[PATCH] sched: generalize CONFIG_IRQ_TIME_ACCOUNTING for X86 and ARM
From: peterz@infradead.org (Peter Zijlstra)
Date: 2012-02-27 10:12:31
Also in:
lkml
On Mon, 2012-02-20 at 10:04 +0400, Dmitry Antipov wrote:
Generalize CONFIG_IRQ_TIME_ACCOUNTING between X86 and ARM, move "noirqtime=" option to common debugging code. For a bit of backward compatibility, X86-specific option "tsc=noirqtime" is preserved, but issues a warning. Suggested-by: Yong Zhang <redacted> Suggested-by: Russell King <redacted> Suggested-by: Ingo Molnar <redacted> Acked-by: Venkatesh Pallipadi <redacted> Signed-off-by: Dmitry Antipov <redacted>
Thanks for Cc'ing me (maintainer) and Venki (original author of the stuff) :-)
quoted hunk ↗ jump to hunk
diff --git a/include/linux/sched.h b/include/linux/sched.h index 7d379a6..9b13f79 100644 --- a/include/linux/sched.h +++ b/include/linux/sched.h@@ -1961,13 +1961,16 @@ extern void sched_clock_idle_wakeup_event(u64 delta_ns); #endif #ifdef CONFIG_IRQ_TIME_ACCOUNTING -/* - * An i/f to runtime opt-in for irq time accounting based off of sched_clock. - * The reason for this explicit opt-in is not to have perf penalty with - * slow sched_clocks. - */ -extern void enable_sched_clock_irqtime(void); -extern void disable_sched_clock_irqtime(void); +extern int sched_clock_irqtime; +static inline void enable_sched_clock_irqtime(void) +{ + if (sched_clock_irqtime == -1) + sched_clock_irqtime = 1; +} +static inline void disable_sched_clock_irqtime(void) +{ + sched_clock_irqtime = 0; +} #else static inline void enable_sched_clock_irqtime(void) {} static inline void disable_sched_clock_irqtime(void) {}
Please keep them out-of-line, its not a fast path and it avoids having to expose the state variable.
quoted hunk ↗ jump to hunk
diff --git a/kernel/sched/core.c b/kernel/sched/core.c index 5255c9d..4e7a197 100644 --- a/kernel/sched/core.c +++ b/kernel/sched/core.c@@ -757,18 +757,21 @@ static DEFINE_PER_CPU(u64, cpu_hardirq_time); static DEFINE_PER_CPU(u64, cpu_softirq_time); static DEFINE_PER_CPU(u64, irq_start_time); -static int sched_clock_irqtime; -void enable_sched_clock_irqtime(void) -{ - sched_clock_irqtime = 1; -} +/* + * -1 if not initialized, 0 if disabled with "noirqtime" kernel option + * or after unstable clock was detected, 1 if enabled and active. + */
You forgot to explain what you need the tri-state for.
+__read_mostly int sched_clock_irqtime = -1;
-void disable_sched_clock_irqtime(void)
+static int __init irqtime_setup(char *str)
{
sched_clock_irqtime = 0;
+ return 1;
}
+__setup("noirqtime", irqtime_setup);
+
#ifndef CONFIG_64BIT
static DEFINE_PER_CPU(seqcount_t, irq_time_seq);Other than that no real objections.. I guess.