Re: SMP syncronization on AMD processors (broken?)

[Andi Kleen]

Kirill Korotaev <dev@xxxxx> writes:

> Please help with a not simple question about spin_lock/spin_unlock on
> SMP archs. The question is whether concurrent spin_lock()'s should
> acquire it in more or less "fair" fashinon or one of CPUs can starve
> any arbitrary time while others do reacquire it in a loop.

They are not fully fair because of the NUMAness of the system.
Same on many other NUMA systems.

We considered long ago to use queued locks to avoid this, but 
they are quite costly for the uncongested case and never seemed worth it.

So live with it.

-Andi
-
To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
the body of a message to majordomo@xxxxxxxxxxxxxxx
More majordomo info at  http://vger.kernel.org/majordomo-info.html
Please read the FAQ at  http://www.tux.org/lkml/