On Fri, 14 Feb 2014 10:55:31 +0100 Christian Borntraeger <borntraeger@xxxxxxxxxx> wrote: > On 14/02/14 00:32, Paolo Bonzini wrote: > > Il 13/02/2014 23:54, Christian Borntraeger ha scritto: > >> We had several variants but in the end we tried to come up with a patch that does not > >> influence other architectures. Your proposal would certainly be fine for s390, > >> but what impact does it have on x86, arm, arm64? Will it cause performance regressions? > > > > It may also have the same advantages you got on s390. > > > >> So I think that the patch as is is probably the safest choice until we have some > >> data from x86, arm, arm64, no? > > > > No, using an existing API is always better than inventing a new one. > > OK. > Michael can you rework the series to simply use > " if (waitqueue_active(&vcpu->wq) && !kvm_arch_vcpu_runnable(vcpu)" in kvm_vcpu_on_spin > > and make kvm_arch_vcpu_runnable kvm_cpu_has_interrupt(vcpu) in s390 code? > That should be equivalent for s390 with even simpler code. > It might also help x86 and others. Ok, I will adapt the patch accordingly... > > > > If you post the new patch series, and describe the benchmark you were using, we can reproduce > > it on x86. > > The benchmark was some workload doing lots of semaphore up/down with hundreds > of processes. Will see if I can come up with a minimal test. > > > > -- 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
