Hi, I looked a bit at SLUB debugging capabilities and first thing I noticed is there's no static key guarding the runtime enablement as is common for similar debugging functionalities, so here's a RFC to add it. Can be further improved if there's interest. It's true that in the alloc fast path the debugging check overhead is AFAICS amortized by the per-cpu cache, i.e. when the allocation is from there, no debugging functionality is performed. IMHO that's kinda a weakness, especially for SLAB_STORE_USER, so I might also look at doing something about it, and then the static key might be more critical for overhead reduction. In the freeing fast path I quickly checked the stats and it seems that in do_slab_free(), the "if (likely(page == c->page))" is not as likely as it declares, as in the majority of cases, freeing doesn't happen on the object that belongs to the page currently cached. So the advantage of a static key in slow path __slab_free() should be more useful immediately. Vlastimil Babka (2): mm, slub: introduce static key for slub_debug mm, slub: add missing kmem_cache_debug() checks mm/slub.c | 31 +++++++++++++++++++++++++++++-- 1 file changed, 29 insertions(+), 2 deletions(-) -- 2.21.0
