diff options
Diffstat (limited to 'include/linux/jiffies.h')
| -rw-r--r-- | include/linux/jiffies.h | 222 |
1 files changed, 19 insertions, 203 deletions
diff --git a/include/linux/jiffies.h b/include/linux/jiffies.h index 0ec6e28bccd..c080f61fb02 100644 --- a/include/linux/jiffies.h +++ b/include/linux/jiffies.h @@ -142,13 +142,13 @@ static inline u64 get_jiffies_64(void) * * And some not so obvious. * - * Note that we don't want to return MAX_LONG, because + * Note that we don't want to return LONG_MAX, because * for various timeout reasons we often end up having * to wait "jiffies+1" in order to guarantee that we wait * at _least_ "jiffies" - so "jiffies+1" had better still * be positive. */ -#define MAX_JIFFY_OFFSET ((~0UL >> 1)-1) +#define MAX_JIFFY_OFFSET ((LONG_MAX >> 1)-1) /* * We want to do realistic conversions of time so we need to use the same @@ -259,207 +259,23 @@ static inline u64 get_jiffies_64(void) #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(const unsigned long j) -{ -#if HZ <= MSEC_PER_SEC && !(MSEC_PER_SEC % HZ) - return (MSEC_PER_SEC / HZ) * j; -#elif HZ > MSEC_PER_SEC && !(HZ % MSEC_PER_SEC) - return (j + (HZ / MSEC_PER_SEC) - 1)/(HZ / MSEC_PER_SEC); -#else - return (j * MSEC_PER_SEC) / HZ; -#endif -} - -static inline unsigned int jiffies_to_usecs(const unsigned long j) -{ -#if HZ <= USEC_PER_SEC && !(USEC_PER_SEC % HZ) - return (USEC_PER_SEC / HZ) * j; -#elif HZ > USEC_PER_SEC && !(HZ % USEC_PER_SEC) - return (j + (HZ / USEC_PER_SEC) - 1)/(HZ / USEC_PER_SEC); -#else - return (j * USEC_PER_SEC) / HZ; -#endif -} - -static inline unsigned long msecs_to_jiffies(const unsigned int m) -{ - if (m > jiffies_to_msecs(MAX_JIFFY_OFFSET)) - return MAX_JIFFY_OFFSET; -#if HZ <= MSEC_PER_SEC && !(MSEC_PER_SEC % HZ) - return (m + (MSEC_PER_SEC / HZ) - 1) / (MSEC_PER_SEC / HZ); -#elif HZ > MSEC_PER_SEC && !(HZ % MSEC_PER_SEC) - return m * (HZ / MSEC_PER_SEC); -#else - return (m * HZ + MSEC_PER_SEC - 1) / MSEC_PER_SEC; -#endif -} - -static inline unsigned long usecs_to_jiffies(const unsigned int u) -{ - if (u > jiffies_to_usecs(MAX_JIFFY_OFFSET)) - return MAX_JIFFY_OFFSET; -#if HZ <= USEC_PER_SEC && !(USEC_PER_SEC % HZ) - return (u + (USEC_PER_SEC / HZ) - 1) / (USEC_PER_SEC / HZ); -#elif HZ > USEC_PER_SEC && !(HZ % USEC_PER_SEC) - return u * (HZ / USEC_PER_SEC); -#else - return (u * HZ + USEC_PER_SEC - 1) / USEC_PER_SEC; -#endif -} - -/* - * 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 - * resolution values don't fall on second boundries. I.e. the line: - * nsec -= nsec % TICK_NSEC; is NOT a correct resolution rounding. - * - * Rather, we just shift the bits off the right. - * - * The >> (NSEC_JIFFIE_SC - SEC_JIFFIE_SC) converts the scaled nsec - * value to a scaled second value. - */ -static __inline__ unsigned long -timespec_to_jiffies(const struct timespec *value) -{ - unsigned long sec = value->tv_sec; - long nsec = value->tv_nsec + TICK_NSEC - 1; - - if (sec >= MAX_SEC_IN_JIFFIES){ - sec = MAX_SEC_IN_JIFFIES; - nsec = 0; - } - return (((u64)sec * SEC_CONVERSION) + - (((u64)nsec * NSEC_CONVERSION) >> - (NSEC_JIFFIE_SC - SEC_JIFFIE_SC))) >> SEC_JIFFIE_SC; - -} - -static __inline__ void -jiffies_to_timespec(const unsigned long jiffies, struct timespec *value) -{ - /* - * Convert jiffies to nanoseconds and separate with - * one divide. - */ - u64 nsec = (u64)jiffies * TICK_NSEC; - value->tv_sec = div_long_long_rem(nsec, NSEC_PER_SEC, &value->tv_nsec); -} - -/* Same for "timeval" - * - * Well, almost. The problem here is that the real system resolution is - * in nanoseconds and the value being converted is in micro seconds. - * Also for some machines (those that use HZ = 1024, in-particular), - * there is a LARGE error in the tick size in microseconds. - - * The solution we use is to do the rounding AFTER we convert the - * microsecond part. Thus the USEC_ROUND, the bits to be shifted off. - * Instruction wise, this should cost only an additional add with carry - * instruction above the way it was done above. - */ -static __inline__ unsigned long -timeval_to_jiffies(const struct timeval *value) -{ - unsigned long sec = value->tv_sec; - long usec = value->tv_usec; - - if (sec >= MAX_SEC_IN_JIFFIES){ - sec = MAX_SEC_IN_JIFFIES; - usec = 0; - } - return (((u64)sec * SEC_CONVERSION) + - (((u64)usec * USEC_CONVERSION + USEC_ROUND) >> - (USEC_JIFFIE_SC - SEC_JIFFIE_SC))) >> SEC_JIFFIE_SC; -} - -static __inline__ void -jiffies_to_timeval(const unsigned long jiffies, struct timeval *value) -{ - /* - * Convert jiffies to nanoseconds and separate with - * one divide. - */ - u64 nsec = (u64)jiffies * TICK_NSEC; - long tv_usec; - - value->tv_sec = div_long_long_rem(nsec, NSEC_PER_SEC, &tv_usec); - tv_usec /= NSEC_PER_USEC; - value->tv_usec = tv_usec; -} - -/* - * Convert jiffies/jiffies_64 to clock_t and back. + * Convert various time units to each other: */ -static inline clock_t jiffies_to_clock_t(long x) -{ -#if (TICK_NSEC % (NSEC_PER_SEC / USER_HZ)) == 0 - return x / (HZ / USER_HZ); -#else - u64 tmp = (u64)x * TICK_NSEC; - do_div(tmp, (NSEC_PER_SEC / USER_HZ)); - return (long)tmp; -#endif -} - -static inline unsigned long clock_t_to_jiffies(unsigned long x) -{ -#if (HZ % USER_HZ)==0 - if (x >= ~0UL / (HZ / USER_HZ)) - return ~0UL; - return x * (HZ / USER_HZ); -#else - u64 jif; - - /* Don't worry about loss of precision here .. */ - if (x >= ~0UL / HZ * USER_HZ) - return ~0UL; - - /* .. but do try to contain it here */ - jif = x * (u64) HZ; - do_div(jif, USER_HZ); - return jif; -#endif -} - -static inline u64 jiffies_64_to_clock_t(u64 x) -{ -#if (TICK_NSEC % (NSEC_PER_SEC / USER_HZ)) == 0 - do_div(x, HZ / USER_HZ); -#else - /* - * There are better ways that don't overflow early, - * but even this doesn't overflow in hundreds of years - * in 64 bits, so.. - */ - x *= TICK_NSEC; - do_div(x, (NSEC_PER_SEC / USER_HZ)); -#endif - return x; -} - -static inline u64 nsec_to_clock_t(u64 x) -{ -#if (NSEC_PER_SEC % USER_HZ) == 0 - do_div(x, (NSEC_PER_SEC / USER_HZ)); -#elif (USER_HZ % 512) == 0 - x *= USER_HZ/512; - do_div(x, (NSEC_PER_SEC / 512)); -#else - /* - * max relative error 5.7e-8 (1.8s per year) for USER_HZ <= 1024, - * overflow after 64.99 years. - * exact for HZ=60, 72, 90, 120, 144, 180, 300, 600, 900, ... - */ - x *= 9; - do_div(x, (unsigned long)((9ull * NSEC_PER_SEC + (USER_HZ/2)) - / USER_HZ)); -#endif - return x; -} +extern unsigned int jiffies_to_msecs(const unsigned long j); +extern unsigned int jiffies_to_usecs(const unsigned long j); +extern unsigned long msecs_to_jiffies(const unsigned int m); +extern unsigned long usecs_to_jiffies(const unsigned int u); +extern unsigned long timespec_to_jiffies(const struct timespec *value); +extern void jiffies_to_timespec(const unsigned long jiffies, + struct timespec *value); +extern unsigned long timeval_to_jiffies(const struct timeval *value); +extern void jiffies_to_timeval(const unsigned long jiffies, + struct timeval *value); +extern clock_t jiffies_to_clock_t(long x); +extern unsigned long clock_t_to_jiffies(unsigned long x); +extern u64 jiffies_64_to_clock_t(u64 x); +extern u64 nsec_to_clock_t(u64 x); + +#define TIMESTAMP_SIZE 30 #endif |