Thread (2 messages) 2 messages, 2 authors, 2001-09-26

Re: broken VM in 2.4.10-pre9

From: Marcelo Tosatti <hidden>
Date: 2001-09-26 19:45:42
Also in: lkml

On Tue, 25 Sep 2001, Pavel Machek wrote:
Hi!
quoted
quoted
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.

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