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? Since it's not 4.7 material, I'll wait for your experiments and David's remarks. Paolo
