On Mon, 16 Apr 2018, Christopher Lameter wrote: > On Mon, 16 Apr 2018, Mikulas Patocka wrote: > > > > > > > Or an increase in slab_max_order > > > > But that will increase it for all slabs (often senselessly - i.e. > > kmalloc-4096 would have order 4MB). > > 4MB? Nope.... That is a power of two slab so no wasted space even with > order 0. See this email: https://www.redhat.com/archives/dm-devel/2018-March/msg00387.html If you boot with slub_max_order=10, the kmalloc-8192 cache has 64 pages. So yes, it increases the order of all slab caches (although not up to 4MB). > Its not a senseless increase. The more objects you fit into a slab page > the higher the performance of the allocator. > > > > I need to increase it just for dm-bufio slabs. > > If you do this then others will want the same... If others need it, they can turn on the flag SLAB_MINIMIZE_WASTE too. Mikulas
