On Wed, Dec 13, 2017 at 03:16:13PM +0000, Valentin Schneider wrote: > Hi Leo, > > > On 12/13/2017 02:53 PM, Leo Yan wrote: > >Hi Valentin, > > > >On Wed, Dec 13, 2017 at 02:21:06PM +0000, Valentin Schneider wrote: > >>The following dt entries are added: > >> cpus [0-3] (Cortex A53): > >> - capacity-dmips-mhz = <592>; > >> > >> cpus [4-7] (Cortex A73): > >> - capacity-dmips-mhz = <1024>; > >> > >>Those values were obtained by running dhrystone 2.1 on a > >>HiKey960 with the following procedure: > >>- Offline all CPUs but CPU0 (A53) > >>- Set CPU0 frequency to maximum > >>- Run Dhrystone 2.1 for 20 seconds > >> > >>- Offline all CPUs but CPU4 (A73) > >>- set CPU4 frequency to maximum > >>- Run Dhrystone 2.1 for 20 seconds > >> > >>The results are as follows: > >>A53: 129633887 loops > >>A73: 287034147 loops > >Seems to me the capacity-dmips-mhz should be: > > > >CA53: 129633887 / 20 / 1844 = 3515 > >CA73: 287034147 / 20 / 2362 = 6076 > > > >After normalized to range [0..1024], we could get: > > > >CA53: 592 > >CA73: 1024 > > Yes, that's the "direct approach". I wanted to underline the fact that there > are two different max frequencies so what I followed would be: > > 1) Computing the performance ratio: > (129633887 / 287034147) * 1024 = 462.47 > > 2) Scaling that to the same frequency scale: > 462.47 * (2362/1844) = 592.38 > > Which gives the same end result (it's the same equation but split in two > steps). Also it makes it easy to check that the cpu_capacity sysfs entry for > the A53s gets correctly set (to 462). Yeah, thanks for clear explanation. [...] Thanks, Leo Yan -- To unsubscribe from this list: send the line "unsubscribe devicetree" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
