diff options
Diffstat (limited to 'include/linux')
| -rw-r--r-- | include/linux/time.h | 31 |
1 files changed, 31 insertions, 0 deletions
diff --git a/include/linux/time.h b/include/linux/time.h index b85d596949a3..9a92850cab4b 100644 --- a/include/linux/time.h +++ b/include/linux/time.h @@ -177,6 +177,37 @@ struct timezone { (SH_DIV((MAX_JIFFY_OFFSET >> SEC_JIFFIE_SC) * TICK_NSEC, NSEC_PER_SEC, 1) - 1) #endif + +/* + * Convert jiffies to milliseconds and back. + * + * Avoid unnecessary multiplications/divisions in the + * two most common HZ cases: + */ +static inline unsigned int jiffies_to_msecs(unsigned long j) +{ +#if HZ <= 1000 && !(1000 % HZ) + return (1000 / HZ) * j; +#elif HZ > 1000 && !(HZ % 1000) + return (j + (HZ / 1000) - 1)/(HZ / 1000); +#else + return (j * 1000) / HZ; +#endif +} +static inline unsigned long msecs_to_jiffies(unsigned int m) +{ +#if HZ <= 1000 && !(1000 % HZ) + return (m + (1000 / HZ) - 1) / (1000 / HZ); +#elif HZ > 1000 && !(HZ % 1000) + return m * (HZ / 1000); +#else + return (m * HZ + 999) / 1000; +#endif +} + +#define JIFFIES_TO_MSECS(j) jiffies_to_msecs(j) +#define MSECS_TO_JIFFIES(m) msecs_to_jiffies(m) + /* * The TICK_NSEC - 1 rounds up the value to the next resolution. Note * that a remainder subtract here would not do the right thing as the |