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Commit 5d2a4e91 authored by Pavel Tatashin's avatar Pavel Tatashin Committed by Thomas Gleixner
Browse files

sched/clock: Move sched clock initialization and merge with generic clock 



sched_clock_postinit() initializes a generic clock on systems where no
other clock is provided. This function may be called only after
timekeeping_init().

Rename sched_clock_postinit to generic_clock_inti() and call it from
sched_clock_init(). Move the call for sched_clock_init() until after
time_init().

Suggested-by: default avatarPeter Zijlstra <peterz@infradead.org>
Signed-off-by: default avatarPavel Tatashin <pasha.tatashin@oracle.com>
Signed-off-by: default avatarThomas Gleixner <tglx@linutronix.de>
Cc: steven.sistare@oracle.com
Cc: daniel.m.jordan@oracle.com
Cc: linux@armlinux.org.uk
Cc: schwidefsky@de.ibm.com
Cc: heiko.carstens@de.ibm.com
Cc: john.stultz@linaro.org
Cc: sboyd@codeaurora.org
Cc: hpa@zytor.com
Cc: douly.fnst@cn.fujitsu.com
Cc: prarit@redhat.com
Cc: feng.tang@intel.com
Cc: pmladek@suse.com
Cc: gnomes@lxorguk.ukuu.org.uk
Cc: linux-s390@vger.kernel.org
Cc: boris.ostrovsky@oracle.com
Cc: jgross@suse.com
Cc: pbonzini@redhat.com
Link: https://lkml.kernel.org/r/20180719205545.16512-23-pasha.tatashin@oracle.com
parent 4763f03d

include/linux/sched_clock.h

+2 −3
Original line number Diff line number Diff line
@@ -9,17 +9,16 @@ 
#define LINUX_SCHED_CLOCK



#ifdef CONFIG_GENERIC_SCHED_CLOCK

extern void sched_clock_postinit(void);

extern void generic_sched_clock_init(void);



extern void sched_clock_register(u64 (*read)(void), int bits,

				 unsigned long rate);

#else

static inline void sched_clock_postinit(void) { }

static inline void generic_sched_clock_init(void) { }



static inline void sched_clock_register(u64 (*read)(void), int bits,

					unsigned long rate)

{

	;

}

#endif

init/main.c

+2 −2
Original line number Diff line number Diff line
@@ -79,7 +79,7 @@ 
#include <linux/pti.h>

#include <linux/blkdev.h>

#include <linux/elevator.h>

#include <linux/sched_clock.h>

#include <linux/sched/clock.h>

#include <linux/sched/task.h>

#include <linux/sched/task_stack.h>

#include <linux/context_tracking.h>
@@ -642,7 +642,7 @@ asmlinkage __visible void __init start_kernel(void) 
	softirq_init();

	timekeeping_init();

	time_init();

	sched_clock_postinit();

	sched_clock_init();

	printk_safe_init();

	perf_event_init();

	profile_init();

kernel/sched/clock.c

+17 −10
Original line number Diff line number Diff line
@@ -53,6 +53,7 @@ 
 *

 */

#include "sched.h"

#include <linux/sched_clock.h>



/*

 * Scheduler clock - returns current time in nanosec units.
@@ -68,11 +69,6 @@ EXPORT_SYMBOL_GPL(sched_clock); 


__read_mostly int sched_clock_running;



void sched_clock_init(void)

{

	sched_clock_running = 1;

}



#ifdef CONFIG_HAVE_UNSTABLE_SCHED_CLOCK

/*

 * We must start with !__sched_clock_stable because the unstable -> stable
@@ -199,6 +195,15 @@ void clear_sched_clock_stable(void) 
		__clear_sched_clock_stable();

}



static void __sched_clock_gtod_offset(void)

{

	__gtod_offset = (sched_clock() + __sched_clock_offset) - ktime_get_ns();

}



void __init sched_clock_init(void)

{

	sched_clock_running = 1;

}

/*

 * We run this as late_initcall() such that it runs after all built-in drivers,

 * notably: acpi_processor and intel_idle, which can mark the TSC as unstable.
@@ -385,8 +390,6 @@ void sched_clock_tick(void) 


void sched_clock_tick_stable(void)

{

	u64 gtod, clock;



	if (!sched_clock_stable())

		return;
@@ -398,9 +401,7 @@ void sched_clock_tick_stable(void) 
	 * TSC to be unstable, any computation will be computing crap.

	 */

	local_irq_disable();

	gtod = ktime_get_ns();

	clock = sched_clock();

	__gtod_offset = (clock + __sched_clock_offset) - gtod;

	__sched_clock_gtod_offset();

	local_irq_enable();

}
@@ -434,6 +435,12 @@ EXPORT_SYMBOL_GPL(sched_clock_idle_wakeup_event); 


#else /* CONFIG_HAVE_UNSTABLE_SCHED_CLOCK */



void __init sched_clock_init(void)

{

	sched_clock_running = 1;

	generic_sched_clock_init();

}



u64 sched_clock_cpu(int cpu)

{

	if (unlikely(!sched_clock_running))

kernel/sched/core.c

+0 −1
Original line number Diff line number Diff line
@@ -5954,7 +5954,6 @@ void __init sched_init(void) 
	int i, j;

	unsigned long alloc_size = 0, ptr;



	sched_clock_init();

	wait_bit_init();



#ifdef CONFIG_FAIR_GROUP_SCHED

kernel/time/sched_clock.c

+1 −1
Original line number Diff line number Diff line
@@ -237,7 +237,7 @@ sched_clock_register(u64 (*read)(void), int bits, unsigned long rate) 
	pr_debug("Registered %pF as sched_clock source\n", read);

}



void __init sched_clock_postinit(void)

void __init generic_sched_clock_init(void)

{

	/*

	 * If no sched_clock() function has been provided at that point,