On Wed, Sep 04, 2013 at 10:17:46AM +0800, Wanpeng Li wrote: > Hi Joonsoo, > On Mon, Sep 02, 2013 at 05:38:54PM +0900, Joonsoo Kim wrote: > >This patchset implements byte sized indexes for the freelist of a slab. > > > >Currently, the freelist of a slab consist of unsigned int sized indexes. > >Most of slabs have less number of objects than 256, so much space is wasted. > >To reduce this overhead, this patchset implements byte sized indexes for > >the freelist of a slab. With it, we can save 3 bytes for each objects. > > > >This introduce one likely branch to functions used for setting/getting > >objects to/from the freelist, but we may get more benefits from > >this change. > > > >Below is some numbers of 'cat /proc/slabinfo' related to my previous posting > >and this patchset. > > > > > >* Before * > ># name <active_objs> <num_objs> <objsize> <objperslab> <pagesperslab> : tunables [snip...] > >kmalloc-512 525 640 512 8 1 : tunables 54 27 0 : slabdata 80 80 0 > >kmalloc-256 210 210 256 15 1 : tunables 120 60 0 : slabdata 14 14 0 > >kmalloc-192 1016 1040 192 20 1 : tunables 120 60 0 : slabdata 52 52 0 > >kmalloc-96 560 620 128 31 1 : tunables 120 60 0 : slabdata 20 20 0 > >kmalloc-64 2148 2280 64 60 1 : tunables 120 60 0 : slabdata 38 38 0 > >kmalloc-128 647 682 128 31 1 : tunables 120 60 0 : slabdata 22 22 0 > >kmalloc-32 11360 11413 32 113 1 : tunables 120 60 0 : slabdata 101 101 0 > >kmem_cache 197 200 192 20 1 : tunables 120 60 0 : slabdata 10 10 0 > > > >* After my previous posting(overload struct slab over struct page) * > ># name <active_objs> <num_objs> <objsize> <objperslab> <pagesperslab> : tunables [snip...] > >kmalloc-512 527 600 512 8 1 : tunables 54 27 0 : slabdata 75 75 0 > >kmalloc-256 210 210 256 15 1 : tunables 120 60 0 : slabdata 14 14 0 > >kmalloc-192 1040 1040 192 20 1 : tunables 120 60 0 : slabdata 52 52 0 > >kmalloc-96 750 750 128 30 1 : tunables 120 60 0 : slabdata 25 25 0 > >kmalloc-64 2773 2773 64 59 1 : tunables 120 60 0 : slabdata 47 47 0 > >kmalloc-128 660 690 128 30 1 : tunables 120 60 0 : slabdata 23 23 0 > >kmalloc-32 11200 11200 32 112 1 : tunables 120 60 0 : slabdata 100 100 0 > >kmem_cache 197 200 192 20 1 : tunables 120 60 0 : slabdata 10 10 0 > > > >kmem_caches consisting of objects less than or equal to 128 byte have one more > >objects in a slab. You can see it at objperslab. > > I think there is one less objects in a slab after observing objperslab. Yes :) I did a mistake when I attached the data about this patchset. The results of *Before* and *After* should be exchanged. Thanks for pointing out that. Thanks. -- 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>