On 08-01-18, 12:56, Leo Yan wrote:
I may not be suitable person to answser this; just give some background info for this:
I remembered Dietmar used Jankbench for comparing WALT and PELT, the scheduler signals have quite different effect on different testing case. Jankbench's tasks workload I think it's more related with responsiveness but from my understanding PCMark testing case is more related with sustainable workload?
Before I even observed the PELT signal (32ms period) might have better performance result than WALT for the sustainable workload, this is because the PELT signal has much longer decay time so it's more stable than WALT for some special case.
Sure, and the same reason can be used to argue against using WALT as that will have the same (bad) effects ?
And I am not arguing on what's the best one for us here, but rather wanted to show that PELT can be modified with trivial changes to make it perform like WALT and maybe remove WALT support later on from Android as that is never going to be upstreamed.
- I saw you have disabled SchedTune for testing, but SchedTune is quite fatal for Jankbench (Or Uibench) testing. The 'prefer_idle' and boost margin have quite important effect, even WALT signal also need heavily to rely on these knobs for Jankbench tunning. E.g 'prefer_idle' is fatal for reducing janks for UI cases.
I didn't wanted any special effects to trick with my results and wanted least number of variables. I do believe that we will continue to use schedtune and that can be tuned to make WALT and PELT (8) behave in a similar way ?
-- viresh