On Tue, Feb 3, 2015 at 3:14 AM, Lisa Nguyen <lisa.ngu...@linaro.org> wrote:
> On 1 February 2015 at 22:00, Amit Kucheria <amit.kuche...@linaro.org> wrote:
>> On Mon, Feb 2, 2015 at 7:34 AM, Lisa Nguyen <lisa.ngu...@linaro.org> wrote:
>>> Set the sampling_rate to zero if the sampling_rate attribute cannot
>>> be found in either directories listed in the if condition. This will
>>> also resolve minor bugs where the sampling_rate is missing.
>>>
>>> Signed-off-by: Lisa Nguyen <lisa.ngu...@linaro.org>
>>> ---
>>> include/functions.sh | 4 +++-
>>> 1 file changed, 3 insertions(+), 1 deletion(-)
>>>
>>> diff --git a/include/functions.sh b/include/functions.sh
>>> index e3eb140..4486da8 100644
>>> --- a/include/functions.sh
>>> +++ b/include/functions.sh
>>> @@ -164,8 +164,10 @@ wait_latency() {
>>> # consider per-policy governor case
>>> if [ -e $CPU_PATH/$wait_latency_cpu/cpufreq/$gov ]; then
>>> sampling_rate=$(cat
>>> $CPU_PATH/$wait_latency_cpu/cpufreq/$gov/sampling_rate)
>>> - else
>>> + elif [ -e $CPU_PATH/cpufreq/$gov/sampling_rate ]; then
>>> sampling_rate=$(cat $CPU_PATH/cpufreq/$gov/sampling_rate)
>>> + else
>>> + sampling_rate=0
>>> fi
>>> sampling_rate=$((sampling_rate * 1000)) # unit nsec
>>>
>>
>> Hmm, let us think about this a bit. In what situation will be not find
>> a sampling rate for the governor? In the case where we are NOT using
>> ondemand governor. This is expected on Android which uses the
>> interactive governor.
>>
>> So the entire wait_latency() function is going to return somewhat
>> incorrect values when run on Android.
>
> I agree.
>
>> I suggest the following removing this patch from the series and
>> properly fixing this problem by doing tests on ubuntu and android with
>> ondemand and interactive respectively to figure out what variables
>> should be read to get the sampling rate.
>
> The common errors I ran into were these ones without the patch:
>
> + gov=userspace
> + [ -e /sys/devices/system/cpu/cpu0/cpufreq/userspace ]
> + cat /sys/devices/system/cpu/cpufreq/userspace/sampling_rate
> cat: /sys/devices/system/cpu/cpufreq/userspace/sampling_rate: No such
> file or directory
> + sampling_rate=
>
> I'll see what results I get on Ubuntu and Android with ondemand and
> interactive respectively.
Read Documentation/cpu-freq/governors.txt for details on the knobs
available for ondemand. These knobs are specific to each governor for
tuning, so of course you won't find them with the userspace governor.
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