lkml.org 
[lkml]   [2001]   [Sep]   [9]   [last100]   RSS Feed
Views: [wrap][no wrap]   [headers]  [forward] 
 
Messages in this thread
    /
    Date
    From
    SubjectRe: Purpose of the mm/slab.c changes
    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

    --
    Manfred
    -
    To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
    the body of a message to majordomo@vger.kernel.org
    More majordomo info at http://vger.kernel.org/majordomo-info.html
    Please read the FAQ at http://www.tux.org/lkml/

    \
     
     \ /
      Last update: 2005-03-22 13:03    [W:0.024 / U:117.300 seconds]
    ©2003-2016 Jasper Spaans. hosted at Digital OceanAdvertise on this site