From mboxrd@z Thu Jan 1 00:00:00 1970 To: 9fans@cse.psu.edu From: "Thomas Bushnell, BSG" Message-ID: <87pu71x2lm.fsf@becket.becket.net> Content-Type: text/plain; charset=us-ascii References: <20011029123819.DCCD7199E4@mail.cse.psu.edu> Subject: Re: [9fans] Virtual memory in BSD and Plan9 Date: Fri, 2 Nov 2001 09:58:48 +0000 Topicbox-Message-UUID: 128cdf5e-eaca-11e9-9e20-41e7f4b1d025 rob@plan9.bell-labs.com (rob pike) writes: > I'm a radical here, but I think if a machine is paging, you've lost. Many times I have been grateful that I could perform a task thanks to the availability of paging. Certainly, paging is not a substitute for having more memory. But it is reasonable to want it as a technique. Indeed, once years and years ago we had a horrid intractible kernel debugging problem on BSD, when I worked for UNM, and we solved the problem (I kid you not) by firing up emacs on /dev/mem, from which I was able to find the problem when adb was not helpful. Obviously, this strategy only worked because the system was able to page. If emacs buffers were limited to the size of memory, it would not be possible to edit /dev/mem. More prosaically, many times I have had some extensive data set to operate on in a tool that needed to keep it all in "core", and while it took much longer with paging than if I had more memory--it would take forever (literally) if the kernel didn't support paging at all. Thomas