oprofile and ARM A9 hardware counter

[stephane eranian]

Same result for me on CPU1:

top - 16:20:24 up  1:45,  1 user,  load average: 0.29, 0.08, 0.07
Tasks:  70 total,   2 running,  68 sleeping,   0 stopped,   0 zombie
Cpu(s): 30.7%us,  2.7%sy,  0.0%ni, 66.7%id,  0.0%wa,  0.0%hi,  0.0%si,  0.0%st
Mem:    940232k total,   228984k used,   711248k free,    82244k buffers
Swap:   524240k total,        0k used,   524240k free,    91400k cached

  PID USER      PR  NI  VIRT  RES  SHR S %CPU %MEM    TIME+  P COMMAND
 3968 eranian   20   0   644  160  128 R  100  0.0   0:21.98 1 noploop
 3969 eranian   20   0  2184 1056  804 R    3  0.1   0:00.53 0 top
   82 root      20   0     0    0    0 S    1  0.0   0:01.35 0
kworker/0:1

With 3.3.0-rc1, if I revert the clockdomain patch, I get the same result.
So it must be coming from somewhere else, as you suggested.

If the processor was spending time processing interrupts, then this would be
accounted for in as sys time. But that's not what I observe here. It's either
idle or user. That line, leads me to believe that the processor can only run
my program for 30% of the time. The rest is spent idling even though my
program is non-blocking. How could that be possible? Power-saving?


On Mon, Jan 30, 2012 at 3:49 PM, Ming Lei <ming.lei at canonical.com> wrote:
> On Mon, Jan 30, 2012 at 9:43 PM, stephane eranian
> <eranian at googlemail.com> wrote:
>> Same results for me with 3.3.0-rc1 + 5 patches.
>
> In fact, I think the only effect of the patch is to enable pmu
> interrupt handling,
> which may cause so much difference?
>
> Also maybe you should put 'noploop' to run on CPU1 and you may observe
> a more accurate result of 'top'.
>
> On ARM, almost handling of all IRQs from gic is run on CPU0 at default,
> which may cause your issue.
>
>>
>>
>> top - 14:42:34 up 8 min,  1 user,  load average: 0.70, 0.29, 0.15
>> Tasks:  75 total,   2 running,  73 sleeping,   0 stopped,   0 zombie
>> Cpu(s): 32.9%us,  1.3%sy,  0.0%ni, 65.8%id,  0.0%wa,  0.0%hi,  0.0%si,  0.0%st
>> Mem:    940232k total,   118520k used,   821712k free,     8080k buffers
>> Swap:   524240k total,        0k used,   524240k free,    79432k cached
>>
>>   PID USER      PR  NI  VIRT  RES  SHR S %CPU %MEM    TIME+  COMMAND
>>  3868 eranian   20   0   644  160  128 R   99  0.0   0:53.34 noploop
>>  3870 eranian   20   0  2284 1060  804 R    3  0.1   0:00.63 top
>>     1 root      20   0  2564 1532  952 S    0  0.2   0:01.26 init
>>
>> I am connecting to the board via ssh.
>> But the results don't look correct to me.
>
> thanks,
> --
> Ming Lei