Commit 7c182722 authored by Zhen Lei's avatar Zhen Lei Committed by Paul E. McKenney
Browse files

sched: Add helper nr_context_switches_cpu() 



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: default avatarZhen Lei <thunder.leizhen@huawei.com>
Cc: Ingo Molnar <mingo@redhat.com>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Juri Lelli <juri.lelli@redhat.com>
Cc: Vincent Guittot <vincent.guittot@linaro.org>
Cc: Dietmar Eggemann <dietmar.eggemann@arm.com>
Cc: Steven Rostedt <rostedt@goodmis.org>
Cc: Ben Segall <bsegall@google.com>
Cc: Mel Gorman <mgorman@suse.de>
Cc: Daniel Bristot de Oliveira <bristot@redhat.com>
Cc: Valentin Schneider <vschneid@redhat.com>
Reviewed-by: default avatarFrederic Weisbecker <frederic@kernel.org>
Signed-off-by: default avatarPaul E. McKenney <paulmck@kernel.org>
parent 3ca0a6ea

include/linux/kernel_stat.h

+1 −0
Original line number Diff line number Diff line
@@ -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);

kernel/sched/core.c

+5 −0
Original line number Diff line number Diff line
@@ -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;