Commit 97fc79f9 authored by Thomas Gleixner's avatar Thomas Gleixner Committed by Linus Torvalds
Browse files

[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: default avatarThomas Gleixner <tglx@linutronix.de>
Signed-off-by: default avatarIngo Molnar <mingo@elte.hu>
Signed-off-by: default avatarAndrew Morton <akpm@osdl.org>
Signed-off-by: default avatarLinus Torvalds <torvalds@osdl.org>
parent f8f46da3
......@@ -1060,3 +1060,7 @@ config X86_TRAMPOLINE
bool
depends on X86_SMP || (X86_VOYAGER && SMP)
default y
config KTIME_SCALAR
bool
default y
/*
* include/linux/ktime.h
*
* ktime_t - nanosecond-resolution time format.
*
* Copyright(C) 2005, Thomas Gleixner <tglx@linutronix.de>
* 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 <linux/time.h>
#include <linux/jiffies.h>
/*
* 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
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