On 5 March 2018 at 17:52, Ionela Voinescu ionela.voinescu@arm.com wrote:
On 05/03/18 10:27, Viresh Kumar wrote:
From: Leo Yan leo.yan@linaro.org
The homescreen test-case shows unwanted disturbance on the big CPUs on the Hikey620 platform with Android 4.9. There are multiple reasons for that though.
I think you mean Hikey960 here, as Hikey620 has only cores with the same micro-architecture.
Sure you are correct here.
Are you able to share the test setup and results?
Nothing special in the test case really:
- I merged hikey 4.9 branch with eas-dev branch and was testing it with WALT disabled.
- The homescreen testcase is defined here:
http://git.linaro.org/power/product-codeline.git/tree/wlauto/agendas/homescr...
- enabled traces and energy measurements as well.
- Traces clearly show that some tasks go for the big CPUs.
I was under the impression that in the current configuration, all boosted tasks are also prefer_idle,
We have separate tunables for them. So yes we can control prefer_idle separately I think. The same is done in the above yaml.
so I would not expect any disturbance in that case. I might be wrong, but I'm curious if you had to change the schedtune configuration in order to observe an issue.
Yeah, so the yaml disables prefer_idle in one of the test.
I was looking into the same issue and wondering if this logic should not be applied for both non-latency sensitive scenarios: selection of backup idle CPU (as you've done here) and selection of active CPU, where we would select the lowest capacity one, despite it not having the highest spare. But, I think the scenario involving choosing an active CPU is more complicated as we might want to spread tasks when boosted, rather then pack them.
Well, maybe. I will give more thought on that and see if that will make sense as well. But I didn't try it yet as that was part of the prefer_idle path, and we always prefer the big CPU there.
But this is a more simple case and it would benefit from a wider audience on android gerrit, especially in light of other changes that are considered for find_best_target: https://android-review.googlesource.com/q/strf
Sure, I just wanted to get basic feedback here first (reviews are much easier on email) and then post to gerrit.
-- viresh