Re: [patch 3/4] slab reclaim balancing

Manfred Spraul (manfred@colorfullife.com)
Fri, 27 Sep 2002 17:59:48 +0200

Andrew Morton wrote:
>>
>>Is that actually the right approach? For large objects, it would be
>>possible to cripple the freeable slabs list, and to perform the cache
>>hit optimization (i.e. per-cpu LIFO) in page_alloc.c, but that doesn't
>>work with small objects.
>
>
> Well with a, what? 100:1 speed ratio, we'll generally get best results
> from optimising for locality/recency of reference.
>
You misunderstood me:

AFAICS slab.c has 2 weaks spots:
* cache hit rates are ignored on UP, and for objects > PAGE_SIZE on both
SMP and UP.
* freeable pages are not returned efficiently to page_alloc.c, neither
on SMP nor on UP. On SMP, this is a big problems, because the
cache_chain_semaphore is overloaded.

I just wanted to say that a hotlist in page_alloc.c is not able to
replace a hotlist in slab.c, because many objects are smaller than page
size. Both lists are needed.

--
	Manfred




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