Hello
I have a new AMD A8 system and perf multiplexing support is acting weird.
If I run the perf_event_tests check_multiplexing test it fails like this:
Event TotalCount RawCount Scale
ScaledCount Error
0 500282143 150403975 -2.00 (c8050b5 fffffffff9c224ef)
-300807950 160.13%
So the problem is that the TOTAL_TIME_RUNNING value is negative, which as
far as I know shouldn't be possible. I can't seem to track down
why this would happen, and the same kernel (4.2-rc3) running on a Haswell
machine doesn't have this problem.
I tried to replicate the problem using perf, but for some reason I can't
get perf to multiplex on any of my machines. That used to transparently
work didn't it?
here's the result on the haswell machine
perf stat -e
cycles,instructions,cycles,instructions,cycles,instructions,cycles,instructions
sleep 5
Performance counter stats for 'sleep 5':
1,354,527 cycles
1,934,694 instructions # 1.76 insns per cycle
1,521,148 cycles
1,934,694 instructions # 1.76 insns per cycle
1,521,148 cycles
1,223,321 instructions # 1.11 insns per cycle
[13.61%]
<not counted> cycles
<not counted> instructions
5.003651781 seconds time elapsed
Vince
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