sched: Add helper nr_context_switches_cpu()

Returns the number of context switches on the specified CPU, which can be used to diagnose rcu stall. Signed-off-by: Zhen Lei <[email protected]>
kernel-patches · Oct 20, 2022 · 091bef2 · 091bef2
1 parent 8dd6f6f
commit 091bef2
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diff --git 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
@@ -5229,6 +5229,11 @@ 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;