mon_event_read
mon_event_read(&rr, r, NULL, rdtgrp,
mon_event_read(&rr, r, hdr, rdtgrp, &hdr->cpu_mask, evt, false);
void mon_event_read(struct rmid_read *rr, struct rdt_resource *r,
mon_event_read(&rr, r, hdr, prgrp, &hdr->cpu_mask, mevt, true);