redonkable/remarkable-linux
redonkable/remarkable-linux
1
0
Fork 0
Code Releases Activity

sched/clock: Remove local_irq_disable() from the clocks

Browse source 
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: Peter 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: Ingo Molnar <mingo@kernel.org>
This commit is contained in:
Peter Zijlstra 2013-11-28 19:31:23 +01:00 committed by Ingo Molnar
parent 20d1c86a57
commit ef08f0fff8
1 changed files with 6 additions and 28 deletions
Show stats Download patch file Download diff file Expand all files Collapse all files

34
kernel/sched/clock.c
View file

@ -26,9 +26,10 @@
* at 0 on boot (but people really shouldn't rely on that).
*
* 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.
*
* sched_clock_cpu(i)
*
* How:
*
* The implementation either uses sched_clock() when
@ -50,15 +51,6 @@
* Furthermore, explicit sleep and wakeup hooks allow us to account for time
* 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/hardirq.h>
@ -242,20 +234,20 @@ u64 sched_clock_cpu(int cpu)
struct sched_clock_data *scd;
u64 clock;
WARN_ON_ONCE(!irqs_disabled());
if (sched_clock_stable)
return sched_clock();
if (unlikely(!sched_clock_running))
return 0ull;
preempt_disable();
scd = cpu_sdc(cpu);
if (cpu != smp_processor_id())
clock = sched_clock_remote(scd);
else
clock = sched_clock_local(scd);
preempt_enable();
return clock;
}
@ -316,14 +308,7 @@ EXPORT_SYMBOL_GPL(sched_clock_idle_wakeup_event);
*/
u64 cpu_clock(int cpu)
{
u64 clock;
unsigned long flags;
local_irq_save(flags);
clock = sched_clock_cpu(cpu);
local_irq_restore(flags);
return clock;
return sched_clock_cpu(cpu);
}
/*
@ -335,14 +320,7 @@ u64 cpu_clock(int cpu)
*/
u64 local_clock(void)
{
u64 clock;
unsigned long flags;
local_irq_save(flags);
clock = sched_clock_cpu(smp_processor_id());
local_irq_restore(flags);
return clock;
return sched_clock_cpu(raw_smp_processor_id());
}
#else /* CONFIG_HAVE_UNSTABLE_SCHED_CLOCK */