diff options
| -rw-r--r-- | arch/ia64/kernel/time.c | 39 | ||||
| -rw-r--r-- | arch/ia64/sn/kernel/sn2/timer.c | 19 | ||||
| -rw-r--r-- | include/asm-ia64/timex.h | 2 |
3 files changed, 38 insertions, 22 deletions
diff --git a/arch/ia64/kernel/time.c b/arch/ia64/kernel/time.c index a094ec4..307d01e 100644 --- a/arch/ia64/kernel/time.c +++ b/arch/ia64/kernel/time.c @@ -250,32 +250,27 @@ time_init (void) set_normalized_timespec(&wall_to_monotonic, -xtime.tv_sec, -xtime.tv_nsec); } -#define SMALLUSECS 100 - -void -udelay (unsigned long usecs) +/* + * Generic udelay assumes that if preemption is allowed and the thread + * migrates to another CPU, that the ITC values are synchronized across + * all CPUs. + */ +static void +ia64_itc_udelay (unsigned long usecs) { - unsigned long start; - unsigned long cycles; - unsigned long smallusecs; + unsigned long start = ia64_get_itc(); + unsigned long end = start + usecs*local_cpu_data->cyc_per_usec; - /* - * Execute the non-preemptible delay loop (because the ITC might - * not be synchronized between CPUS) in relatively short time - * chunks, allowing preemption between the chunks. - */ - while (usecs > 0) { - smallusecs = (usecs > SMALLUSECS) ? SMALLUSECS : usecs; - preempt_disable(); - cycles = smallusecs*local_cpu_data->cyc_per_usec; - start = ia64_get_itc(); + while (time_before(ia64_get_itc(), end)) + cpu_relax(); +} - while (ia64_get_itc() - start < cycles) - cpu_relax(); +void (*ia64_udelay)(unsigned long usecs) = &ia64_itc_udelay; - preempt_enable(); - usecs -= smallusecs; - } +void +udelay (unsigned long usecs) +{ + (*ia64_udelay)(usecs); } EXPORT_SYMBOL(udelay); diff --git a/arch/ia64/sn/kernel/sn2/timer.c b/arch/ia64/sn/kernel/sn2/timer.c index deb9baf..56a88b6 100644 --- a/arch/ia64/sn/kernel/sn2/timer.c +++ b/arch/ia64/sn/kernel/sn2/timer.c @@ -14,6 +14,7 @@ #include <asm/hw_irq.h> #include <asm/system.h> +#include <asm/timex.h> #include <asm/sn/leds.h> #include <asm/sn/shub_mmr.h> @@ -28,9 +29,27 @@ static struct time_interpolator sn2_interpolator = { .source = TIME_SOURCE_MMIO64 }; +/* + * sn udelay uses the RTC instead of the ITC because the ITC is not + * synchronized across all CPUs, and the thread may migrate to another CPU + * if preemption is enabled. + */ +static void +ia64_sn_udelay (unsigned long usecs) +{ + unsigned long start = rtc_time(); + unsigned long end = start + + usecs * sn_rtc_cycles_per_second / 1000000; + + while (time_before((unsigned long)rtc_time(), end)) + cpu_relax(); +} + void __init sn_timer_init(void) { sn2_interpolator.frequency = sn_rtc_cycles_per_second; sn2_interpolator.addr = RTC_COUNTER_ADDR; register_time_interpolator(&sn2_interpolator); + + ia64_udelay = &ia64_sn_udelay; } diff --git a/include/asm-ia64/timex.h b/include/asm-ia64/timex.h index 414aae0..05a6baf 100644 --- a/include/asm-ia64/timex.h +++ b/include/asm-ia64/timex.h @@ -15,6 +15,8 @@ typedef unsigned long cycles_t; +extern void (*ia64_udelay)(unsigned long usecs); + /* * For performance reasons, we don't want to define CLOCK_TICK_TRATE as * local_cpu_data->itc_rate. Fortunately, we don't have to, either: according to George |