Messages in this thread |  | | Date | Sun, 09 Sep 2001 18:55:00 +0200 | From | Manfred Spraul <> | Subject | Re: Purpose of the mm/slab.c changes |
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Alan Cox wrote: > > > > doesn't matter which free page is used first/last. > > > > You're full of crap. > > LIFO is obviously superior due to cache re-use. > > Interersting question however. On SMP without sufficient per CPU slab caches > is tht still the case ?
Correct. SMP was perfect LIFO even without Andrea's changes.
I thought Andrea tried to reduce the fragmentation, therefore I wrote "free is free".
But even for cache re-use his changes are not a big change: The main fifo/lifo ordering on UP is mandated by the defragmentation property of the slab allocator.
Afaics there is exactly one case where my code is not lifo and Andrea's is: kmem_cache_free frees the last object in slab, each slab contains more than one object, and there are no further partial slabs. In all other cases Andrea just adds list_del();list_add() instead of changes to the firstnotfull pointer.
full->partial is/was lifo, partial->partial doesn't change the lists at all partial->empty was fifo, is now lifo_if_no_partial_slab_exists
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