> > > From: seanjc <seanjc@xxxxxxxxxx> > > > > From: Cheng Lin <cheng.lin130@xxxxxxxxxx> > > > > > > > > Introduce vm's max_halt_poll_ns and override_halt_poll_ns to > > > > debugfs. Provide a way to check and modify them. > > > Why? > > If a vm's max_halt_poll_ns has been set using KVM_CAP_HALT_POLL, > > the module parameter kvm.halt_poll.ns will no longer indicate the maximum > > halt pooling interval for that vm. After introducing these two attributes into > > debugfs, it can be used to check whether the individual configuration of the > > vm is enabled and the working value. > But why is max_halt_poll_ns special enough to warrant debugfs entries? There is > a _lot_ of state in KVM that is configurable per-VM, it simply isn't feasible to > dump everything into debugfs. If we want to provide a directly modification interface under /sys for per-vm max_halt_poll_ns, like module parameter /sys/module/kvm/parameters/halt_poll_ns, using debugfs may be worth. Further, if the override_halt_poll_ns under debugfs is set to be writable, it can even achieve the setting of per-vm max_halt_poll_ns, as the KVM_CAP_HALL_POLL interface does. > I do think it would be reasonable to capture the max allowed polling time in > the existing tracepoint though, e.g. Yes, I agree it. It is sufficient to get per-vm max_halt_poll_ns through tracepoint if KVP_CAP_HALL_POLL is used as the unique setting interface. Do you consider it is worth to provide a setting interface other than KVP_CAP_HALL_POLL?
