Re: [PATCH 4/4] arm64: dts: rockchip: Add OPP data for CPU cores on RK3588

From: Dragan Simic
Date: Mon Jan 29 2024 - 02:39:35 EST

Hello Alexey,

On 2024-01-29 01:09, Dragan Simic wrote:
On 2024-01-28 20:14, Alexey Charkov wrote:
On Sun, Jan 28, 2024 at 7:35 AM Dragan Simic <dsimic@xxxxxxxxxxx> wrote:
Just checking, running the test on just two CPU cores was enough to
keep the package temperature at around 80 oC?

No, not even remotely.

I kept the continuous 6 dhrystone threads running on all the other
cores (`taskset -c 0-5 ./dhrystone -t 6 -r 6000`) to let it reach the
throttling temperature. This adds further imprecision to the benchmark
of course, because the governor might choose to throttle some of the
cores that do not participate in the timed benchmarking run, and thus
lend some thermal headroom to the latter. That didn't seem to happen
from my naked-eye observation via `watch "cpupower -c 0,4,6
frequency-info | grep current"`, although I admit that I didn't record
more granular logs of frequency states, and some quick transitions to
lower frequencies could also have happened on the other cores. Don't
think it's a major influence though, because a quick transition back
and forth shouldn't have contributed much to the thermal output.

Thank you for the clarification!

You're right, that might have introduced some inaccuracy into the test
results, and it also made the tests kind of hardly repeatable. On the
other hand, that way the synthetic CPU test feels a bit more like some
real-world CPU load, in which multiple resource-hungry tasks usually
compete for the CPU cores and the thermal budget.

Though, as we know repeatability is the key for a scientific approach,
but it also usually contradicts with simulating real-world loads that
are of rather random nature. Well, testing is hard. :)

I'll think a bit more about all this, and I'll come back with an update.
Maybe I'll also be able to join the testing.

Good news! :) Thanks to Radxa, I'll be able to do the testing on my
side, perhaps in about a week or two. If you agree, it might be the best
to wait for those test results as well; of course, I'll keep thinking
about some kind of a test suite in the meantime, which we should be able
to use on other boards as well.