On Fri, Apr 29, 2022 at 08:30:44PM +0800, Muchun Song wrote:
> Most callers of memcg_slab_free_hook() already know the slab, which could
> be passed to memcg_slab_free_hook() directly to reduce the overhead of an
> another call of virt_to_slab(). For bulk freeing of objects, the call of
> slab_objcgs() in the loop in memcg_slab_free_hook() is redundant as well.
> Rework memcg_slab_free_hook() and build_detached_freelist() to reduce
> those unnecessary overhead and make memcg_slab_free_hook() can handle bulk
> freeing in slab_free().
>
> Move the calling site of memcg_slab_free_hook() from do_slab_free() to
> slab_free() for slub to make the code clearer since the logic is weird
> (e.g. the caller need to judge whether it needs to call
> memcg_slab_free_hook()). It is easy to make mistakes like missing calling
> of memcg_slab_free_hook() like fixes of:
>
> commit d1b2cf6cb84a ("mm: memcg/slab: uncharge during kmem_cache_free_bulk()")
> commit ae085d7f9365 ("mm: kfence: fix missing objcg housekeeping for SLAB")
>
> This optimization is mainly for bulk objects freeing. The following numbers
> is shown for 16-object freeing.
>
> before after
> kmem_cache_free_bulk: ~430 ns ~400 ns
>
> The overhead is reduced by about 7% for 16-object freeing.
>
> Signed-off-by: Muchun Song <songmuchun@xxxxxxxxxxxxx>
Hi Vlastimil,
Wolud you mind picking it up? I did not see this patch on the
slab tree.
Thanks.
