diff options
author | Jeff Garzik <jgarzik@pobox.com> | 2006-02-20 02:16:23 -0500 |
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committer | Jeff Garzik <jgarzik@pobox.com> | 2006-02-20 02:16:23 -0500 |
commit | 5b2ffed906a3ebd4e52a5bbef06b99a517c53e4b (patch) | |
tree | 2f900f89d93db6b0822d8bdf4f49851c581c12a6 /arch/ia64/kernel/time.c | |
parent | f1b318793dcd2d9ff6b5ac06e7762098fa079cee (diff) | |
parent | bd71c2b17468a2531fb4c81ec1d73520845e97e1 (diff) |
Merge branch 'master'
Diffstat (limited to 'arch/ia64/kernel/time.c')
-rw-r--r-- | arch/ia64/kernel/time.c | 39 |
1 files changed, 17 insertions, 22 deletions
diff --git a/arch/ia64/kernel/time.c b/arch/ia64/kernel/time.c index a094ec49ccf..307d01e15b2 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); |