Re: [boost] [chrono] Thread clock compatibility problems on Android

Subject: Re: [boost] [chrono] Thread clock compatibility problems on Android
From: Vicente Botet (vicente.botet_at_[hidden])
Date: 2011-05-14 13:28:48

Libor Bus wrote:
> 
> 
> Vicente Botet wrote:
>> 
>> 
>> 
>>> Regarding process_cpu_clock, I have experienced that following code
>>> provided on Linux wrong text output, while on Windows was ok:
>>> {
>>>    boost::stopwatches::stopclock<> timer;
>>>    ... some work
>>> }
>>> 
>> 
>> Could you give me output on both cases?
>> 
> 
> Consider following code snippet:
> {
>     boost::stopwatches::stopclock<> boost_timer;
>     for( int i = 0; i < 10000000; i++)
>         sqrt( 123.456L);
>     sleep( 1); // sleep 1s
> }
> 
> Text output on windows is:
> real 1.031s, cpu 0.031s (3.0%), user 0.031s, system 0.000s
> while thread clock measures: wall=1031ms, cpu=31ms
> 
> Text output on Android (on Linux was similar) is:
> real 0.001s, cpu 0.000s (23.2%), user 0.000s, system 0.000s
> while thread clock measures: wall=1377ms, cpu=312ms
> 
> Test on Android was around 10x slower because I run it on Android emulator
> (can not test Linux right now). Behaviour on Linux I saw couple of days
> ago was same as on Android, i.e., stopclock provided wrong text output,
> just test was similar fast as on Windows.
> 
> Hope this helps.
> 

On which linux dis you tried?

It seems that the posix process_cpu_clocks is not working on this platform.
This clock uses 

        tms tm;
        clock_t c = ::times( &tm );

Could you dump the values of c and tm.tms_stime + tm.tms_cstime,
tm.tms_utime + tm.tms_cutime,  before and after the sleep?

Thanks,
Vicente

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