Messages in this thread | | | Subject | Re: hackbench regression since 2.6.25-rc | From | "Zhang, Yanmin" <> | Date | Mon, 17 Mar 2008 11:35:40 +0800 |
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On Fri, 2008-03-14 at 17:15 -0700, Christoph Lameter wrote: > Here is a patch to just not perform refills but switch slabs instead. > Could check what effect doing so has on the statistics you see on the 16p? > > --- > mm/slub.c | 5 +---- > 1 file changed, 1 insertion(+), 4 deletions(-) > > Index: linux-2.6/mm/slub.c > =================================================================== > --- linux-2.6.orig/mm/slub.c 2008-03-14 16:49:36.000000000 -0700 > +++ linux-2.6/mm/slub.c 2008-03-14 16:50:04.000000000 -0700 > @@ -1474,10 +1474,7 @@ static void *__slab_alloc(struct kmem_ca > goto new_slab; > > slab_lock(c->page); > - if (unlikely(!node_match(c, node))) > - goto another_slab; > - > - stat(c, ALLOC_REFILL); > + goto another_slab; > > load_freelist: > object = c->page->freelist; There is no much help. In 2.6.25-rc5, REFILL means refill from c->page->freelist and another_slab. It's looks like its definition is confusing. In the case of hackbench, mostly, c->page->freelist is NULL.
With #hackbench 100 process 2000, 100*20*2 (totoally 4000) processes are started. vmstat shows about 300~500 processes are at RUNNING state, so every processor runqueue has more than 20 processes running on 16p tigerton.
Below is the data with kernel 2.6.25-rc5+your_patch.
[ymzhang@lkp-tt01-x8664 ~]$ slabinfo kmalloc-512
Slabcache: kmalloc-512 Aliases: 1 Order : 0 Objects: 352
Sizes (bytes) Slabs Debug Memory ------------------------------------------------------------------------ Object : 512 Total : 56 Sanity Checks : Off Total: 229376 SlabObj: 512 Full : 36 Redzoning : Off Used : 180224 SlabSiz: 4096 Partial: 4 Poisoning : Off Loss : 49152 Loss : 0 CpuSlab: 16 Tracking : Off Lalig: 0 Align : 8 Objects: 8 Tracing : Off Lpadd: 0
kmalloc-512 has no kmem_cache operations
kmalloc-512: Kernel object allocation ----------------------------------------------------------------------- No Data
kmalloc-512: Kernel object freeing ------------------------------------------------------------------------ No Data
kmalloc-512: No NUMA information available.
Slab Perf Counter Alloc Free %Al %Fr -------------------------------------------------- Fastpath 55883575 6130576 69 7 Slowpath 24131134 73883818 30 92 Page Alloc 84844 84788 0 0 Add partial 270625 23860257 0 29 Remove partial 24046290 84752 30 0 RemoteObj/SlabFrozen 270825 439015 0 0 Total 80014709 80014394
Deactivate Full=23860293(98%) Empty=200(0%) ToHead=0(0%) ToTail=270625(1%)
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