On Fri, Oct 27, 2017 at 10:57:13AM +0530, Aneesh Kumar K.V wrote: > > > On 10/27/2017 10:04 AM, Paul Mackerras wrote: > >How do we interpret these numbers? Are they times, or speed? Is > >larger better or worse? > > Sorry for not including the details. They are time in seconds. Test case is > a modified mmap_bench included in powerpc/selftest. > > > > >Can you give us the mean and standard deviation for each set of 5 > >please? > > > > powernv without patch > median= 51.432255 > stdev = 0.370835 > > with patch > median = 50.739922 > stdev = 0.06419662 > > pseries without patch > median = 116.617884 > stdev = 3.04531023 > > with patch no hcall > median = 119.42494 > stdev = 0.85874552 > > with patch and hcall > median = 117.735808 > stdev = 2.7624151
So on powernv, the patch set *improves* performance by about 1.3% (almost 2 standard deviations). Do we know why that is? On pseries, performance is about 2.4% worse without new hcalls, but that is less than 1 standard deviation. With new hcalls, performance is 0.95% worse, only a third of a standard deviation. I think we need to do more measurements to try to get a more accurate picture here. Were the pseries numbers done on KVM or PowerVM? Could you do a set of measurements on the other one too please? (I assume the numbers with the new hcall were done on KVM, and can't be done on PowerVM.) Paul.
