Re: [PATCH][RFC] slabnow

[Daniel Phillips <phillips@arcor.de>]

On Saturday 07 September 2002 16:06, Ed Tomlinson wrote:
> +	/*
> +	 * Here we assume it costs one seek to replace a lru page and that
> +	 * it also takes a seek to recreate a cache object.  With this in
> +	 * mind we age equal percentages of the lru and ageable caches.
> +	 * This should balance the seeks generated by these structures.
> +	 */

It's not a reliable assumption, for example, what is the relation between an 
skbuff and a disk seek?  Still, a better model need not be much different 
from what you've done - simply pick an arbitrary unit against which you 
estimate the average cost of replacing one unit of a given slab, and plug 
that a ratios against that into each slab header.  Make the default 
1*DISK_SEEK_COST and you will get the current behaviour, then tune the things 
that are obviously broken.

By the way, ratio multiplication is a *basic* and essential tool of any
control system worthy of the name, it's too bad Linux is so horribly
lacking in that department.  (Life without double-length intermediate
muldiv results is not worth living.)

-- 
Daniel
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