On Tue, 22 Jul 2014, Peter Zijlstra wrote: > Anyway, there is one big fail in the entire futex stack that we 'need' > to sort some day and that is NUMA. Some people (again database people) > explicitly do not use futexes and instead use sysvsem because of this. > > The problem with numa futexes is that because they're vaddr based there > is no (persistent) node information. You always end up having to fall > back to looking in all nodes before you can guarantee there is no > matching futex. > > One way to achieve it is by extending the futex value to include a node > number, but that's obviously a complete ABI break. Then again, it should > be pretty straight fwd, since the node number doesn't need to be part of > the actual atomic update part, just part of the userspace storage. So you want per node hash buckets, right? Fair enough, but how do you make sure, that no thread/process on a different node is fiddling with that "node bound" futex as well? Thanks, tglx -- To unsubscribe from this list: send the line "unsubscribe linux-doc" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
