Re: [9fans] Virtual memory in BSD and Plan9

["Thomas Bushnell, BSG" <tb+usenet@becket.net>]

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