perf_counter, sched: Add sched_stat_runtime tracepoint

This allows more precise tracking of how the scheduler accounts
(and acts upon) a task having spent N nanoseconds of CPU time.

Cc: Peter Zijlstra <a.p.zijlstra@chello.nl>
Cc: Mike Galbraith <efault@gmx.de>
Cc: Paul Mackerras <paulus@samba.org>
Cc: Arnaldo Carvalho de Melo <acme@redhat.com>
Cc: Frederic Weisbecker <fweisbec@gmail.com>
LKML-Reference: <new-submission>
Signed-off-by: Ingo Molnar <mingo@elte.hu>

2 files changed, 34 insertions, 0 deletions

diff --git a/include/trace/events/sched.h b/include/trace/events/sched.h
index b48f1ad7c946..4069c43f4187 100644
--- a/include/trace/events/sched.h
+++ b/include/trace/events/sched.h
@@ -380,6 +380,39 @@ TRACE_EVENT(sched_stat_wait,
 );
 
 /*
+ * Tracepoint for accounting runtime (time the task is executing
+ * on a CPU).
+ */
+TRACE_EVENT(sched_stat_runtime,
+
+        TP_PROTO(struct task_struct *tsk, u64 runtime, u64 vruntime),
+
+        TP_ARGS(tsk, runtime, vruntime),
+
+        TP_STRUCT__entry(
+                __array( char,  comm,   TASK_COMM_LEN   )
+                __field( pid_t, pid                     )
+                __field( u64,   runtime                 )
+                __field( u64,   vruntime                        )
+        ),
+
+        TP_fast_assign(
+                memcpy(__entry->comm, tsk->comm, TASK_COMM_LEN);
+                __entry->pid            = tsk->pid;
+                __entry->runtime        = runtime;
+                __entry->vruntime       = vruntime;
+        )
+        TP_perf_assign(
+                __perf_count(runtime);
+        ),
+
+        TP_printk("task: %s:%d runtime: %Lu [ns], vruntime: %Lu [ns]",
+                        __entry->comm, __entry->pid,
+                        (unsigned long long)__entry->runtime,
+                        (unsigned long long)__entry->vruntime)
+);
+
+/*
  * Tracepoint for accounting sleep time (time the task is not runnable,
  * including iowait, see below).
  */
diff --git a/kernel/sched_fair.c b/kernel/sched_fair.c
index aa7f84121016..a097e909e80f 100644
--- a/kernel/sched_fair.c
+++ b/kernel/sched_fair.c
@@ -513,6 +513,7 @@ static void update_curr(struct cfs_rq *cfs_rq)
         if (entity_is_task(curr)) {
                 struct task_struct *curtask = task_of(curr);
 
+                trace_sched_stat_runtime(curtask, delta_exec, curr->vruntime);
                 cpuacct_charge(curtask, delta_exec);
                 account_group_exec_runtime(curtask, delta_exec);
         }