Re: broken VM in 2.4.10-pre9

Pavel Machek
2001-09-28T20:03:11Z

Hi!

> > > > So my suggestion was to look at getting anonymous pages backed by what
> > > > amounts to a shared memory segment. In that vein. By using an extent
> > > > based data structure we can get the cost down under the current 8 bits
> > > > per page that we have for the swap counts, and make allocating swap
> > > > pages faster. And we want to cluster related swap pages anyway so
> > > > an extent based system is a natural fit.
> > >
> > > Much of this goes away if you get rid of both the swap and anonymous page
> > > special cases. Back anonymous pages with the "whoops everything I write here
> > > vanishes mysteriously" file system and swap with a swapfs
> >
> > What exactly is anonymous memory? I thought it is what you do when you
> > want to malloc(), but you want to back that up by swap, not /dev/null.
>
> Anonymous memory is memory which is not backed by a filesystem or a
> device. eg: malloc()ed memory, shmem, mmap(MAP_PRIVATE) on a file (which
> will create anonymous memory as soon as the program which did the mmap
> writes to the mapped memory (COW)), etc.

So... how can alan propose to back anonymous memory with /dev/null?
[see above] It should be backed by swap, no?
Pavel
--
I'm pavel@ucw.cz. "In my country we have almost anarchy and I don't care."
Panos Katsaloulis describing me w.r.t. patents at discuss@linmodems.org