On 03/05/2018 06:44 AM, Viktor Mihajlovski wrote: > In order to not affect running VMs, refreshing the halted state > is only performed if QEMU supports the query-cpus-fast QAPI. > > Signed-off-by: Viktor Mihajlovski <mihajlov@xxxxxxxxxxxxxxxxxx> > Reviewed-by: Boris Fiuczynski <fiuczy@xxxxxxxxxxxxxxxxxx> > Reviewed-by: Marc Hartmayer <mhartmay@xxxxxxxxxxxxxxxxxx> > --- > src/qemu/qemu_domain.c | 9 +++++++-- > 1 file changed, 7 insertions(+), 2 deletions(-) > BTW: You'll need a patch to docs/news.xml as this is something newsworthy I would think. Although calling it "-fast" there may make people wonder about the "slowness" aspect of the current algorithm. > diff --git a/src/qemu/qemu_domain.c b/src/qemu/qemu_domain.c > index 4079fb3..a5fcf22 100644 > --- a/src/qemu/qemu_domain.c > +++ b/src/qemu/qemu_domain.c > @@ -8801,8 +8801,13 @@ qemuDomainRefreshVcpuHalted(virQEMUDriverPtr driver, > return 0; > > /* The halted state is interresting only on s390(x). On other platforms "interesting" > - * the data would be stale at the time when it would be used. */ > - if (!ARCH_IS_S390(vm->def->os.arch)) > + * the data would be stale at the time when it would be used. > + * Calling qemuMonitorGetCpuHalted() can adversely affect the running > + * VM's performance unless QEMU supports query-cpus-fast. > + */ > + if (!ARCH_IS_S390(vm->def->os.arch) || > + !virQEMUCapsGet(QEMU_DOMAIN_PRIVATE(vm)->qemuCaps, > + QEMU_CAPS_QUERY_CPUS_FAST)) So IOW systems that reported this previously that don't get the updated QEMU bits (e.g. > 2.12) would now stop reporting halted only because of the adverse performance impact. But that is a data change and "policy" we'd be inflicting upon them which maybe they don't care about. Perhaps in that case we should have a "flag" that handles whether the caller cares or not. I understand the motivation and reasoning; however, based on how such things have been historically acked or nacked, I'm leaning towards saying this patch shouldn't go in. John > return 0; > > if (qemuDomainObjEnterMonitorAsync(driver, vm, asyncJob) < 0) > -- libvir-list mailing list libvir-list@xxxxxxxxxx https://www.redhat.com/mailman/listinfo/libvir-list
