On Sun, Sep 27, 2009 at 03:47:55PM +0200, Avi Kivity wrote: > On 09/27/2009 03:46 PM, Joerg Roedel wrote: >> >>> We can't find exactly which vcpu, but we can: >>> >>> - rule out threads that are not vcpus for this guest >>> - rule out threads that are already running >>> >>> A major problem with sleep() is that it effectively reduces the vm >>> priority relative to guests that don't have spinlock contention. By >>> selecting a random nonrunnable vcpu belonging to this guest, we at least >>> preserve the guest's timeslice. >>> >> Ok, that makes sense. But before trying that we should probably try to >> call just yield() instead of schedule()? I remember someone from our >> team here at AMD did this for Xen a while ago and already had pretty >> good results with that. Xen has a completly other scheduler but maybe >> its worth trying? >> > > yield() is a no-op in CFS. Hmm, true. At least when kernel.sched_compat_yield == 0, which it is on my distro. If the scheduler would give us something like a real_yield() function which asumes kernel.sched_compat_yield = 1 might help. At least its better than sleeping for some random amount of time. Joerg -- To unsubscribe from this list: send the line "unsubscribe kvm" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
