Messages in this thread | | | Date | Wed, 7 Nov 2012 08:04:03 +0100 | From | Glauber Costa <> | Subject | Re: [PATCH v6 19/29] memcg: infrastructure to match an allocation to the right cache |
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On 11/06/2012 01:28 AM, Andrew Morton wrote: > On Thu, 1 Nov 2012 16:07:35 +0400 > Glauber Costa <glommer@parallels.com> wrote: > >> +static __always_inline struct kmem_cache * >> +memcg_kmem_get_cache(struct kmem_cache *cachep, gfp_t gfp) > > I still don't understand why this code uses __always_inline so much. > > I don't recall seeing the compiler producing out-of-line versions of > "static inline" functions (and perhaps it has special treatment for > functions which were defined in a header file?). > > And if the compiler *does* decide to uninline the function, perhaps it > knows best, and the function shouldn't have been declared inline in the > first place. > > > If it is indeed better to use __always_inline in this code then we have > a heck of a lot of other "static inline" definitions whcih we need to > convert! So, what's going on here? >
The original motivation is indeed performance related. We want to make sure it is inline so it will figure out quickly the "I am not a memcg user" case and keep it going. The slub, for instance, is full of __always_inline functions to make sure that the fast path contains absolutely no function calls. So I was just following this here.
I can remove the marker without a problem and leave it to the compiler if you think it is best
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