From: Zhen Lei <thunder.leizhen@xxxxxxxxxx>
Add a function nr_context_switches_cpu() that returns number of context
switches since boot on the specified CPU. This information will be used
to diagnose RCU CPU stalls.
Signed-off-by: Zhen Lei <thunder.leizhen@xxxxxxxxxx>
Cc: Ingo Molnar <mingo@xxxxxxxxxx>
Cc: Peter Zijlstra <peterz@xxxxxxxxxxxxx>
Cc: Juri Lelli <juri.lelli@xxxxxxxxxx>
Cc: Vincent Guittot <vincent.guittot@xxxxxxxxxx>
Cc: Dietmar Eggemann <dietmar.eggemann@xxxxxxx>
Cc: Steven Rostedt <rostedt@xxxxxxxxxxx>
Cc: Ben Segall <bsegall@xxxxxxxxxx>
Cc: Mel Gorman <mgorman@xxxxxxx>
Cc: Daniel Bristot de Oliveira <bristot@xxxxxxxxxx>
Cc: Valentin Schneider <vschneid@xxxxxxxxxx>
Reviewed-by: Frederic Weisbecker <frederic@xxxxxxxxxx>
Signed-off-by: Paul E. McKenney <paulmck@xxxxxxxxxx>
---
include/linux/kernel_stat.h | 1 +
kernel/sched/core.c | 5 +++++
2 files changed, 6 insertions(+)
diff --git a/include/linux/kernel_stat.h b/include/linux/kernel_stat.h
index 898076e173a92..9935f7ecbfb9e 100644
--- a/include/linux/kernel_stat.h
+++ b/include/linux/kernel_stat.h
@@ -52,6 +52,7 @@ DECLARE_PER_CPU(struct kernel_cpustat, kernel_cpustat);
#define kstat_cpu(cpu) per_cpu(kstat, cpu)
#define kcpustat_cpu(cpu) per_cpu(kernel_cpustat, cpu)
+extern unsigned long long nr_context_switches_cpu(int cpu);
extern unsigned long long nr_context_switches(void);
extern unsigned int kstat_irqs_cpu(unsigned int irq, int cpu);
diff --git a/kernel/sched/core.c b/kernel/sched/core.c
index 25b582b6ee5f7..2e40a6c116e1c 100644
--- a/kernel/sched/core.c
+++ b/kernel/sched/core.c
@@ -5282,6 +5282,11 @@ bool single_task_running(void)
}
EXPORT_SYMBOL(single_task_running);
+unsigned long long nr_context_switches_cpu(int cpu)
+{
+ return cpu_rq(cpu)->nr_switches;
+}
+
unsigned long long nr_context_switches(void)
{
int i;
--
2.31.1.189.g2e36527f23
