On Tue, Jan 26, 2016 at 08:40:13PM -0800, Andrew Morton wrote: > On Thu, 14 Jan 2016 14:24:13 +0900 Joonsoo Kim <js1304@xxxxxxxxx> wrote: > > > This patchset implements new freed object management way, that is, > > OBJFREELIST_SLAB. Purpose of it is to reduce memory overhead in SLAB. > > > > SLAB needs a array to manage freed objects in a slab. If there is > > leftover after objects are packed into a slab, we can use it as > > a management array, and, in this case, there is no memory waste. > > But, in the other cases, we need to allocate extra memory for > > a management array or utilize dedicated internal memory in a slab for it. > > Both cases causes memory waste so it's not good. > > > > With this patchset, freed object itself can be used for a management > > array. So, memory waste could be reduced. Detailed idea and numbers > > are described in last patch's commit description. Please refer it. > > > > In fact, I tested another idea implementing OBJFREELIST_SLAB with > > extendable linked array through another freed object. It can remove > > memory waste completely but it causes more computational overhead > > in critical lock path and it seems that overhead outweigh benefit. > > So, this patchset doesn't include it. I will attach prototype just for > > a reference. > > It appears that this patchset is perhaps due a couple of touchups from > Christoph's comments. I'll grab it as-is as I want to get an mmotm > into linux-next tomorrow then vanish for a few days. Hello, Andrew. Could you add just one small fix below to 16/16 "mm/slab: introduce new slab management type, OBJFREELIST_SLAB"? Thanks. ------------>8------------- >From f2afad62904fe3129c1a296987954076fb8f6b5a Mon Sep 17 00:00:00 2001 From: Joonsoo Kim <iamjoonsoo.kim@xxxxxxx> Date: Wed, 27 Jan 2016 10:36:05 +0900 Subject: [PATCH] fix SLAB_DESTROTY_BY_RCU --- mm/slab.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) diff --git a/mm/slab.c b/mm/slab.c index 56777a7..ee44d78 100644 --- a/mm/slab.c +++ b/mm/slab.c @@ -2019,7 +2019,7 @@ static bool set_objfreelist_slab_cache(struct kmem_cache *cachep, cachep->num = 0; - if (cachep->ctor) + if (cachep->ctor || flags & SLAB_DESTROY_BY_RCU) return false; left = calculate_slab_order(cachep, size, -- 1.9.1 -- To unsubscribe, send a message with 'unsubscribe linux-mm' in the body to majordomo@xxxxxxxxx. For more info on Linux MM, see: http://www.linux-mm.org/ . Don't email: <a href=mailto:"dont@xxxxxxxxx";> email@xxxxxxxxx </a>