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From: Manfred Spraul <manfred@colorfullife.com>
To: Andrew Morton <akpm@digeo.com>
Cc: Ed Tomlinson <tomlins@cam.org>, linux-kernel@vger.kernel.org
Subject: Re: [patch 3/4] slab reclaim balancing
Date: Fri, 27 Sep 2002 17:59:48 +0200	[thread overview]
Message-ID: <3D948074.5030800@colorfullife.com> (raw)
In-Reply-To: 3D937E87.D387F358@digeo.com

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



  parent reply	other threads:[~2002-09-27 15:54 UTC|newest]

Thread overview: 17+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2002-09-26 14:13 [patch 3/4] slab reclaim balancing Manfred Spraul
2002-09-26 14:20 ` William Lee Irwin III
2002-09-26 15:24   ` Manfred Spraul
2002-09-26 17:37 ` Andrew Morton
2002-09-26 18:47   ` Manfred Spraul
2002-09-26 19:49     ` Andrew Morton
2002-09-26 20:49       ` Manfred Spraul
2002-09-26 21:39         ` Andrew Morton
2002-09-27  0:41           ` Ed Tomlinson
2002-09-27 17:24             ` Manfred Spraul
2002-09-27 18:26               ` Andrew Morton
2002-09-27 19:38                 ` Manfred Spraul
2002-09-27 19:52                   ` Andrew Morton
2002-09-27 15:59           ` Manfred Spraul [this message]
  -- strict thread matches above, loose matches on Subject: below --
2002-09-26  4:08 Andrew Morton
2002-09-26 11:39 ` Ed Tomlinson
2002-09-26 15:09 ` Ed Tomlinson

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