This header only C library measures micro-architectural event diffs between two program locations. To capture the diffs instrument the source as follows.
#include "perf_diff.h"
__perf_handle* h;
int main(int argc, char** argv) {
h = __init_perf(argc, argv); // Setup perf events.
assert(h != NULL);
// Rest of main.
...
}
void some_fn() {
__start_perf(h); // Start event capture.
// Code to measure goes here.
__stop_perf(h); // Stop event capture and flush to disk.
}
The events captured is configured by setting PERF_EVENTS enviornment variable.
Set it to a comma seperated list of events. Event names are same as those listed
by a perf list as pre-defined events. Currently we only support first three
groups of events (i.e: Hardware event, Software event, Hardware cache event)
listed there.
You can control the output file location by setting PERF_OUTPUT. The generated
output will be in csv format.
If you are doing performance optimization work which requires inspecting
micro-architectural event differences between optimizations then you can use
perf-diff.py to generate a table of diffs between the event counts between
two captures.
Usage is as follows.
./perf-diff.py <before> <after>