On Tue, 31 Jan 2023 at 22:49, Michal Prívozník <mpriv...@redhat.com> wrote:
> On 1/31/23 13:43, Dipanjan Das wrote: > > Hello, > > > > I am getting the following error message when trying to run a VM with > > the emulatorpin cpuset set to a value - > > > > "cannot set CPU affinity on process 78: Invalid argument". > > > > Note that removing the emulatorpin leads to the VM running successfully. > > > > The core that I am setting for the emulatorpin cpuset is present on the > > system and is not in the isolcpus set of the host. > > The question is, whether the container that libvirtd runs in is allowed > to run on the selected cpuset. I mean, you can have a cgroup that allows > a subset of physical CPUs, and when a process running within the cgroup > tries to set affinity to a CPU that's not allowed it gets EINVAL. > Makes sense. I am now wondering whether we can check the cgroups on the host or inside the containers to confirm that this is the case. Since I am setting the emulator pin thread to a known cpu, being able to check whether the cpu is in the cpu subset of the cgroup might be a quick way to find the problem. > > The function this error message comes from is: virProcessSetAffinity() > (the linux version) > > https://gitlab.com/libvirt/libvirt/-/blob/master/src/util/virprocess.c#L445 > > Another reason for the error might be insufficient permissions (though > the man page of sched_setaffinity() says you'd get an EPERM so maybe not). > > > > > Any suggestions on what could be the problem? Any pointers to how to > > debug the issue would help greatly too. > > Turning on debug logs is a good start. From there you'd need a trained > eye to see the code path, but if you post a link to the logs here I'll > try to help. > > Thank you very much. Should I enable debug logs for any specific module(s) or for all of them?
