Hi Yu-Che,
On 11/25/25 13:01, Yu-Che Cheng wrote:
Hi Lukasz,
[snip]
There are some differences, though:
- there are more deeps in the freq in time, so more often you would pay extra penalty for the ramp-up again
- some of the ramp-up phases are a bit longer ~100ms instead of ~80ms going from 2GHz to 3.6GHz
Agree. From the visualized frequency changes in the Perfetto traces, it's more obvious that the ramp-up from 2GHz to 3.6GHz becomes much slower and a bit unstable in v6.6.99, and it's also easier to go down to a low frequency after a short idle.
[snip]
I wonder if you had a fix patch for the util_est in your kernel... That fix has been recently backported to 6.6 stable [1].
You might want to try that patch as well, w/ or w/o this revert. IMHO it might be worth to have it on top. It might help the main Chrome task ('CrRendererMain') to stay longer on the biggest cpu, since the util_est would be higher. You can read the discussion that I had back then with PeterZ and VincentG [2].
No, the util_est fix isn't in our kernel yet. It looks like after cherry-picking the fix, without the revert, the Speedometer 2.0 score becomes even slightly higher than that on v6.6.88 (450 ~ 460 vs 435 ~ 440). On the other hand, with both the fix and the revert, the Speedometer score becomes about 475 ~ 480, which is almost the same as using the performance governor (i.e. pinning at the maximum frequency).
Sounds really good to get such score.
It looks like more tasks that originally run on the little cores are migrated to the middle and big cores more often, which also makes CPU7 more likely to stay at a higher frequency during some short idle in the main thread.
Yes, that's the desired behavior.
Also attach the Perfetto trace for both of them:
fix without revert: https://ui.perfetto.dev/#%21/?s=ff4d10bd58982555eada61648786adf6f7187ac3 fix with revert: https://ui.perfetto.dev/#%21/?s=05da3cedfb3851ad694f523ef59d3cd1092d74ae
Thanks for the traces, there are idle periods there as well - cool.
I will link your email with the results for the history in that stable patch backport.
Thanks for sharing those tests' scores. Community works :)
Regards, Lukasz