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Commit 6559dea8 authored by Pavankumar Kondeti's avatar Pavankumar Kondeti Committed by Satya Durga Srinivasu Prabhala
Browse files

sched: Add trace point to track preemption disable callers 



Add trace point to track preemption disable callers to
isolate issues unrelated to scheduler and improve debug
turn around time.

Change-Id: If9303b7165167e8f79cd339929daf4afc31a61c4
Signed-off-by: default avatarPavankumar Kondeti <pkondeti@codeaurora.org>
Signed-off-by: default avatarSatya Durga Srinivasu Prabhala <satyap@codeaurora.org>
parent 4cec0cd6

include/linux/sched/sysctl.h

+6 −0
Original line number Diff line number Diff line
@@ -48,6 +48,12 @@ walt_proc_update_handler(struct ctl_table *table, int write, 


#endif



#if defined(CONFIG_DEBUG_PREEMPT) || defined(CONFIG_PREEMPT_TRACER) || \

					defined(CONFIG_PREEMPTIRQ_EVENTS)

extern unsigned int sysctl_preemptoff_tracing_threshold_ns;



#endif



enum sched_tunable_scaling {

	SCHED_TUNABLESCALING_NONE,

	SCHED_TUNABLESCALING_LOG,

include/trace/events/sched.h

+32 −0
Original line number Diff line number Diff line
@@ -1298,6 +1298,38 @@ TRACE_EVENT(sched_isolate, 
		__entry->time, __entry->isolate)

);



TRACE_EVENT(sched_preempt_disable,



	TP_PROTO(u64 delta, bool irqs_disabled,

			unsigned long caddr0, unsigned long caddr1,

			unsigned long caddr2, unsigned long caddr3),



	TP_ARGS(delta, irqs_disabled, caddr0, caddr1, caddr2, caddr3),



	TP_STRUCT__entry(

		__field(u64, delta)

		__field(bool, irqs_disabled)

		__field(void*, caddr0)

		__field(void*, caddr1)

		__field(void*, caddr2)

		__field(void*, caddr3)

	),



	TP_fast_assign(

		__entry->delta = delta;

		__entry->irqs_disabled = irqs_disabled;

		__entry->caddr0 = (void *)caddr0;

		__entry->caddr1 = (void *)caddr1;

		__entry->caddr2 = (void *)caddr2;

		__entry->caddr3 = (void *)caddr3;

	),



	TP_printk("delta=%llu(ns) irqs_d=%d Callers:(%pf<-%pf<-%pf<-%pf)",

				__entry->delta, __entry->irqs_disabled,

				__entry->caddr0, __entry->caddr1,

				__entry->caddr2, __entry->caddr3)

);



#include "walt.h"



#endif /* CONFIG_SMP */

kernel/sched/core.c

+37 −1
Original line number Diff line number Diff line
@@ -88,6 +88,12 @@ int sysctl_sched_rt_runtime = 950000; 
/* CPUs with isolated domains */

cpumask_var_t cpu_isolated_map;



/*

 * preemptoff stack tracing threshold in ns.

 * default: 1ms

 */

unsigned int sysctl_preemptoff_tracing_threshold_ns = 1000000UL;



/*

 * __task_rq_lock - lock the rq @p resides on.

 */
@@ -3191,17 +3197,34 @@ u64 scheduler_tick_max_deferment(void) 


#if defined(CONFIG_PREEMPT) && (defined(CONFIG_DEBUG_PREEMPT) || \

				defined(CONFIG_PREEMPT_TRACER))



struct preempt_store {

	u64 ts;

	unsigned long caddr[4];

	bool irqs_disabled;

};



DEFINE_PER_CPU(struct preempt_store, the_ps);

/*

 * If the value passed in is equal to the current preempt count

 * then we just disabled preemption. Start timing the latency.

 */

static inline void preempt_latency_start(int val)

{

	struct preempt_store *ps = &per_cpu(the_ps, raw_smp_processor_id());



	if (preempt_count() == val) {

		unsigned long ip = get_lock_parent_ip();

#ifdef CONFIG_DEBUG_PREEMPT

		current->preempt_disable_ip = ip;

#endif

		ps->ts = sched_clock();

		ps->caddr[0] = CALLER_ADDR0;

		ps->caddr[1] = CALLER_ADDR1;

		ps->caddr[2] = CALLER_ADDR2;

		ps->caddr[3] = CALLER_ADDR3;

		ps->irqs_disabled = irqs_disabled();



		trace_preempt_off(CALLER_ADDR0, ip);

	}

}
@@ -3234,9 +3257,22 @@ NOKPROBE_SYMBOL(preempt_count_add); 
 */

static inline void preempt_latency_stop(int val)

{

	if (preempt_count() == val)

	if (preempt_count() == val) {

		struct preempt_store *ps = &per_cpu(the_ps,

				raw_smp_processor_id());

		u64 delta = sched_clock() - ps->ts;



		/*

		 * Trace preempt disable stack if preemption

		 * is disabled for more than the threshold.

		 */

		if (delta > sysctl_preemptoff_tracing_threshold_ns)

			trace_sched_preempt_disable(delta, ps->irqs_disabled,

						ps->caddr[0], ps->caddr[1],

						ps->caddr[2], ps->caddr[3]);

		trace_preempt_on(CALLER_ADDR0, get_lock_parent_ip());

	}

}



void preempt_count_sub(int val)

{

kernel/sysctl.c

+10 −0
Original line number Diff line number Diff line
@@ -310,6 +310,16 @@ static struct ctl_table kern_table[] = { 
		.mode		= 0644,

		.proc_handler	= proc_dointvec,

	},

#if defined(CONFIG_DEBUG_PREEMPT) || defined(CONFIG_PREEMPT_TRACER) || \

					defined(CONFIG_PREEMPTIRQ_EVENTS)

	{

		.procname       = "preemptoff_tracing_threshold_ns",

		.data           = &sysctl_preemptoff_tracing_threshold_ns,

		.maxlen         = sizeof(unsigned int),

		.mode           = 0644,

		.proc_handler   = proc_dointvec,

	},

#endif

#ifdef CONFIG_SCHED_WALT

	{

		.procname       = "sched_cpu_high_irqload",