone care to comment on why we need virtual memory at all >> with a 256 meg real memory being available in the near future? > >Second response: VM is a means for getting more use out of the memory >you've got. Until that 256 Mb is almost free, there's a cost tradeoff to >be considered for how much memory you put in. VM sets the "hard limit" of >a process address space independently of the actual physical memory on the >machine, so you don't have to go out and buy more memory to run a program >with a large address space--it just runs slower. (Yes, in some cases it >runs intolerably slower. If that happens, go buy more memory, obviously.) What leads either of you to believe that 256M will be enough to run your programs? Memory used by programs expands to use the space available. There was a time, not so long ago, when 256K was a lot of memory, and people didn't understand how any program could use more than 16M. If memory becomes sufficiently cheap, there are time/space tradeoffs which can be made to use large blocks of it. Or, for a second response, if memory becomes cheap enough, what do you need *disks* for? You will need a hardware solution to preserve memory in the event of system/power crashes, of course. Frank Adams ihpn4!philabs!pwa-b!mmintl!franka Multimate International 52 Oakland Ave North E. Hartford, CT 06108