Messages in this thread | | | Subject | Re: [PATCH v2 2/2] perf parse-events: Architecture specific leader override | From | John Garry <> | Date | Fri, 19 Nov 2021 14:47:43 +0000 |
| |
On 18/11/2021 22:06, Ian Rogers wrote: > Currently topdown events must appear after a slots event: > > $ perf stat -e '{slots,topdown-fe-bound}' /bin/true > > Performance counter stats for '/bin/true': > > 3,183,090 slots > 986,133 topdown-fe-bound > > Reversing the events yields: > > $ perf stat -e '{topdown-fe-bound,slots}' /bin/true > Error: > The sys_perf_event_open() syscall returned with 22 (Invalid argument) for event (topdown-fe-bound). > > For metrics the order of events is determined by iterating over a > hashmap, and so slots isn't guaranteed to be first which can yield this > error. > > Change the set_leader in parse-events, called when a group is closed, so > that rather than always making the first event the leader, if the slots > event exists then it is made the leader. It is then moved to the head of > the evlist otherwise it won't be opened in the correct order. > > The result is: > > $ perf stat -e '{topdown-fe-bound,slots}' /bin/true
Just curious - does this just affect topdown events? I think x86 is the only arch which has them.
Thanks, John
| |