Re: [PATCH 1/3] slub: set a criteria for slub node partial adding

[Eric Dumazet <eric.dumazet@gmail.com>]

Le vendredi 02 dA(C)cembre 2011 A  16:23 +0800, Alex Shi a A(C)crit :
> From: Alex Shi <alexs@intel.com>
> 
> Times performance regression were due to slub add to node partial head
> or tail. That inspired me to do tunning on the node partial adding, to
> set a criteria for head or tail position selection when do partial
> adding.
> My experiment show, when used objects is less than 1/4 total objects
> of slub performance will get about 1.5% improvement on netperf loopback
> testing with 2048 clients, wherever on our 4 or 2 sockets platforms,
> includes sandbridge or core2.
> 
> Signed-off-by: Alex Shi <alex.shi@intel.com>
> ---
>  mm/slub.c |   18 ++++++++----------
>  1 files changed, 8 insertions(+), 10 deletions(-)
> 

netperf (loopback or ethernet) is a known stress test for slub, and your
patch removes code that might hurt netperf, but benefit real workload.

Have you tried instead this far less intrusive solution ?

if (tail == DEACTIVATE_TO_TAIL ||
    page->inuse > page->objects / 4)
         list_add_tail(&page->lru, &n->partial);
else
         list_add(&page->lru, &n->partial);



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