Dave Daniels
07-08-2003, 08:41 AM
In article <20030706170633.5f56cbf9.spyro@f2s.com>,
Ian Molton <spyro@f2s.com> wrote: ont confuse the issue with what happens when an app runs away and eats more RAM than you have on a system with VM - its common for pre-emptive OSes to have VM too.
I would say that operating systems that use pre-emptive scheduling
and virtual memory are a match made in heaven. When you hit a page
fault because of a reference to a page not in memory, you simply
dispatch someone else whilst waiting for the page to be brought it
from disk. Back in the 1970s it was the magical ingredient that
allowed dozens of users to have hundred of kilobytes of memory each
on a machine with maybe a megabyte of real memory. This was the
real power of virtual memory. I wonder if people really appreciate
that today.
Dave Daniels
Ian Molton <spyro@f2s.com> wrote: ont confuse the issue with what happens when an app runs away and eats more RAM than you have on a system with VM - its common for pre-emptive OSes to have VM too.
I would say that operating systems that use pre-emptive scheduling
and virtual memory are a match made in heaven. When you hit a page
fault because of a reference to a page not in memory, you simply
dispatch someone else whilst waiting for the page to be brought it
from disk. Back in the 1970s it was the magical ingredient that
allowed dozens of users to have hundred of kilobytes of memory each
on a machine with maybe a megabyte of real memory. This was the
real power of virtual memory. I wonder if people really appreciate
that today.
Dave Daniels