| Date | Wed, 2 May 2012 12:40:37 -0300 | From | Glauber Costa <> | Subject | Re: [PATCH 19/23] slab: per-memcg accounting of slab caches |
| |
>> @@ -3834,11 +3866,15 @@ static inline void __cache_free(struct kmem_cache *cachep, void *objp, >> */ >> void *kmem_cache_alloc(struct kmem_cache *cachep, gfp_t flags) >> { >> - void *ret = __cache_alloc(cachep, flags, __builtin_return_address(0)); >> + void *ret; >> + >> + rcu_read_lock(); >> + cachep = mem_cgroup_get_kmem_cache(cachep, flags); >> + rcu_read_unlock(); > > Don't we need to check in_interrupt(), current, __GFP_NOFAIL every > time we call mem_cgroup_cgroup_get_kmem_cache()? > > I would personally prefer if those checks were put inside > mem_cgroup_get_kmem_cache() instead of having to check for every > caller. >
in_interrupt() yes, __GFP_NOFAIL I don't think so.
__GFP_NOFAIL should lead to a res_counter_charge_nofail() in the end. The name similarity is no coincidence...
From a code style PoV, it makes sense to bundle an in_interrupt() check here, but from a performance PoV, putting it in the callers can help us avoid the price of a function call.
But well, looking at the code, I see it is not there as well... =(
I plan to change memcontrol.h to look like this:
static __always_inline struct kmem_cache * mem_cgroup_get_kmem_cache(struct kmem_cache *cachep, gfp_t gfp) { if (mem_cgroup_kmem_on && current->mm && !in_interrupt()) return __mem_cgroup_get_kmem_cache(cachep, gfp); return cachep; }
|