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SubjectRe: No, really, stop trying to delete slab until you've finished making slub perform as well
KOSAKI Motohiro wrote:


> <SLUB>
>
> % cat /proc/meminfo
>
> Slab: 1591680 kB
> SReclaimable: 12608 kB
> SUnreclaim: 1579072 kB

Unreclaimable grew very big.


> :t-0000128 28739 128 1.3G 20984/20984/8 512 0 99 0 *

Argh. Most slabs contain a single object. Probably due to the conflict resolution.


> kmalloc-192 4609 192 85.9M 1303/1303/8 341 0 99 1

And a similar but not so severe issue here.

The obvious fix is to avoid allocating another slab on conflict but how will
this impact performance?


Index: linux-2.6/mm/slub.c
===================================================================
--- linux-2.6.orig/mm/slub.c 2008-08-13 08:06:00.000000000 -0500
+++ linux-2.6/mm/slub.c 2008-08-13 08:07:59.000000000 -0500
@@ -1253,13 +1253,11 @@
static inline int lock_and_freeze_slab(struct kmem_cache_node *n,
struct page *page)
{
- if (slab_trylock(page)) {
- list_del(&page->lru);
- n->nr_partial--;
- __SetPageSlubFrozen(page);
- return 1;
- }
- return 0;
+ slab_lock(page);
+ list_del(&page->lru);
+ n->nr_partial--;
+ __SetPageSlubFrozen(page);
+ return 1;
}


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