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Commit c5c90f60 authored by Steve Muckle's avatar Steve Muckle
Browse files

sched: do not set window until sched_clock is fully initialized 



The system initially uses a jiffy-based sched clock. When the platform
registers a new timer for sched_clock, sched_clock can jump backwards.
Once sched_clock_postinit() runs it should be safe to rely on it.

Also sched_clock_cpu() relies on completion of sched_clock_init()
and until that happens sched_clock_cpu() returns zero. This is used
in the irq accounting path which window-based stats relies upon.
So do not set window_start until sched_clock_cpu() is working.

Change-Id: Ided349de8f8554f80a027ace0f63ea52b1c38c68
Signed-off-by: default avatarSteve Muckle <smuckle@codeaurora.org>
parent 51c75088

include/linux/sched.h

+1 −0
Original line number Diff line number Diff line
@@ -1973,6 +1973,7 @@ extern u64 sched_clock_cpu(int cpu); 




extern void sched_clock_init(void);

extern int sched_clock_initialized(void);



#ifndef CONFIG_HAVE_UNSTABLE_SCHED_CLOCK

static inline void sched_clock_tick(void)

kernel/sched/core.c

+2 −1
Original line number Diff line number Diff line
@@ -1900,7 +1900,8 @@ static inline void set_window_start(struct rq *rq) 
	int cpu = cpu_of(rq);

	struct rq *sync_rq = cpu_rq(sync_cpu);



	if (rq->window_start || !sched_enable_hmp)

	if (rq->window_start || !sched_enable_hmp ||

	    !sched_clock_initialized() || !sched_clock_cpu(cpu))

		return;



	if (cpu == sync_cpu) {

kernel/time/sched_clock.c

+8 −0
Original line number Diff line number Diff line
@@ -32,6 +32,7 @@ struct clock_data { 


static struct hrtimer sched_clock_timer;

static int irqtime = -1;

static int initialized;



core_param(irqtime, irqtime, int, 0400);
@@ -178,6 +179,11 @@ unsigned long long notrace sched_clock(void) 
	return sched_clock_func();

}



int sched_clock_initialized(void)

{

	return initialized;

}



void __init sched_clock_postinit(void)

{

	/*
@@ -196,6 +202,8 @@ void __init sched_clock_postinit(void) 
	hrtimer_init(&sched_clock_timer, CLOCK_MONOTONIC, HRTIMER_MODE_REL);

	sched_clock_timer.function = sched_clock_poll;

	hrtimer_start(&sched_clock_timer, cd.wrap_kt, HRTIMER_MODE_REL);



	initialized = 1;

}



static int sched_clock_suspend(void)