Re: [LTP] [PATCH] cpuctl_fj: replace ps by top to fix cpu usage's computation error

["Jiří Paleček" <jpalecek@web.de>]

On Wed, 20 Jan 2010 03:52:48 +0100, Garrett Cooper <yanegomi@gmail.com>  
wrote:

> On Tue, Jan 19, 2010 at 4:30 PM, Jiri Palecek <jpalecek@web.de> wrote:
>> On Wednesday 06 January 2010 10:47:34 Shi Weihua wrote:
>>> at 2010-1-6 13:24, Garrett Cooper wrote:
>>> > On Tue, Jan 5, 2010 at 8:58 PM, Shi Weihua <shiwh@cn.fujitsu.com>  
>>> wrote:
>>> >> Some abnormal messages outputted in my x86_64.
>>> >> -------------------
>>> >> pid 4622 cpu_usage 0
>>> >> cpuctl_test_fj    1  TFAIL  :  case19    FAIL
>>> >> pid 4646 cpu_usage 0
>>> >> cpuctl_test_fj    1  TFAIL  :  case20    FAIL
>>> >> pid 4670 cpu_usage 63
>>> >> cpuctl_test_fj    1  TFAIL  :  case21    FAIL
>>> >> -------------------
>>> >> I think cpu usage's computation error occured.
>>> >> So I tried to use the oldest arithmetic of cpu usage, fortunately  
>>> it works.
>>> >> Maybe we should replace 'ps' by 'top' in  get_cpu_usage().
>>> >> By the way, I increased the admissible range of cpu usage in  
>>> case21()
>>> >> because it jumps out range of 44-56 sometimes.
>>> >>
>>> >> My patch works now:
>>> >> -------------------
>>> >> pid 20277 cpu_usage 97
>>> >> cpuctl_test_fj    1  TPASS  :  case19    PASS
>>> >> pid 20307 cpu_usage 99
>>> >> cpuctl_test_fj    1  TPASS  :  case20    PASS
>>> >> pid 20336 cpu_usage 55
>>> >> pid 20336 cpu_usage 53
>>> >> pid 20336 cpu_usage 55
>>> >> pid 20336 cpu_usage 57
>>> >> pid 20336 cpu_usage 55
>>> >> pid 20336 cpu_usage 55
>>> >> pid 20336 cpu_usage 55
>>> >> pid 20336 cpu_usage 55
>>> >> pid 20336 cpu_usage 57
>>> >> pid 20336 cpu_usage 53
>>> >> cpuctl_test_fj    1  TPASS  :  case21    PASS
>>> >> -------------------
>>> >>
>>> >> Signed-off-by: Shi Weihua <shiwh@cn.fujitsu.com>
>>> >> ---
>>> >> ---  
>>> ltp-full-20091231/testcases/kernel/controllers/cpuctl_fj/run_cpuctl_test_fj.sh  
>>>      2009-11-16 15:40:40.000000000 +0800
>>> >> +++  
>>> ltp-full-20091231.new/testcases/kernel/controllers/cpuctl_fj/run_cpuctl_test_fj.sh  
>>>  2010-01-06 12:36:32.000000000 +0800
>>> >> @@ -85,7 +85,10 @@ creat_process()
>>> >>
>>> >>  get_cpu_usage()
>>> >>  {
>>> >> -       ps -eo 'pid,pcpu' | awk '$1 == "'$1'" {  
>>> sub(/(\.[[:digit:]])*$/, "", $2); print $2 }'
>>> >> +       top=($(top -b -n 1 -p $1 | tail -2 | head -1))
>>> >> +       top=${top[8]}
>>> >> +       top=`echo $top | awk -F "." '{print $1}'`
>>> >> +       echo "$top"
>>> >>  }
>>> >>
>>> >>  kill_all_pid()
>>> >> @@ -627,7 +630,7 @@ case21()
>>> >>        do
>>> >>                cpu_usage=$(get_cpu_usage $pid)
>>> >>                echo "pid $pid cpu_usage $cpu_usage"
>>> >> -               expr 44 \< "$cpu_usage" \& "$cpu_usage" \< 56 >  
>>> /dev/null 2>&1
>>> >> +               expr 40 \< "$cpu_usage" \& "$cpu_usage" \< 60 >  
>>> /dev/null 2>&1
>>> >>                ret=$?
>>> >>                : $(( top_times+=1 ))
>>> >>        done
>>> >
>>> >     Could you add a set -x to the top of the script so we can see the
>>> > output please? ps --version would be helpful too..
>>>
>>> I wish it can help you.
>>> --------------------- sh -x -----------------------------
>>> + for i in '$(seq 1 $TST_TOTAL)'
>>> + setup
>>
>> [ ... snip ... ]
>>
>> I believe Garrett Cooper meant to send the trace output of the original  
>> script (the one with ps).
>>
>> However, I'm not sure about the awk program there - particularly:
>>
>> sub(/(\.[[:digit:]])*$/, "", $2)
>>
>> should probably be
>>
>> sub(/\.[[:digit:]]*$/, "", $2)
>>
>> (without the group). Not sure if this can actually cause what you see.
>>
>> Also, I think we could simplify it a bit further, to something like  
>> this:
>>
>> get_cpu_usage()
>> {
>>  ps -p $1 -o pcpu= | awk -F "." '{print $1}'
>> }
>>
>> Please, tell me what do you think about it.
>
>     Actually he gave me what I needed (forgot to reply because I

Yes, but it doesn't cast much light on the problem that it didn't work for  
Shi Weihua in the first place.

> didn't star the email); I'm pretty sure that your observation is
> correct: we shouldn't be extracting \. unless we're actually going to
> use it, so the ellipses [\(\)] can be removed.
>     Are we using just the `major' number, or are we using the `minor'
> number in the cpu usage?

You mean integral and fractional part? I guess the integral part only.

Regards
     Jiri Palecek

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