Re: [patch] Make slab allocator work with SLAB_MUST_HWCACHE_ALIGN

[Manfred Spraul]

Ravikiran G Thirumalai wrote:

> I am working on a simplistic allocator for alloc_percpu which
> 1. Minimises cache footprint (simple pointer arithmetic to get to each cpus 
>   version
> 2. Does numa aware allocation
> 3. Does not fragment
> 4. Is simple and extends simple pointer arithmetic to get to cpus offsets
>
> I wouldn't be using the slab at all because using slabs would mean using
> NR_CPUs pointers and one extra dereference which is bad as we had found out
> earlier.  But I guess slab will have to do node local allocations for
> other applications.
>  
Interesting. Slab internally uses lots of large per-cpu arrays. 
Alltogether something like around 40 kB/cpu. Right now implemented with 
NR_CPUs pointers. In the long run I'll try to switch to your allocator.

But back to the patch that started this thread: Do you still need the 
ability to set an explicit alignment for slab allocations? If yes, then 
I'd polish my patch, double check all kmem_cache_create callers and then 
send the patch to akpm. Otherwise I'd wait - the patch is not a bugfix.

--
   Manfred

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