diff options
Diffstat (limited to 'kernel/time/jiffies.c')
| -rw-r--r-- | kernel/time/jiffies.c | 38 |
1 files changed, 10 insertions, 28 deletions
diff --git a/kernel/time/jiffies.c b/kernel/time/jiffies.c index a5cffe2a1770..bc4db9e5ab70 100644 --- a/kernel/time/jiffies.c +++ b/kernel/time/jiffies.c @@ -10,28 +10,9 @@ #include <linux/init.h> #include "timekeeping.h" +#include "tick-internal.h" -/* Since jiffies uses a simple TICK_NSEC multiplier - * conversion, the .shift value could be zero. However - * this would make NTP adjustments impossible as they are - * in units of 1/2^.shift. Thus we use JIFFIES_SHIFT to - * shift both the nominator and denominator the same - * amount, and give ntp adjustments in units of 1/2^8 - * - * The value 8 is somewhat carefully chosen, as anything - * larger can result in overflows. TICK_NSEC grows as HZ - * shrinks, so values greater than 8 overflow 32bits when - * HZ=100. - */ -#if HZ < 34 -#define JIFFIES_SHIFT 6 -#elif HZ < 67 -#define JIFFIES_SHIFT 7 -#else -#define JIFFIES_SHIFT 8 -#endif - static u64 jiffies_read(struct clocksource *cs) { return (u64) jiffies; @@ -44,18 +25,19 @@ static u64 jiffies_read(struct clocksource *cs) * the timer interrupt frequency HZ and it suffers * inaccuracies caused by missed or lost timer * interrupts and the inability for the timer - * interrupt hardware to accuratly tick at the + * interrupt hardware to accurately tick at the * requested HZ value. It is also not recommended * for "tick-less" systems. */ static struct clocksource clocksource_jiffies = { - .name = "jiffies", - .rating = 1, /* lowest valid rating*/ - .read = jiffies_read, - .mask = CLOCKSOURCE_MASK(32), - .mult = TICK_NSEC << JIFFIES_SHIFT, /* details above */ - .shift = JIFFIES_SHIFT, - .max_cycles = 10, + .name = "jiffies", + .rating = 1, /* lowest valid rating*/ + .uncertainty_margin = 32 * NSEC_PER_MSEC, + .read = jiffies_read, + .mask = CLOCKSOURCE_MASK(32), + .mult = TICK_NSEC << JIFFIES_SHIFT, /* details above */ + .shift = JIFFIES_SHIFT, + .max_cycles = 10, }; __cacheline_aligned_in_smp DEFINE_RAW_SPINLOCK(jiffies_lock); |