Re: [RFC] NUMA futex hashing

From: Nick Piggin
Date: Tue Aug 08 2006 - 12:32:48 EST

Eric Dumazet wrote:

We certainly can. But if you insist of using mmap sem at all, then we have a problem.

rbtree would not reduce cacheline bouncing, so :

We could use a hashtable (allocated on demand) of size N, N depending on NR_CPUS for example. each chain protected by a private spinlock. If N is well chosen, we might reduce lock cacheline bouncing. (different threads fighting on different private futexes would have a good chance to get different cachelines in this hashtable)

See other mail. We already have a hash table ;)

SUSE Labs, Novell Inc.
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