> On Thu, Jun 29, 2017 at 5:34 AM, Paolo Bonzini <pbonz...@redhat.com> wrote: > > On 28/06/2017 01:57, Alistair Francis wrote: > > I'm not sure I agree with this change, which is effectively delaying the > > processing of events. The question to me is which handles are > > triggering so fast that QEMU effectively busy waits. > > Yeah, that is what I was trying to figure out, but didn't make much headway. > > I kept seeing zero timeouts, which means that the thread never blocks > and this patch helps a lot.
Perhaps you can use tracepoints? There shouldn't be many handles registered, since on Windows even the GUI actions all go through messages. > > Maybe your QEMUs can get some breath with commit 12f8def0e0 ("win32: > > replace custom mutex and condition variable with native primitives", > > 2017-03-27), since the native primitives are more efficient and TCG 2.8 > > used condvars a lot for qemu_io_proceeded_cond. > > Ok, I will try that. > > Does this mean you don't see the same slowness on QEMU 2.9? I have not tried, but the patch is only working around the real issue, as Fam pointed out. Paolo