linux-kernel - Re: [PATCH v3 0/5] Refactor thermal pressure update to avoid code duplication

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Date:   Fri, 5 Nov 2021 17:46:25 -0500
From:   Steev Klimaszewski <steev@...i.org>
To:     Thara Gopinath <thara.gopinath@...aro.org>,
        Lukasz Luba <lukasz.luba@....com>
Cc:     linux-kernel@...r.kernel.org, linux-pm@...r.kernel.org,
        linux-arm-kernel@...ts.infradead.org,
        linux-arm-msm@...r.kernel.org, sudeep.holla@....com,
        will@...nel.org, catalin.marinas@....com, linux@...linux.org.uk,
        gregkh@...uxfoundation.org, rafael@...nel.org,
        viresh.kumar@...aro.org, amitk@...nel.org,
        daniel.lezcano@...aro.org, amit.kachhap@...il.com,
        bjorn.andersson@...aro.org, agross@...nel.org
Subject: Re: [PATCH v3 0/5] Refactor thermal pressure update to avoid code
 duplication

> [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?

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.