Messages in this thread | | | Date | Tue, 21 Mar 2006 19:35:00 +0100 | From | Manfred Spraul <> | Subject | Re: [PATCH] slab: introduce kmem_cache_zalloc allocator |
| |
Pekka J Enberg wrote:
>On Tue, 21 Mar 2006, Andrew Morton wrote: > > >>I've always felt that this was an odd design. Because >> >>a) All that cache-warmth which we get from the constructor's zeroing can >> be lost by the time we get around to using an individual object and >> >>b) The object may be cache-cold by the time we free it, and we'll take >> cache misses just putting it back into a constructed state for >> kmem_cache_free(). And we'll lose that cache warmth by the time we use >> this object again. >> >>So from that POV I think (in my simple way) that this is a good patch. But >>IIRC, Manfred has reasons why it might not be? >> >> > >I assume the design comes from Bonwick's paper which states that the >purpose of object constructor is to support one-time initialization of >objects which we're _not_ doing in this case. > > > I agree - memset just before use is the Right Thing (tm).
One minor point: There are two cache_alloc entry points: __cache_alloc, which is a forced inline function, and kmem_cache_alloc, which is just a wrapper for __cache_alloc. Is it really necessary to call __cache_alloc? The idea is that __cache_alloc is used just by the two high-performance paths: kmem_cache_alloc and kmalloc. Noone else should use __cache_alloc directly.
-- Manfred - To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
| |