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: 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>
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@ -26,9 +26,10 @@
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* at 0 on boot (but people really shouldn't rely on that).
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*
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* cpu_clock(i) -- can be used from any context, including NMI.
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* sched_clock_cpu(i) -- must be used with local IRQs disabled (implied by NMI)
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* local_clock() -- is cpu_clock() on the current cpu.
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*
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* sched_clock_cpu(i)
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*
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* How:
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*
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* The implementation either uses sched_clock() when
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@ -50,15 +51,6 @@
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* Furthermore, explicit sleep and wakeup hooks allow us to account for time
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* that is otherwise invisible (TSC gets stopped).
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*
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*
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* Notes:
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*
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* The !IRQ-safetly of sched_clock() and sched_clock_cpu() comes from things
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* like cpufreq interrupts that can change the base clock (TSC) multiplier
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* and cause funny jumps in time -- although the filtering provided by
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* sched_clock_cpu() should mitigate serious artifacts we cannot rely on it
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* in general since for !CONFIG_HAVE_UNSTABLE_SCHED_CLOCK we fully rely on
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* sched_clock().
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*/
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#include <linux/spinlock.h>
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#include <linux/hardirq.h>
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@ -242,20 +234,20 @@ u64 sched_clock_cpu(int cpu)
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struct sched_clock_data *scd;
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u64 clock;
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WARN_ON_ONCE(!irqs_disabled());
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if (sched_clock_stable)
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return sched_clock();
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if (unlikely(!sched_clock_running))
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return 0ull;
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preempt_disable();
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scd = cpu_sdc(cpu);
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if (cpu != smp_processor_id())
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clock = sched_clock_remote(scd);
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else
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clock = sched_clock_local(scd);
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preempt_enable();
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return clock;
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}
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@ -316,14 +308,7 @@ EXPORT_SYMBOL_GPL(sched_clock_idle_wakeup_event);
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*/
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u64 cpu_clock(int cpu)
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{
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u64 clock;
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unsigned long flags;
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local_irq_save(flags);
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clock = sched_clock_cpu(cpu);
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local_irq_restore(flags);
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return clock;
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return sched_clock_cpu(cpu);
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}
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/*
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@ -335,14 +320,7 @@ u64 cpu_clock(int cpu)
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*/
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u64 local_clock(void)
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{
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u64 clock;
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unsigned long flags;
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local_irq_save(flags);
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clock = sched_clock_cpu(smp_processor_id());
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local_irq_restore(flags);
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return clock;
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return sched_clock_cpu(raw_smp_processor_id());
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}
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#else /* CONFIG_HAVE_UNSTABLE_SCHED_CLOCK */
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