On Mon, May 18, 2009 at 05:42:41PM +0200, Ingo Molnar wrote: > > * Paul E. McKenney <paulmck@xxxxxxxxxxxxxxxxxx> wrote: > > > > i might be missing something fundamental here, but why not just > > > have per CPU helper threads, all on the same waitqueue, and wake > > > them up via a single wake_up() call? That would remove the SMP > > > cross call (wakeups do immediate cross-calls already). > > > > My concern with this is that the cache misses accessing all the > > processes on this single waitqueue would be serialized, slowing > > things down. In contrast, the bitmask that smp_call_function() > > traverses delivers on the order of a thousand CPUs' worth of bits > > per cache miss. I will give it a try, though. > > At least if you go via the migration threads, you can queue up > requests to them locally. But there's going to be cachemisses > _anyway_, since you have to access them all from a single CPU, and > then they have to fetch details about what to do, and then have to > notify the originator about completion. Ah, so you are suggesting that I use smp_call_function() to run code on each CPU that wakes up that CPU's migration thread? I will take a look at this. Thanx, Paul -- To unsubscribe from this list: send the line "unsubscribe netfilter-devel" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
