perf_event_read_format

The format of the data returned by read() on a perf event fd, as specified by attr.read_format:

struct read_format {
   { u64        value;
     { u64        time_enabled; } && PERF_FORMAT_TOTAL_TIME_ENABLED
     { u64        time_running; } && PERF_FORMAT_TOTAL_TIME_RUNNING
     { u64        id;           } && PERF_FORMAT_ID
   } && !PERF_FORMAT_GROUP

   { u64        nr;
     { u64        time_enabled; } && PERF_FORMAT_TOTAL_TIME_ENABLED
     { u64        time_running; } && PERF_FORMAT_TOTAL_TIME_RUNNING
     { u64        value;
       { u64    id;           } && PERF_FORMAT_ID
     }        cntr[nr];
   } && PERF_FORMAT_GROUP
};