Re: Hyper-V CPU details
On Thu, Oct 22, 2020 at 10:58:28PM -0400, Matt Coleman wrote: > Hello, > > I'm implementing domainGetVcpus and could use some guidance on what > value to use for virVcpuInfo->cpu. > > Hyper-V does not allow the user to pin vCPUs to host CPUs and doesn't > allow the user to see which host CPU a vCPU is currently running on. > Since it's a type 1 hypervisor, none of its scheduling data is > available to the Windows userspace: there aren't any processes or > threads that correspond to vCPUs that I could query the OS scheduler > about. > > My code currently sets it to -1, which produces the following `virsh > vcpuinfo` output for a running VM with two cores: > > VCPU: 0 > CPU:-1 > State: running > CPU time: 1684.5s > CPU Affinity: > > VCPU: 1 > CPU:-1 > State: running > CPU time: 1346.0s > CPU Affinity: > > However, this doesn't match the comment in _virVcpuInfo's declaration, > which says that -1 signifies an offline CPU: > > https://gitlab.com/libvirt/libvirt/-/blob/v6.8.0/include/libvirt/libvirt-domain.h#L1918 > > Should I stick with -1? Or, should I introduce -2 as a value that > indicates that the hypervisor doesn't provide that information? Or, is > there some better way to handle this that I'm not aware of? I don't believe there's any way to express this given the current defined API semantics. So I think introducing "-2" is the only viable option. I'd suggest that we introduce some constants for this API #define VIR_DOMAIN_VCPU_INFO_CPU_OFFLINE -1 #define VIR_DOMAIN_VCPU_INFO_CPU_UNAVAILABLE -2 Regards, Daniel -- |: https://berrange.com -o-https://www.flickr.com/photos/dberrange :| |: https://libvirt.org -o-https://fstop138.berrange.com :| |: https://entangle-photo.org-o-https://www.instagram.com/dberrange :|
Re: Hyper-V CPU details
On Thu, Oct 22, 2020 at 11:01 PM Matt Coleman wrote: > > Hello, > > I'm implementing domainGetVcpus and could use some guidance on what > value to use for virVcpuInfo->cpu. > > Hyper-V does not allow the user to pin vCPUs to host CPUs and doesn't > allow the user to see which host CPU a vCPU is currently running on. > Since it's a type 1 hypervisor, none of its scheduling data is > available to the Windows userspace: there aren't any processes or > threads that correspond to vCPUs that I could query the OS scheduler > about. > > My code currently sets it to -1, which produces the following `virsh > vcpuinfo` output for a running VM with two cores: > > VCPU: 0 > CPU:-1 > State: running > CPU time: 1684.5s > CPU Affinity: > > VCPU: 1 > CPU:-1 > State: running > CPU time: 1346.0s > CPU Affinity: > > However, this doesn't match the comment in _virVcpuInfo's declaration, > which says that -1 signifies an offline CPU: > > https://gitlab.com/libvirt/libvirt/-/blob/v6.8.0/include/libvirt/libvirt-domain.h#L1918 > > Should I stick with -1? Or, should I introduce -2 as a value that > indicates that the hypervisor doesn't provide that information? Or, is > there some better way to handle this that I'm not aware of? > I would suggest introducing a new value. The problem with overloading values is that if there's other code expecting that to mean something, it gets confusing really quickly. -- 真実はいつも一つ！/ Always, there's only one truth!
Hyper-V CPU details
Hello, I'm implementing domainGetVcpus and could use some guidance on what value to use for virVcpuInfo->cpu. Hyper-V does not allow the user to pin vCPUs to host CPUs and doesn't allow the user to see which host CPU a vCPU is currently running on. Since it's a type 1 hypervisor, none of its scheduling data is available to the Windows userspace: there aren't any processes or threads that correspond to vCPUs that I could query the OS scheduler about. My code currently sets it to -1, which produces the following `virsh vcpuinfo` output for a running VM with two cores: VCPU: 0 CPU:-1 State: running CPU time: 1684.5s CPU Affinity: VCPU: 1 CPU:-1 State: running CPU time: 1346.0s CPU Affinity: However, this doesn't match the comment in _virVcpuInfo's declaration, which says that -1 signifies an offline CPU: https://gitlab.com/libvirt/libvirt/-/blob/v6.8.0/include/libvirt/libvirt-domain.h#L1918 Should I stick with -1? Or, should I introduce -2 as a value that indicates that the hypervisor doesn't provide that information? Or, is there some better way to handle this that I'm not aware of? -- Matt
