Messages in this thread Patch in this message | | | Subject | Re: Fwd: Commit 76a2a6ee8a0660a29127f05989ac59ae1ce865fa breaks PXA270 (at least)? | From | Peter Zijlstra <> | Date | Thu, 31 Jul 2008 23:47:55 +0200 |
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On Thu, 2008-07-31 at 23:37 +0200, Ingo Molnar wrote: > * Andrew Morton <akpm@linux-foundation.org> wrote: > > > On Tue, 29 Jul 2008 23:31:05 +0100 > > Russell King - ARM Linux <linux@arm.linux.org.uk> wrote: > > > > > But then some bright spark thought it would be a good idea to get > > > rid of printk_clock(). > > > > <does git-log, searches for printk_clock> > > i think this is a fresh regression via the introduction of > kernel/sched_clock.c. We lost the (known) early-init behavior of > cpu_clock() in the !UNSTABLE_SCHED_CLOCK case. The fix would be to > restore that, not to reintroduce printk_clock(). > > Peter, any ideas?
How about something like this, it builds an atificial delay, exactly like we already have for the HAVE_UNSTABLE_SCHED_CLOCK case.
This keeps cpu_clock() 0 until after sched_clock_init().
Russell, Bill, is this sufficient?
Signed-off-by: Peter Zijlstra <a.p.zijlstra@chello.nl> --- diff --git a/include/linux/sched.h b/include/linux/sched.h index 1b26ed2..d13264b 100644 --- a/include/linux/sched.h +++ b/include/linux/sched.h @@ -1550,16 +1550,10 @@ static inline int set_cpus_allowed(struct task_struct *p, cpumask_t new_mask) extern unsigned long long sched_clock(void); -#ifndef CONFIG_HAVE_UNSTABLE_SCHED_CLOCK -static inline void sched_clock_init(void) -{ -} - -static inline u64 sched_clock_cpu(int cpu) -{ - return sched_clock(); -} +extern void sched_clock_init(void); +extern u64 sched_clock_cpu(int cpu); +#ifndef CONFIG_HAVE_UNSTABLE_SCHED_CLOCK static inline void sched_clock_tick(void) { } @@ -1583,8 +1577,6 @@ static inline void sched_clock_tick_start(int cpu) #endif #else /* CONFIG_HAVE_UNSTABLE_SCHED_CLOCK */ -extern void sched_clock_init(void); -extern u64 sched_clock_cpu(int cpu); extern void sched_clock_tick(void); extern void sched_clock_idle_sleep_event(void); extern void sched_clock_idle_wakeup_event(u64 delta_ns); diff --git a/kernel/sched_clock.c b/kernel/sched_clock.c index 22ed55d..a804582 100644 --- a/kernel/sched_clock.c +++ b/kernel/sched_clock.c @@ -32,6 +32,7 @@ #include <linux/ktime.h> #include <linux/module.h> +static __read_mostly int sched_clock_running; #ifdef CONFIG_HAVE_UNSTABLE_SCHED_CLOCK @@ -71,8 +72,6 @@ static inline struct sched_clock_data *cpu_sdc(int cpu) return &per_cpu(sched_clock_data, cpu); } -static __read_mostly int sched_clock_running; - void sched_clock_init(void) { u64 ktime_now = ktime_to_ns(ktime_get()); @@ -319,6 +318,21 @@ void sched_clock_idle_wakeup_event(u64 delta_ns) } EXPORT_SYMBOL_GPL(sched_clock_idle_wakeup_event); +#else /* CONFIG_HAVE_UNSTABLE_SCHED_CLOCK */ + +void sched_clock_init(void) +{ + sched_clock_running = 1; +} + +u64 sched_clock_cpu(int cpu) +{ + if (unlikely(!sched_clock_running)) + return 0; + + return sched_clock(); +} + #endif /*
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