simpleperf: update trace offcpu modes.
1. Enforce using cpu-clock/task-clock event when --trace-offcpu
is used. This ensures the weight of samples are always reported
in nanoseconds.
2. Simplify weight calculation of off-cpu samples to be
(Timestamp of next switch on record or sample) - (Timestamp of the
current sample).
3. Always use sample period value as the weight of on-cpu samples.
4. Modify ON_OFF_CPU mode to report on-cpu and off-cpu samples under
different event types. So report tools can filter them.
5. Add MODIFIED_ON_OFF_CPU mode to report on-cpu and off-cpu samples
under the same event type.
Bug: 38383695
Test: run simpleperf_unit_test
Change-Id: I32d10511e0b20c0a673afabdc4f248d1a4750668
4 files changed