> Here is the data we get when running benchmark netperf: > > 2. w/ patch: > halt_poll_threshold=10000 -- 15803.89 bits/s -- 159.5 %CPU > halt_poll_threshold=20000 -- 15899.04 bits/s -- 161.5 %CPU > halt_poll_threshold=30000 -- 15642.38 bits/s -- 161.8 %CPU > halt_poll_threshold=40000 -- 18040.76 bits/s -- 184.0 %CPU > halt_poll_threshold=50000 -- 18877.61 bits/s -- 197.3 %CPU > > 3. kvm dynamic poll > halt_poll_ns=10000 -- 15876.00 bits/s -- 172.2 %CPU > halt_poll_ns=20000 -- 15602.58 bits/s -- 185.4 %CPU > halt_poll_ns=30000 -- 15930.69 bits/s -- 194.4 %CPU > halt_poll_ns=40000 -- 16413.09 bits/s -- 195.3 %CPU > halt_poll_ns=50000 -- 16417.42 bits/s -- 196.3 %CPU > Actually I'm not sure how much sense it makes to introduce this pv stuff and the duplicate adaptive halt-polling logic as what has already been done in kvm w/o obvious benefit for real workload like netperf. In addition, as you mentioned offline to me, enable both the patchset and the adaptive halt-polling logic in kvm simultaneously can result in more cpu power consumption. I remembered that David from Google mentioned that Windows Event Objects can get 2x latency improvement in KVM FORUM, which means that the adaptive halt-polling in kvm should be enabled by default. So if the windows guests and linux guests are mixed on the same host, then this patchset will result in more cpu power consumption if the customer enable the polling in the linux guest. Anyway, if the patchset is finally acceptable by maintainer, I will introduce the generic adaptive halt-polling framework in kvm to avoid the duplicate logic. Regards, Wanpeng Li
