Profiler: add Self CPU Time Total, CPU time total and other general improvements (#19378)
Summary:
Pull Request resolved: https://github.com/pytorch/pytorch/pull/19378
Function profile events are typically nested. In this diff I
add parent child relationship to the intervals. This way we can
attribute self time easily. As a result, user printing a table from a
profiler trace gets self cpu time.
This diff doesn't try to address CUDA self time as CUDA kernels are
already getting special care in the profiler.
There are also some other minor improvements. Like reporting total CPU
time spent, reversed sorting, aggregated data after the table,
etc.
There is a new unit test added which tests more functionality than
previous profiler test
Reviewed By: zheng-xq
Differential Revision: D14988612
fbshipit-source-id: 2ee6f64f0a4d0b659c6b23c0510bf13aa46f07dc
