Add tracing support to track sched_ext core events (/sched_ext/sched_ext_event)
to debug and monitor sched_ext schedulers. Also, change the core event type
from u64 to s64 to support negative event values.

ChangeLog v3 -> v4:
 - Replace a missing __u64 in a tracepoint definition to __s64.

ChangeLog v2 -> v3:
 - Change the type of @delta from __u64 to __s64 and make corresponding changes
   in scx_event_stats and scx_qmap.bpf.c.

ChangeLog v1 -> v2:
 - Rename @added field to @delta for clarity.
 - Rename sched_ext_add_event to sched_ext_event.
 - Drop the @offset field to avoid the potential misuse of non-portable numbers.

Changwoo Min (2):
  sched_ext: Change the event type from u64 to s64
  sched_ext: Add trace point to track sched_ext core events

 include/trace/events/sched_ext.h | 19 +++++++++++++++++++
 kernel/sched/ext.c               | 22 ++++++++++++----------
 tools/sched_ext/scx_qmap.bpf.c   | 16 ++++++++--------
 3 files changed, 39 insertions(+), 18 deletions(-)

-- 
2.48.1