What does the "scaled from 66.58%" means?? What is scaled??

What does the "scaled from 66.58%" means?? What is scaled??

[Peipei Wang]

perf stat -B dd if=/dev/zero of=/dev/null count=1000000

1000000+0 records in
1000000+0 records out
512000000 bytes (512 MB) copied, 0.956217 s, 535 MB/s

 Performance counter stats for 'dd if=/dev/zero of=/dev/null count=1000000':

            5,099 cache-misses             #      0.005 M/sec (scaled
from 66.58%)
          235,384 cache-references         #      0.246 M/sec (scaled
from 66.56%)
        9,281,660 branch-misses            #      3.858 %     (scaled
from 33.50%)
      240,609,766 branches                 #    251.559 M/sec (scaled
from 33.66%)
    1,403,561,257 instructions             #      0.679 IPC   (scaled
from 50.23%)
    2,066,201,729 cycles                   #   2160.227 M/sec (scaled
from 66.67%)
              217 page-faults              #      0.000 M/sec
                3 CPU-migrations           #      0.000 M/sec
               83 context-switches         #      0.000 M/sec
       956.474238 task-clock-msecs         #      0.999 CPUs

       0.957617512  seconds time elapsed

Hi, all. I get a data from the
page:https://code.google.com/p/kernel/wiki/PerfUserGuide,
Can anyone explain to me the meaning of "scaled from", and from which
get the 66.58% or 33.50%??

Best wishes.
Yours,
Wang Peipei

Re: What does the "scaled from 66.58%" means?? What is scaled??

[Cody P Schafer]

On 06/24/2013 03:37 PM, Peipei Wang wrote:
> perf stat -B dd if=/dev/zero of=/dev/null count=1000000
>
> 1000000+0 records in
> 1000000+0 records out
> 512000000 bytes (512 MB) copied, 0.956217 s, 535 MB/s
>
>   Performance counter stats for 'dd if=/dev/zero of=/dev/null count=1000000':
>
>              5,099 cache-misses             #      0.005 M/sec (scaled
> from 66.58%)
>            235,384 cache-references         #      0.246 M/sec (scaled
> from 66.56%)
>          9,281,660 branch-misses            #      3.858 %     (scaled
> from 33.50%)
>        240,609,766 branches                 #    251.559 M/sec (scaled
> from 33.66%)
>      1,403,561,257 instructions             #      0.679 IPC   (scaled
> from 50.23%)
>      2,066,201,729 cycles                   #   2160.227 M/sec (scaled
> from 66.67%)
 > ...
> Can anyone explain to me the meaning of "scaled from", and from which
> get the 66.58% or 33.50%??

The scaling indicates that we had to time slice performance events 
because we couldn't enable them all at once.

The 33% indicates that that event was only active 33% of the time, so 
we've scaled it (multiplied by 3, in this case) with the assumption that 
it would show up with the same frequency during the times it was 
disabled. (Same for 66%).