----- Original Message ----- > From: "Dennis Jacobfeuerborn" <denni...@conversis.de> > To: engine-devel@ovirt.org > Sent: Tuesday, December 18, 2012 12:30:34 PM > Subject: Re: [Engine-devel] CPU Overcommit Feature > > On 12/17/2012 07:13 PM, Simon Grinberg wrote: > > > > > > ----- Original Message ----- > >> From: "Greg Padgett" <gpadg...@redhat.com> > >> To: "engine-devel" <engine-devel@ovirt.org> > >> Sent: Monday, December 17, 2012 4:37:57 PM > >> Subject: [Engine-devel] CPU Overcommit Feature > >> > >> Hi, > >> > >> I've been working on a feature to allow CPU Overcommitment of > >> hosts > >> in a > >> cluster. This first stage allows the engine to consider host cpu > >> threads > >> as cores for the purposes of VM resource allocation. > >> > >> This wiki page has further details, your comments are welcome! > >> http://www.ovirt.org/Features/cpu_overcommit > > > > Basically looking good. > > Hyperthread though is vendor specific. > > > > For AMD it's Clustered Multi-Thread while for Intel it's > > Hyper-Thread > > Official name is simultaneous multithreading (SMT) but no one > > outside of the academy will recognize that. > > > > in libvirt if I read it right it's <attribute > > name='thread_siblings'> > > > > So why not just call it threads. > > We'll have cpuSockets, cpiCores, and cpuThreads, should be clear > > when in CPU context. > > > > In the GUI just change hyperthreads to CPU threads. While in the > > tool tip explain that it's either AMD Clustered Multi-Thread or > > Intel Hyperthread > > Does this affect only the number of potential vCpus for the guests or > does > this also have an impact on the actual scheduling? > So far I always disabled HT out of fear that a 2 vCpu guest might > actually > be scheduled to run in 2 threads of the same core but now I'm not so > sure > anymore. In the HT case does KVM know that two threads belong to the > same > core and will it only schedule its vCpus on distinct cores? Is there > some > documentation about this somewhere?
This is about the maximum number of vCPUs we can give to a VM. If the machine has 32 Physical cores that are hyperthreaded then do we say the max number of vCPUs for a single VM is 32 or 64. > > Regards, > Dennis > > _______________________________________________ > Engine-devel mailing list > Engine-devel@ovirt.org > http://lists.ovirt.org/mailman/listinfo/engine-devel > _______________________________________________ Engine-devel mailing list Engine-devel@ovirt.org http://lists.ovirt.org/mailman/listinfo/engine-devel