Re: [PATCH] slab.c cleanup

From: Arnd Bergmann (arnd@bergmann-dalldorf.de)
Date: Sun Mar 23 2003 - 16:24:10 EST


Brian Gerst wrote:

> Manfred Spraul wrote:
>>
>> No, the patch is a bad thing: It means that everyone who does
>> kmalloc(32,) now allocates 128 bytes, i.e. 3/4 wasted. IMHO not acceptable.
>
> Perhaps, but it currently is already allocating 128 bytes for smaller
> caches, because the cache is created with SLAB_HWCACHE_ALIGN. So we
> ended up with redundantly sized caches.

Doesn't this code in kmem_cache_create() handle this already?

> if (flags & SLAB_HWCACHE_ALIGN) {
> /* Need to adjust size so that objs are cache aligned. */
> /* Small obj size, can get at least two per cache line. */
> while (size < align/2)
> align /= 2;
> size = (size+align-1)&(~(align-1));
> }

        Arnd <><
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