On Mon, 2008-08-04 at 12:46 -0700, Nishanth Aravamudan wrote: > Bisection on an x455 (2-node IA64) showed that commit > 27ec4407790d075c325e1f4da0a19c56953cce23 (sched: make cpu_clock() > globally synchronous) broke booting. I see the uncompressing initramfs > message and then nothing on the console. I wait about 5 minutes (which > is way longer than it takes for the first console messages to get > printed normally). The commit immediately before it works fine. > > The commit no longer cleanly reverts, but I tried to manually put things > back to the way they were before in cpu_clock(). The resulting kernel > boots fine. I could figure out a clean way to leave cpu_clock() in > sched_clock.c because of all the rq dependencies from sched.c. The > attempt I tested is below [1]. This patch is *NOT* for inclusion, just > to demonstrate what I tested. > > I'm happy to test any better patches. Does this work for you? --- Subject: sched_clock: delay using sched_clock() Some arch's can't handle sched_clock() being called too early - delay this until sched_clock_init() has been called. Reported-by: Bill Gatliff <bgat@xxxxxxxxxxxxxxx> Signed-off-by: Peter Zijlstra <a.p.zijlstra@xxxxxxxxx> CC: Russell King - ARM Linux <linux@xxxxxxxxxxxxxxxx> --- include/linux/sched.h | 14 +++----------- kernel/sched_clock.c | 18 ++++++++++++++++-- 2 files changed, 19 insertions(+), 13 deletions(-) Index: linux-2.6/include/linux/sched.h =================================================================== --- linux-2.6.orig/include/linux/sched.h +++ linux-2.6/include/linux/sched.h @@ -1551,16 +1551,10 @@ static inline int set_cpus_allowed(struc 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) { } @@ -1584,8 +1578,6 @@ static inline void sched_clock_tick_star #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); Index: linux-2.6/kernel/sched_clock.c =================================================================== --- linux-2.6.orig/kernel/sched_clock.c +++ linux-2.6/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 *c 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 d } 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 /* -- To unsubscribe from this list: send the line "unsubscribe linux-ia64" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
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