On 11-01-18, 16:44, Pavan Kondeti wrote:
What is the WALT window size (walt_ravg_window) in your setup? I see it is 20 msec here [1], but just want to double confirm. Reducing WALT window size makes it more responsive. Have you tried with different window size like 10 msec?
Hi Pavan,
Sorry for the delayed response, I wanted to make sure I get back after running some tests with the 10 ms thing.
- So yes, the earlier tests were with the 20 ms window size. I have tested it again with 10 ms and the results have surely improved significantly. No power numbers yet.
- Another thing to notice is that the PCMark Video-decoding and Work-V2 tests show proper numbers after this change, which were failing earlier and giving 0 as the results.
Few observations from pelt vs walt tests I performed:
- The cpufreq statistics show that with walt the big cluster runs for a significantly longer period of time at the highest OPP compared to pelt. Which plays a significant role boosting Walt's performance numbers.
This may happen due to one of the two reasons (or both): - The slope of the signal is higher and so cpu_util() increases rapidly. - We put (more) tasks on the bigger CPU quickly with Walt.
My test shows that the main reason is the second one and it isn't really about the slope of the signal thing.
- I also performed Walt tests without walt_cpu_high_irqload() thing and the results weren't significantly different than walt with it. So that isn't playing a big role either.
Until now my tests show that pelt 8 or 16 with util-est (from patrick) show very good results (just a bit lower than walt on specific cases). The cpufreq stat figures are also equivalent to walt and so we must not be doing bad energy wise.
I am quite sure that using sched-tune to boost up things, we will more quickly move the tasks to the big cluster with pelt 8/16 and that may help us getting results equivalent to that of walt. Will do that going forward..
Thanks.
-- viresh