Re: broken VM in 2.4.10-pre9

Rik van Riel
2001-09-21T14:23:41Z

On Fri, 21 Sep 2001, Bill Davidsen wrote:

> The list is an okay way to determine rank within a class, but I still
> think that there is a need for some balance between text, program data,
> pages loaded via i/o, perhaps more. My disquiet with the new
> implementation is based on a desire to avoid swapping program data to make
> room for i/o data (using those terms in a loose way for identification).

Preference for evicting one kind of cache is indeed a bad
thing. It might work for 90% of the workloads, but you can
be sure it breaks horribly for the other 10%.

I'm currently busy tweaking the old 2.4 VM (in the -ac kernels)
to try and get optimal performance from that one, without giving
preference to one kind of cache ... except in the situation where
the amount of cache is excessive.

> I would also like to have time to investigate what happens if the pages
> associated with a program load are handled in larger blocks, meta-pages
> perhaps, which would at least cause many to be loaded at once on a page
> fault, rather than faulting them in one at a time.

This is an interesting thing, too. Something to look into for
2.5 and if it turns out simple enough we may even want to
backport it to 2.4.

regards,

Rik
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