Re: [PATCH] Re: MM deadlock [was: Re: arca-vm-8...]

Stephen C. Tweedie
1999-01-13T22:10:40Z

Hi,

On Wed, 13 Jan 1999 19:52:03 +0100 (CET), Andrea Arcangeli
<andrea@e-mind.com> said:

> Note that we don't need nr_async_pages at all. Here when the limit of
> nr_async_pages is low it's only a bottleneck for swapout performances. I
> have not removed it (because it could be useful to decrease swapout I/O if
> somebody needs this strange feature), but I have added a
> page_daemon.max_async_pages and set it to something like 256. Now I check
> nr_async_pages against the new max_async_pages.

The problem is that if you do this, it is easy for the swapper to
generate huge amounts of async IO without actually freeing any real
memory: there's a question of balancing the amount of free memory we
have available right now with the amount which we are in the process of
freeing. Setting the nr_async_pages bound to 256 just makes the swapper
keen to send a whole 1MB of memory out to disk at a time, which is a bit
steep on an 8MB box.

--Stephen