On 26/05/2016 12:26, Paolo Bonzini wrote: > As discussed on IRC, I would like to understand why the adaptive > adjustment of halt_poll_ns is failing. It seems like you have so few > halts that you don't get halt_poll_ns>0. Yet, when the VM halts, it's > very close to the timer tick---often enough for this patch to have an > effect. > > Please send a trace of halt_poll_ns_grow and halt_poll_ns_shrink > tracepoints, so that we can find out more about this.
And 30 seconds after I wrote this email, you told me on IRC that the guest had HZ=1000 and the module parameter was set to 1 ms in order to _really_ benefit from the patch. So basically you could obtain the same effect with idle=poll in the guest. This explains why your reported results were not so great (as David noted). Thanks, Paolo
