On 05/19/2016 05:06 PM, Paolo Bonzini wrote: > > > On 19/05/2016 17:03, Christian Borntraeger wrote: >>>> Would this work too and be simpler? >>>> Hmm, your patch does only fiddle with the grow/shrink logic (which might >>>> be a good idea independently of this change), but the original patch >>>> actually takes into account that we have a guaranteed maximum time by a >>>> wakeup timer - IOW we know exactly what the maximum poll time is. >>> >>> Yes, it's different. The question is whether a 10us poll (40,000 clock >>> cycles) has an impact even if it's sometimes wrong. >> >> Valid question. As I said, this change might be something good independent from >> the original patch. (it might make it unnecessary, though) On the other hand >> I can handle ~30 guest entry/exit cycles of a simple exit like diag9c. >> Needs measurement. > > Actually I'm okay with the original patch, and especially on s390 where > the maximum poll time is small it may make a bigger difference. Though > I suppose the timer interrupt is not floating? Right its cpu local. So a timer wakeup would be considered valid (if the timer kicks in before the poll ends - the poll does also check if the timer expires and maybe the hrtimer is a bit late. > > Since it's not 4.7 material, I'll wait for your experiments and David's > remarks. I will try to get both patches scheduled but it might take a while. -- 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
