On 03/28/2012 08:21 PM, Raghavendra K T wrote: > >> >> >> Looks like a good baseline on which to build the KVM >> implementation. We >> might need some handshake to prevent interference on the host >> side with >> the PLE code. >> > > I think I still missed some point in Avi's comment. I agree that PLE > may be interfering with above patches (resulting in less performance > advantages). but we have not seen performance degradation with the > patches in earlier benchmarks. [ theoretically since patch has very > slight advantage over PLE that atleast it knows who should run next ]. The advantage grows with the vcpu counts and overcommit ratio. If you have N vcpus and M:1 overcommit, PLE has to guess from N/M queued vcpus while your patch knows who to wake up. > > So TODO in my list on this is: > 1. More analysis of performance on PLE mc. > 2. Seeing how to implement handshake to increase performance (if PLE + > patch combination have slight negative effect). I can think of two options: - from the PLE handler, don't wake up a vcpu that is sleeping because it is waiting for a kick - look at other sources of pause loops (I guess smp_call_function() is the significant source) and adjust them to use the same mechanism, and ask the host to disable PLE exiting. This can be done incrementally later. > > Sorry that, I could not do more analysis on PLE (as promised last time) > because of machine availability. > > I 'll do some work on this and comeback. But in the meantime, I do not > see it as blocking for next merge window. -- error compiling committee.c: too many arguments to function -- 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
