On 11/27/22 12:05, Hyeonggon Yoo wrote: > On Mon, Nov 21, 2022 at 06:12:00PM +0100, Vlastimil Babka wrote: >> SLUB gets most of its scalability by percpu slabs. However for >> CONFIG_SLUB_TINY the goal is minimal memory overhead, not scalability. >> Thus, #ifdef out the whole kmem_cache_cpu percpu structure and >> associated code. Additionally to the slab page savings, this reduces >> percpu allocator usage, and code size. > > [+Cc Dennis] +To: Baoquan also. > Wondering if we can reduce (or zero) early reservation of percpu area > when #if !defined(CONFIG_SLUB) || defined(CONFIG_SLUB_TINY)? Good point. I've sent a PR as it was [1], but (if merged) we can still improve that during RC series, if it means more memory saved thanks to less percpu usage with CONFIG_SLUB_TINY. [1] https://git.kernel.org/pub/scm/linux/kernel/git/vbabka/slab.git/tag/?h=slab-for-6.2-rc1 >> This change builds on recent commit c7323a5ad078 ("mm/slub: restrict >> sysfs validation to debug caches and make it safe"), as caches with >> enabled debugging also avoid percpu slabs and all allocations and >> freeing ends up working with the partial list. With a bit more >> refactoring by the preceding patches, use the same code paths with >> CONFIG_SLUB_TINY. >> >> Signed-off-by: Vlastimil Babka <vbabka@xxxxxxx> >
