On 11/5/21 6:46 PM, Steev Klimaszewski wrote:
[snip]
Hi,
So IIUC the below logs correctly, you are never hitting boost
frequency (with or without this patch series). Is that correct ?
w.r.t temperature , how are you measuring it? Do you have LMh enabled
or are you using tsens to mitigate cpu temperature ?
Hi,
I was wrong - it does indeed go boost with the patchset applied, it's
just that it doesn't boost up to 2.96GHz very often at all. As noted by
the 0.03% when i ran it while compiling zellij; I reapplied the patches
(and the 6th patch from Lukasz's email) and after boot, 2.96GHz was
showing at 0.39%.
Most tools that read the cpu frequency don't really seem to be well
suited for big.LITTLE, and seem to throw an average of the speed, so
cpufreq-info was the best I have. We're apparently supposed to be using
cpupower these days, but it doesn't seem to know anything about arm64
devices.
Temperature wise, I'm just getting from the sensors, and I am using LMh.
Now, I have to admit, while I've thrown a patch here or there, I'm not
exactly a kernel developer, just enough knowledge to be somewhat
dangerous and know how to backport things. In my mind, and my line of
thinking, I would expect with boost enabled, that the cpu would boost up
to that as often as possible, not require a specific workload to
actually hit it. But then again, I would expect multiple compilation
jobs to be one of the workloads that would?
Hi Steev,
So this depends on the cpufreq governor you are using. By-default arm
systems have sched-util governor enabled. This means you will scale up
to boost depending on cpu load and not always. If you want to ensure you
are always hitting boost frequency, you should enable performance
governor for cpufreq and try.
Also since the defconfig has by default CPU_FREQ_STAT enabled, you
should be able to get statistics out of cpufreq to see the time spent by
a cpu in each frequency. I think cpufreq-info -s should give you this
info. If not, you can explicitly get it for each cpu from
cat /sys/devices/system/cpu/cpu<X>/cpufreq/stats/time_in_state
Regarding temperature, if you have applied all the patches in the sdm845
LMh series and have LMh enabled, cpu throttling starts around 95 degree C.
So I think, the part about never hitting 2.96GHz can be dismissed, and
was simply my lack of knowledge about the cpufreq-info tool's averages.
It does seem however to rarely ever hit 2.96GHz and I would actually
expect it to hit it far more often.
--
Warm Regards
Thara (She/Her/Hers)
