Messages in this thread | | | Date | Thu, 05 Feb 2015 20:20:54 +0100 | From | Paolo Bonzini <> | Subject | Re: [PATCH RFC] kvm: x86: add halt_poll module parameter |
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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.
Paolo
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