sched_ext: Add trace point to track sched_ext core events

Add tracing support to track sched_ext core events
(/sched_ext/sched_ext_event). This may be useful for debugging sched_ext
schedulers that trigger a particular event.

The trace point can be used as other trace points, so it can be used in,
for example, `perf trace` and BPF programs, as follows:

======
$> sudo perf trace -e sched_ext:sched_ext_event --filter 'name == "SCX_EV_ENQ_SLICE_DFL"'
======

======
struct tp_sched_ext_event {
	struct trace_entry ent;
	u32 __data_loc_name;
	s64 delta;
};

SEC("tracepoint/sched_ext/sched_ext_event")
int rtp_add_event(struct tp_sched_ext_event *ctx)
{
	char event_name[128];
	unsigned short offset = ctx->__data_loc_name & 0xFFFF;
        bpf_probe_read_str((void *)event_name, 128, (char *)ctx + offset);

	bpf_printk("name %s   delta %lld", event_name, ctx->delta);
	return 0;
}
======

Signed-off-by: Changwoo Min <changwoo@igalia.com>
Acked-by: Andrea Righi <arighi@nvidia.com>
Signed-off-by: Tejun Heo <tj@kernel.org>

diff --git a/include/trace/events/sched_ext.h b/include/trace/events/sched_ext.h
index fe19da7315a90d3b8a4c8107b755d8e32071c599..50e4b712735aab41d0b07b929eb679730251f300 100644 (file)
--- a/include/trace/events/sched_ext.h
+++ b/include/trace/events/sched_ext.h
@@ -26,6 +26,25 @@ TRACE_EVENT(sched_ext_dump,
        )
 );
 
+TRACE_EVENT(sched_ext_event,
+           TP_PROTO(const char *name, __s64 delta),
+           TP_ARGS(name, delta),
+
+       TP_STRUCT__entry(
+               __string(name, name)
+               __field(        __s64,          delta           )
+       ),
+
+       TP_fast_assign(
+               __assign_str(name);
+               __entry->delta          = delta;
+       ),
+
+       TP_printk("name %s delta %lld",
+                 __get_str(name), __entry->delta
+       )
+);
+
 #endif /* _TRACE_SCHED_EXT_H */
 
 /* This part must be outside protection */

diff --git a/kernel/sched/ext.c b/kernel/sched/ext.c
index 686629a860f374b3fea946a0ba05071b9e5713d9..debcd1cf2de9b28e2e4ebd98d4301569a0ea83dd 100644 (file)
--- a/kernel/sched/ext.c
+++ b/kernel/sched/ext.c
@@ -1554,6 +1554,7 @@ static DEFINE_PER_CPU(struct scx_event_stats, event_stats_cpu);
  */
 #define scx_add_event(name, cnt) do {                                          \
        this_cpu_add(event_stats_cpu.name, cnt);                                \
+       trace_sched_ext_event(#name, cnt);                                      \
 } while(0)
 
 /**
@@ -1565,6 +1566,7 @@ static DEFINE_PER_CPU(struct scx_event_stats, event_stats_cpu);
  */
 #define __scx_add_event(name, cnt) do {                                                \
        __this_cpu_add(event_stats_cpu.name, cnt);                              \
+       trace_sched_ext_event(#name, cnt);                                      \
 } while(0)
 
 /**