Perf top always show 0.00

[Nathan Lynch]

On 04/18/2014 12:00 PM, Frank Li wrote:
> I use mx6dq platform. Found below problem.
> 
> Run Perf top. First column always 0, but order look like correct.
> 
>    0.00%  perf          [.] 0x00049420
>      0.00%  [kernel]      [k] kallsyms_expand_symbol.constprop.5
>      0.00%  [kernel]      [k] vsnprintf
>      0.00%  [kernel]      [k] arch_cpu_idle
>      0.00%  [kernel]      [k] format_decode
>      0.00%  [kernel]      [k] number.isra.2
>      0.00%  libc-2.19.so  [.] strstr
>      0.00%  libc-2.19.so  [.] 0x00072498
>      0.00%  libc-2.19.so  [.] memchr
>      0.00%  [kernel]      [k] _raw_spin_unlock_irqrestore
>      0.00%  [kernel]      [k] string.isra.4
>      0.00%  [kernel]      [k] strnlen
>      0.00%  libc-2.19.so  [.] getdelim
>      0.00%  libc-2.19.so  [.] memcpy
>      0.00%  [kernel]      [k] lock_acquire
>      0.00%  libc-2.19.so  [.] strchr
>      0.00%  libc-2.19.so  [.] strcmp
>      0.00%  [kernel]      [k] _raw_spin_unlock_irq
>      0.00%  libc-2.19.so  [.] __libc_calloc
>      0.00%  libc-2.19.so  [.] _IO_feof
>      0.00%  [kernel]      [k] pointer.isra.15

The PMU is possibly worthless:

http://lists.infradead.org/pipermail/linux-arm-kernel/2012-August/113802.html

http://lists.infradead.org/pipermail/linux-arm-kernel/2013-February/151945.html