From 97fc79f97b1111c80010d34ee66312b88f531e41 Mon Sep 17 00:00:00 2001 From: Thomas Gleixner Date: Mon, 9 Jan 2006 20:52:31 -0800 Subject: [PATCH] hrtimer: introduce ktime_t time format - introduce ktime_t: nanosecond-resolution time format. - eliminate the plain s64 scalar type, and always use the union. This simplifies the arithmetics. Idea from Roman Zippel. Signed-off-by: Thomas Gleixner Signed-off-by: Ingo Molnar Signed-off-by: Andrew Morton Signed-off-by: Linus Torvalds --- arch/i386/Kconfig | 4 + include/linux/ktime.h | 269 ++++++++++++++++++++++++++++++++++++++++++++++++++ 2 files changed, 273 insertions(+) create mode 100644 include/linux/ktime.h diff --git a/arch/i386/Kconfig b/arch/i386/Kconfig index 554ce3f344c9a..815878ebd30f0 100644 --- a/arch/i386/Kconfig +++ b/arch/i386/Kconfig @@ -1060,3 +1060,7 @@ config X86_TRAMPOLINE bool depends on X86_SMP || (X86_VOYAGER && SMP) default y + +config KTIME_SCALAR + bool + default y diff --git a/include/linux/ktime.h b/include/linux/ktime.h new file mode 100644 index 0000000000000..5b9a9eb82baab --- /dev/null +++ b/include/linux/ktime.h @@ -0,0 +1,269 @@ +/* + * include/linux/ktime.h + * + * ktime_t - nanosecond-resolution time format. + * + * Copyright(C) 2005, Thomas Gleixner + * Copyright(C) 2005, Red Hat, Inc., Ingo Molnar + * + * data type definitions, declarations, prototypes and macros. + * + * Started by: Thomas Gleixner and Ingo Molnar + * + * For licencing details see kernel-base/COPYING + */ +#ifndef _LINUX_KTIME_H +#define _LINUX_KTIME_H + +#include +#include + +/* + * ktime_t: + * + * On 64-bit CPUs a single 64-bit variable is used to store the hrtimers + * internal representation of time values in scalar nanoseconds. The + * design plays out best on 64-bit CPUs, where most conversions are + * NOPs and most arithmetic ktime_t operations are plain arithmetic + * operations. + * + * On 32-bit CPUs an optimized representation of the timespec structure + * is used to avoid expensive conversions from and to timespecs. The + * endian-aware order of the tv struct members is choosen to allow + * mathematical operations on the tv64 member of the union too, which + * for certain operations produces better code. + * + * For architectures with efficient support for 64/32-bit conversions the + * plain scalar nanosecond based representation can be selected by the + * config switch CONFIG_KTIME_SCALAR. + */ +typedef union { + s64 tv64; +#if BITS_PER_LONG != 64 && !defined(CONFIG_KTIME_SCALAR) + struct { +# ifdef __BIG_ENDIAN + s32 sec, nsec; +# else + s32 nsec, sec; +# endif + } tv; +#endif +} ktime_t; + +#define KTIME_MAX (~((u64)1 << 63)) + +/* + * ktime_t definitions when using the 64-bit scalar representation: + */ + +#if (BITS_PER_LONG == 64) || defined(CONFIG_KTIME_SCALAR) + +/* Define a ktime_t variable and initialize it to zero: */ +#define DEFINE_KTIME(kt) ktime_t kt = { .tv64 = 0 } + +/** + * ktime_set - Set a ktime_t variable from a seconds/nanoseconds value + * + * @secs: seconds to set + * @nsecs: nanoseconds to set + * + * Return the ktime_t representation of the value + */ +static inline ktime_t ktime_set(const long secs, const unsigned long nsecs) +{ + return (ktime_t) { .tv64 = (s64)secs * NSEC_PER_SEC + (s64)nsecs }; +} + +/* Subtract two ktime_t variables. rem = lhs -rhs: */ +#define ktime_sub(lhs, rhs) \ + ({ (ktime_t){ .tv64 = (lhs).tv64 - (rhs).tv64 }; }) + +/* Add two ktime_t variables. res = lhs + rhs: */ +#define ktime_add(lhs, rhs) \ + ({ (ktime_t){ .tv64 = (lhs).tv64 + (rhs).tv64 }; }) + +/* + * Add a ktime_t variable and a scalar nanosecond value. + * res = kt + nsval: + */ +#define ktime_add_ns(kt, nsval) \ + ({ (ktime_t){ .tv64 = (kt).tv64 + (nsval) }; }) + +/* convert a timespec to ktime_t format: */ +#define timespec_to_ktime(ts) ktime_set((ts).tv_sec, (ts).tv_nsec) + +/* convert a timeval to ktime_t format: */ +#define timeval_to_ktime(tv) ktime_set((tv).tv_sec, (tv).tv_usec * 1000) + +/* Map the ktime_t to timespec conversion to ns_to_timespec function */ +#define ktime_to_timespec(kt) ns_to_timespec((kt).tv64) + +/* Map the ktime_t to timeval conversion to ns_to_timeval function */ +#define ktime_to_timeval(kt) ns_to_timeval((kt).tv64) + +/* Map the ktime_t to clock_t conversion to the inline in jiffies.h: */ +#define ktime_to_clock_t(kt) nsec_to_clock_t((kt).tv64) + +/* Convert ktime_t to nanoseconds - NOP in the scalar storage format: */ +#define ktime_to_ns(kt) ((kt).tv64) + +#else + +/* + * Helper macros/inlines to get the ktime_t math right in the timespec + * representation. The macros are sometimes ugly - their actual use is + * pretty okay-ish, given the circumstances. We do all this for + * performance reasons. The pure scalar nsec_t based code was nice and + * simple, but created too many 64-bit / 32-bit conversions and divisions. + * + * Be especially aware that negative values are represented in a way + * that the tv.sec field is negative and the tv.nsec field is greater + * or equal to zero but less than nanoseconds per second. This is the + * same representation which is used by timespecs. + * + * tv.sec < 0 and 0 >= tv.nsec < NSEC_PER_SEC + */ + +/* Define a ktime_t variable and initialize it to zero: */ +#define DEFINE_KTIME(kt) ktime_t kt = { .tv64 = 0 } + +/* Set a ktime_t variable to a value in sec/nsec representation: */ +static inline ktime_t ktime_set(const long secs, const unsigned long nsecs) +{ + return (ktime_t) { .tv = { .sec = secs, .nsec = nsecs } }; +} + +/** + * ktime_sub - subtract two ktime_t variables + * + * @lhs: minuend + * @rhs: subtrahend + * + * Returns the remainder of the substraction + */ +static inline ktime_t ktime_sub(const ktime_t lhs, const ktime_t rhs) +{ + ktime_t res; + + res.tv64 = lhs.tv64 - rhs.tv64; + if (res.tv.nsec < 0) + res.tv.nsec += NSEC_PER_SEC; + + return res; +} + +/** + * ktime_add - add two ktime_t variables + * + * @add1: addend1 + * @add2: addend2 + * + * Returns the sum of addend1 and addend2 + */ +static inline ktime_t ktime_add(const ktime_t add1, const ktime_t add2) +{ + ktime_t res; + + res.tv64 = add1.tv64 + add2.tv64; + /* + * performance trick: the (u32) -NSEC gives 0x00000000Fxxxxxxx + * so we subtract NSEC_PER_SEC and add 1 to the upper 32 bit. + * + * it's equivalent to: + * tv.nsec -= NSEC_PER_SEC + * tv.sec ++; + */ + if (res.tv.nsec >= NSEC_PER_SEC) + res.tv64 += (u32)-NSEC_PER_SEC; + + return res; +} + +/** + * ktime_add_ns - Add a scalar nanoseconds value to a ktime_t variable + * + * @kt: addend + * @nsec: the scalar nsec value to add + * + * Returns the sum of kt and nsec in ktime_t format + */ +extern ktime_t ktime_add_ns(const ktime_t kt, u64 nsec); + +/** + * timespec_to_ktime - convert a timespec to ktime_t format + * + * @ts: the timespec variable to convert + * + * Returns a ktime_t variable with the converted timespec value + */ +static inline ktime_t timespec_to_ktime(const struct timespec ts) +{ + return (ktime_t) { .tv = { .sec = (s32)ts.tv_sec, + .nsec = (s32)ts.tv_nsec } }; +} + +/** + * timeval_to_ktime - convert a timeval to ktime_t format + * + * @tv: the timeval variable to convert + * + * Returns a ktime_t variable with the converted timeval value + */ +static inline ktime_t timeval_to_ktime(const struct timeval tv) +{ + return (ktime_t) { .tv = { .sec = (s32)tv.tv_sec, + .nsec = (s32)tv.tv_usec * 1000 } }; +} + +/** + * ktime_to_timespec - convert a ktime_t variable to timespec format + * + * @kt: the ktime_t variable to convert + * + * Returns the timespec representation of the ktime value + */ +static inline struct timespec ktime_to_timespec(const ktime_t kt) +{ + return (struct timespec) { .tv_sec = (time_t) kt.tv.sec, + .tv_nsec = (long) kt.tv.nsec }; +} + +/** + * ktime_to_timeval - convert a ktime_t variable to timeval format + * + * @kt: the ktime_t variable to convert + * + * Returns the timeval representation of the ktime value + */ +static inline struct timeval ktime_to_timeval(const ktime_t kt) +{ + return (struct timeval) { + .tv_sec = (time_t) kt.tv.sec, + .tv_usec = (suseconds_t) (kt.tv.nsec / NSEC_PER_USEC) }; +} + +/** + * ktime_to_clock_t - convert a ktime_t variable to clock_t format + * @kt: the ktime_t variable to convert + * + * Returns a clock_t variable with the converted value + */ +static inline clock_t ktime_to_clock_t(const ktime_t kt) +{ + return nsec_to_clock_t( (u64) kt.tv.sec * NSEC_PER_SEC + kt.tv.nsec); +} + +/** + * ktime_to_ns - convert a ktime_t variable to scalar nanoseconds + * @kt: the ktime_t variable to convert + * + * Returns the scalar nanoseconds representation of kt + */ +static inline u64 ktime_to_ns(const ktime_t kt) +{ + return (u64) kt.tv.sec * NSEC_PER_SEC + kt.tv.nsec; +} + +#endif + +#endif -- cgit 1.2.3-korg