PAPI overhead on various kernel interfaces
Note these results are *extremely* old. For more recent results please
see here.
Older results
These are the results of running the "papi_cost" test program
with PAPI 4.1.2.1 on a Core2 machine running four different kernels.
The reported value is "average cycles", a smaller value is better.
| Kernel | Start/Stop | Read | Read TS | Accum | Reset |
| 2.6.32-pe | 17749 | 8982 | 9019 | 11519 | 2550 |
| 2.6.35-pe | 8683 | 2089 | 2109 | 4196 | 2084 |
| 2.6.30-perfmon | 9644 | 1200 | 1202 | 3623 | 2406 |
| 2.6.32-perfctr | 5702 | 195 | 203 | 3772 | 3556 |
The poor behaviour on 2.6.32/perf_events is due to various workarounds
that need to be done to properly set up the counters and read out the
data. These were fixed by 2.6.35.
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