Re: [RFC] NUMA futex hashing

From: Jes Sorensen
Date: Tue Aug 08 2006 - 06:05:42 EST

>>>>> "Andi" == Andi Kleen <ak@xxxxxxx> writes:

Andi> Jes Sorensen <jes@xxxxxxx> 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.

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