[PATCH] sched: implement cpu_clock(cpu) high-speed time source

Implement the cpu_clock(cpu) interface for kernel-internal use: high-speed (but slightly incorrect) per-cpu clock constructed from sched_clock(). This API, unused at the moment, will be used in the future by blktrace, by the softlockup-watchdog, by printk and by lockstat. Signed-off-by: Ingo Molnar <mingo@elte.hu>

[PATCH] sched: implement cpu_clock(cpu) high-speed time source
Implement the cpu_clock(cpu) interface for kernel-internal use: high-speed (but slightly incorrect) per-cpu clock constructed from sched_clock(). This API, unused at the moment, will be used in the future by blktrace, by the softlockup-watchdog, by printk and by lockstat. Signed-off-by: Ingo Molnar <mingo@elte.hu>
Ingo Molnar
1 parent 969bb4e403
Showing 2 changed files with 24 additions and 0 deletions Side-by-side Diff
include/linux/sched.h
kernel/sched.c
@@ -1348,6 +1348,13 @@
 #endif
  
 extern unsigned long long sched_clock(void);
+
+/*
+ * For kernel-internal use: high-speed (but slightly incorrect) per-cpu
+ * clock constructed from sched_clock():
+ */
+extern unsigned long long cpu_clock(int cpu);
+
 extern unsigned long long
 task_sched_runtime(struct task_struct *task);
  
@@ -379,6 +379,23 @@
 #define task_rq(p)		cpu_rq(task_cpu(p))
 #define cpu_curr(cpu)		(cpu_rq(cpu)->curr)
  
+/*
+ * For kernel-internal use: high-speed (but slightly incorrect) per-cpu
+ * clock constructed from sched_clock():
+ */
+unsigned long long cpu_clock(int cpu)
+{
+	struct rq *rq = cpu_rq(cpu);
+	unsigned long long now;
+	unsigned long flags;
+
+	spin_lock_irqsave(&rq->lock, flags);
+	now = rq_clock(rq);
+	spin_unlock_irqrestore(&rq->lock, flags);
+
+	return now;
+}
+
 #ifdef CONFIG_FAIR_GROUP_SCHED
 /* Change a task's ->cfs_rq if it moves across CPUs */
 static inline void set_task_cfs_rq(struct task_struct *p)
...	...	@@ -1348,6 +1348,13 @@
1348	1348	#endif
1349	1349
1350	1350	extern unsigned long long sched_clock(void);
	1351	+
	1352	+/*
	1353	+ * For kernel-internal use: high-speed (but slightly incorrect) per-cpu
	1354	+ * clock constructed from sched_clock():
	1355	+ */
	1356	+extern unsigned long long cpu_clock(int cpu);
	1357	+
1351	1358	extern unsigned long long
1352	1359	task_sched_runtime(struct task_struct *task);
1353	1360
...	...	@@ -379,6 +379,23 @@
379	379	#define task_rq(p) cpu_rq(task_cpu(p))
380	380	#define cpu_curr(cpu) (cpu_rq(cpu)->curr)
381	381
	382	+/*
	383	+ * For kernel-internal use: high-speed (but slightly incorrect) per-cpu
	384	+ * clock constructed from sched_clock():
	385	+ */
	386	+unsigned long long cpu_clock(int cpu)
	387	+{
	388	+ struct rq *rq = cpu_rq(cpu);
	389	+ unsigned long long now;
	390	+ unsigned long flags;
	391	+
	392	+ spin_lock_irqsave(&rq->lock, flags);
	393	+ now = rq_clock(rq);
	394	+ spin_unlock_irqrestore(&rq->lock, flags);
	395	+
	396	+ return now;
	397	+}
	398	+
382	399	#ifdef CONFIG_FAIR_GROUP_SCHED
383	400	/* Change a task's ->cfs_rq if it moves across CPUs */
384	401	static inline void set_task_cfs_rq(struct task_struct *p)