On 06.12.2016 13:10, Peter Krempa wrote: > On Tue, Dec 06, 2016 at 13:01:48 +0100, Viktor Mihajlovski wrote: >> On 06.12.2016 12:33, Peter Krempa wrote: >>> On Fri, Nov 25, 2016 at 14:53:07 +0530, Nitesh Konkar wrote: > > [...] > >>> Additionally we historically treat the "all bits set" cpu map >>> as that there is no pinning configured. This would change this >>> behavior. When the VM is started, the real cpu map should be >>> returned, but for the config time I think the current state is >>> correct and doing your change would be incorrect. >> I have no strong opinion on whether the CPU mask should match the >> host online mask for the defined case, but the "all bits set" map >> will change with the old code as well, if new CPUs are added via >> hotplug. > > CPU hotplug on the host is very uncommon and thus not tested very > well. > I can assure you that is very common on Linux running on z Systems and also widely used by customers. With the patchset in https://www.redhat.com/archives/libvir-list/2016-November/msg01320.html it can also be reliably uses with libvirt. >> The crux is that we don't have any way to find out there's in >> fact no pinning in place for a process nor a way to "unpin" it. > > That is true indeed. It's not possible via the API. It's fully > possible via XML though. > > For unpinning I have an unfinished series adding a flag to remove > pinning since since any other method is not reliable enough. > > Finally I think that the "all ones" bitmap should cover the full > map the user sends to libvirt. This would differentiate it from the > "pinned to current full set of cpus" case. > -- Mit freundlichen Grüßen/Kind Regards Viktor Mihajlovski IBM Deutschland Research & Development GmbH Vorsitzender des Aufsichtsrats: Martina Köderitz Geschäftsführung: Dirk Wittkopp Sitz der Gesellschaft: Böblingen Registergericht: Amtsgericht Stuttgart, HRB 243294 -- libvir-list mailing list libvir-list@xxxxxxxxxx https://www.redhat.com/mailman/listinfo/libvir-list
