On 02/05/2015 02:20 PM, Paolo Bonzini wrote: > > > On 05/02/2015 19:55, Jan Kiszka wrote: >>> This patch introduces a new module parameter for the KVM module; when it >>> is present, KVM attempts a bit of polling on every HLT before scheduling >>> itself out via kvm_vcpu_block. >> >> Wouldn't it be better to tune this on a per-VM basis? Think of mixed >> workloads with some latency-sensitive and some standard VMs. > > Yes, but: > > 1) this turned out to be very cheap, so a per-host tunable is not too bad; > > 2) it also affects only very few workloads (for example network > workloads can already do polling in the guest) so it only affects few > people; > > 3) long term anyway we want it to auto tune, which is better than tuning > it per-VM. We may want to auto tune it per VM. However, if we make auto tuning work well, I do not think we want to expose a user visible tunable per VM, and commit to keeping that kind of interface around forever. -- To unsubscribe from this list: send the line "unsubscribe kvm" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
