On 01/28/2016 05:51 AM, Joonsoo Kim wrote: > On Wed, Jan 27, 2016 at 02:35:04PM +0100, Vlastimil Babka wrote: >> On 01/14/2016 06:24 AM, Joonsoo Kim wrote: >> > 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 patch doesn't include it. >> >> Can you elaborate? Do we actually need an extendable linked array? Why not just >> store the pointer to the next free object into the object, NULL for the last >> one? I.e. a singly-linked list. We should never need to actually traverse it? > > As Christoph explained, it's the way SLUB manages freed objects. In SLAB > case, it doesn't want to touch object itself. It's one of main difference > between SLAB and SLUB. These objects are cache-cold now so touching object itself > could cause more cache footprint. Hm I see. Although I wouldn't bet on whether the now-freed object is more or less cold than the freelist array itself (regardless of its placement) :) -- 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>