Re: [RFC] NUMA futex hashing

Jes Sorensen
2006-08-08T10:07:50Z

>>>>> "Andi" == Andi Kleen <ak@suse.de> writes:

Andi> Jes Sorensen <jes@sgi.com> writes:
>> Using that argument, all you need to do is to add the alignment
>> ____cacheline_aligned_in_smp to the definition of struct
>> futex_hash_bucket and the problem is solved, given that the
>> internode cacheline in a NUMA system is defined to be the same as
>> the SMP cacheline size.

Andi> Yes but it would waste quite a lot of memory and cache. Wasted
Andi> cache = slow.

Compared to the extra level of indirection, I doubt it would be
measurable. The cache space is barely wasted, we're talking
approximately half a cacheline per futex hash bucket in use.

Jes