linux-kernel - Re: [RFC v2 2/2] selftest/cpuidle: Add support for cpuidle latency measurement

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Date:   Sun, 4 Apr 2021 13:04:10 +0530
From:   Pratik Sampat <psampat@...ux.ibm.com>
To:     Doug Smythies <dsmythies@...us.net>
Cc:     rjw@...ysocki.net, Daniel Lezcano <daniel.lezcano@...aro.org>,
        shuah@...nel.org, ego@...ux.vnet.ibm.com, svaidy@...ux.ibm.com,
        Linux PM list <linux-pm@...r.kernel.org>,
        Linux Kernel Mailing List <linux-kernel@...r.kernel.org>,
        linux-kselftest@...r.kernel.org, pratik.r.sampat@...il.com
Subject: Re: [RFC v2 2/2] selftest/cpuidle: Add support for cpuidle latency
 measurement

Hello Doug,

Thanks for your review.

On 02/04/21 4:57 am, Doug Smythies wrote:
> Hi Pratik,
>
> On Thu, Apr 1, 2021 at 4:45 AM Pratik Rajesh Sampat
> <psampat@...ux.ibm.com> wrote:
> ...
>
>> To run this test specifically:
>> $ make -C tools/testing/selftests TARGETS="cpuidle" run_tests
> I have not become any smarter than I was with version 1,
> and still assumed that the "$" meant regular user.
> Please put it as "#" or separate the two steps, compile and run.

Apologies, I missed incorporating the root user discussion we had.
I'll add a sudo past the "$" symbol.

>> There are a few optinal arguments too that the script can take
> optional
>
> Suggest to also specifically mention how to run without re-compile,
>
> # ./cpuidle.sh -v

Sure thing, I'll add a comment specifying this.

> Note also that the test still leaves all idle states disabled when done.

Yes, I missed out enabling all the idle states after the tests are done.
I'll spin a new version where I enable idle states at the end of the experiment
so that the system stays coherent.

>>          [-h <help>]
>>          [-i <run timer tests>]
>>          [-m <location of the module>]
>>          [-o <location of the output>]
>>          [-v <verbose> (run on all cpus)]
>> Default Output location in: tools/testing/selftest/cpuidle/cpuidle.log
> ...
>
>> +cpu_is_online()
>> +{
>> +       cpu=$1
>> +       if [ ! -f "/sys/devices/system/cpu/cpu$cpu/online" ]; then
>> +               echo 0
> incorrect. should be:
>
>> +               echo 1

Right! Thanks for catching this.

> ... Doug

Thank you,
Pratik