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Commit ef08f0ff authored by Peter Zijlstra's avatar Peter Zijlstra Committed by Ingo Molnar
Browse files

sched/clock: Remove local_irq_disable() from the clocks 



Now that x86 no longer requires IRQs disabled for sched_clock() and
ia64 never had this requirement (it doesn't seem to do cpufreq at
all), we can remove the requirement of disabling IRQs.

                        MAINLINE   PRE        POST

    sched_clock_stable: 1          1          1
    (cold) sched_clock: 329841     257223     221876
    (cold) local_clock: 301773     309889     234692
    (warm) sched_clock: 38375      25280      25602
    (warm) local_clock: 100371     85268      33265
    (warm) rdtsc:       27340      24247      24214
    sched_clock_stable: 0          0          0
    (cold) sched_clock: 382634     301224     235941
    (cold) local_clock: 396890     399870     297017
    (warm) sched_clock: 38194      25630      25233
    (warm) local_clock: 143452     129629     71234
    (warm) rdtsc:       27345      24307      24245

Signed-off-by: default avatarPeter Zijlstra <peterz@infradead.org>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Andrew Morton <akpm@linux-foundation.org>
Link: http://lkml.kernel.org/n/tip-36e5kohiasnr106d077mgubp@git.kernel.org


Signed-off-by: default avatarIngo Molnar <mingo@kernel.org>
parent 20d1c86a

kernel/sched/clock.c

+6 −28
Original line number Original line Diff line number Diff line
@@ -26,9 +26,10 @@ 
 * at 0 on boot (but people really shouldn't rely on that).

 * at 0 on boot (but people really shouldn't rely on that).

 *

 *

 * cpu_clock(i)       -- can be used from any context, including NMI.

 * cpu_clock(i)       -- can be used from any context, including NMI.

 * sched_clock_cpu(i) -- must be used with local IRQs disabled (implied by NMI)

 * local_clock()      -- is cpu_clock() on the current cpu.

 * local_clock()      -- is cpu_clock() on the current cpu.

 *

 *

 * sched_clock_cpu(i)

 *

 * How:

 * How:

 *

 *

 * The implementation either uses sched_clock() when

 * The implementation either uses sched_clock() when
@@ -50,15 +51,6 @@ 
 * Furthermore, explicit sleep and wakeup hooks allow us to account for time

 * Furthermore, explicit sleep and wakeup hooks allow us to account for time

 * that is otherwise invisible (TSC gets stopped).

 * that is otherwise invisible (TSC gets stopped).

 *

 *

 *

 * Notes:

 *

 * The !IRQ-safetly of sched_clock() and sched_clock_cpu() comes from things

 * like cpufreq interrupts that can change the base clock (TSC) multiplier

 * and cause funny jumps in time -- although the filtering provided by

 * sched_clock_cpu() should mitigate serious artifacts we cannot rely on it

 * in general since for !CONFIG_HAVE_UNSTABLE_SCHED_CLOCK we fully rely on

 * sched_clock().

 */

 */

#include <linux/spinlock.h>

#include <linux/spinlock.h>

#include <linux/hardirq.h>

#include <linux/hardirq.h>
@@ -242,20 +234,20 @@ u64 sched_clock_cpu(int cpu) 
	struct sched_clock_data *scd;

	struct sched_clock_data *scd;

	u64 clock;

	u64 clock;





	WARN_ON_ONCE(!irqs_disabled());



	if (sched_clock_stable)

	if (sched_clock_stable)

		return sched_clock();

		return sched_clock();





	if (unlikely(!sched_clock_running))

	if (unlikely(!sched_clock_running))

		return 0ull;

		return 0ull;





	preempt_disable();

	scd = cpu_sdc(cpu);

	scd = cpu_sdc(cpu);





	if (cpu != smp_processor_id())

	if (cpu != smp_processor_id())

		clock = sched_clock_remote(scd);

		clock = sched_clock_remote(scd);

	else

	else

		clock = sched_clock_local(scd);

		clock = sched_clock_local(scd);

	preempt_enable();





	return clock;

	return clock;

}

}
@@ -316,14 +308,7 @@ EXPORT_SYMBOL_GPL(sched_clock_idle_wakeup_event); 
 */

 */

u64 cpu_clock(int cpu)

u64 cpu_clock(int cpu)

{

{

	u64 clock;

	return sched_clock_cpu(cpu);

	unsigned long flags;



	local_irq_save(flags);

	clock = sched_clock_cpu(cpu);

	local_irq_restore(flags);



	return clock;

}

}





/*

/*
@@ -335,14 +320,7 @@ u64 cpu_clock(int cpu) 
 */

 */

u64 local_clock(void)

u64 local_clock(void)

{

{

	u64 clock;

	return sched_clock_cpu(raw_smp_processor_id());

	unsigned long flags;



	local_irq_save(flags);

	clock = sched_clock_cpu(smp_processor_id());

	local_irq_restore(flags);



	return clock;

}

}





#else /* CONFIG_HAVE_UNSTABLE_SCHED_CLOCK */

#else /* CONFIG_HAVE_UNSTABLE_SCHED_CLOCK */