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c33c978915
freebsd/sys/sys/timeffc.h
Lawrence Stewart 6cedd609b7 Introduce the sysclock_getsnapshot() and sysclock_snap2bintime() KPIs. The 
sysclock_getsnapshot() function allows the caller to obtain a snapshot of all
the system clock and timecounter state required to create time stamps at a later
point. The sysclock_snap2bintime() function converts a previously obtained
snapshot into a bintime time stamp according to the specified flags e.g. which
system clock, uptime vs absolute time, etc.

These KPIs enable useful functionality, including direct comparison of the
feedback and feed-forward system clocks and generation of multiple time stamps
with different formats from a single timecounter read.

Committed on behalf of Julien Ridoux and Darryl Veitch from the University of
Melbourne, Australia, as part of the FreeBSD Foundation funded "Feed-Forward
Clock Synchronization Algorithms" project.

For more information, see http://www.synclab.org/radclock/

In collaboration with:	Julien Ridoux (jridoux at unimelb edu au)
2011-12-24 01:32:01 +00:00

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/*-
* Copyright (c) 2011 The University of Melbourne
* All rights reserved.
*
* This software was developed by Julien Ridoux at the University of Melbourne
* under sponsorship from the FreeBSD Foundation.
*
* Redistribution and use in source and binary forms, with or without
* modification, are permitted provided that the following conditions
* are met:
* 1. Redistributions of source code must retain the above copyright
* notice, this list of conditions and the following disclaimer.
* 2. Redistributions in binary form must reproduce the above copyright
* notice, this list of conditions and the following disclaimer in the
* documentation and/or other materials provided with the distribution.
*
* THIS SOFTWARE IS PROVIDED BY THE AUTHOR AND CONTRIBUTORS ``AS IS'' AND
* ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
* IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
* ARE DISCLAIMED. IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS BE LIABLE
* FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
* DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
* OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
* HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
* LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
* OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
* SUCH DAMAGE.
*
* $FreeBSD$
*/
#ifndef _SYS_TIMEFF_H_
#define _SYS_TIMEFF_H_
#include <sys/_ffcounter.h>
/*
* Feed-forward clock estimate
* Holds time mark as a ffcounter and conversion to bintime based on current
* timecounter period and offset estimate passed by the synchronization daemon.
* Provides time of last daemon update, clock status and bound on error.
*/
struct ffclock_estimate {
struct bintime update_time; /* Time of last estimates update. */
ffcounter update_ffcount; /* Counter value at last update. */
ffcounter leapsec_next; /* Counter value of next leap second. */
uint64_t period; /* Estimate of counter period. */
uint32_t errb_abs; /* Bound on absolute clock error [ns]. */
uint32_t errb_rate; /* Bound on counter rate error [ps/s]. */
uint32_t status; /* Clock status. */
int16_t leapsec_total; /* All leap seconds seen so far. */
int8_t leapsec; /* Next leap second (in {-1,0,1}). */
};
#if __BSD_VISIBLE
#ifdef _KERNEL
/* Define the kern.sysclock sysctl tree. */
SYSCTL_DECL(_kern_sysclock);
/* Define the kern.sysclock.ffclock sysctl tree. */
SYSCTL_DECL(_kern_sysclock_ffclock);
/*
* Index into the sysclocks array for obtaining the ASCII name of a particular
* sysclock.
*/
#define SYSCLOCK_FBCK 0
#define SYSCLOCK_FFWD 1
extern int sysclock_active;
/*
* Parameters of counter characterisation required by feed-forward algorithms.
*/
#define FFCLOCK_SKM_SCALE 1024
/*
* Feed-forward clock status
*/
#define FFCLOCK_STA_UNSYNC 1
#define FFCLOCK_STA_WARMUP 2
/*
* Flags for use by sysclock_snap2bintime() and various ffclock_ functions to
* control how the timecounter hardware is read and how the hardware snapshot is
* converted into absolute time.
* {FB|FF}CLOCK_FAST: Do not read the hardware counter, instead using the
* value at last tick. The time returned has a resolution
* of the kernel tick timer (1/hz [s]).
* FFCLOCK_LERP: Linear interpolation of ffclock time to guarantee
* monotonic time.
* FFCLOCK_LEAPSEC: Include leap seconds.
* {FB|FF}CLOCK_UPTIME: Time stamp should be relative to system boot, not epoch.
*/
#define FFCLOCK_FAST 0x00000001
#define FFCLOCK_LERP 0x00000002
#define FFCLOCK_LEAPSEC 0x00000004
#define FFCLOCK_UPTIME 0x00000008
#define FFCLOCK_MASK 0x0000ffff
#define FBCLOCK_FAST 0x00010000 /* Currently unused. */
#define FBCLOCK_UPTIME 0x00020000
#define FBCLOCK_MASK 0xffff0000
/*
* Feedback clock specific info structure. The feedback clock's estimation of
* clock error is an absolute figure determined by the NTP algorithm. The status
* is determined by the userland daemon.
*/
struct fbclock_info {
struct bintime error;
struct bintime tick_time;
uint64_t th_scale;
int status;
};
/*
* Feed-forward clock specific info structure. The feed-forward clock's
* estimation of clock error is an upper bound, which although potentially
* looser than the feedback clock equivalent, is much more reliable. The status
* is determined by the userland daemon.
*/
struct ffclock_info {
struct bintime error;
struct bintime tick_time;
struct bintime tick_time_lerp;
uint64_t period;
uint64_t period_lerp;
int leapsec_adjustment;
int status;
};
/*
* Snapshot of system clocks and related information. Holds time read from each
* clock based on a single read of the active hardware timecounter, as well as
* respective clock information such as error estimates and the ffcounter value
* at the time of the read.
*/
struct sysclock_snap {
struct fbclock_info fb_info;
struct ffclock_info ff_info;
ffcounter ffcount;
unsigned int delta;
int sysclock_active;
};
/* Take a snapshot of the system clocks and related information. */
void sysclock_getsnapshot(struct sysclock_snap *clock_snap, int fast);
/* Convert a timestamp from the selected system clock into bintime. */
int sysclock_snap2bintime(struct sysclock_snap *cs, struct bintime *bt,
int whichclock, uint32_t flags);
/* Resets feed-forward clock from RTC */
void ffclock_reset_clock(struct timespec *ts);
/*
* Return the current value of the feed-forward clock counter. Essential to
* measure time interval in counter units. If a fast timecounter is used by the
* system, may also allow fast but accurate timestamping.
*/
void ffclock_read_counter(ffcounter *ffcount);
/*
* Retrieve feed-forward counter value and time of last kernel tick. This
* accepts the FFCLOCK_LERP flag.
*/
void ffclock_last_tick(ffcounter *ffcount, struct bintime *bt, uint32_t flags);
/*
* Low level routines to convert a counter timestamp into absolute time and a
* counter timestamp interval into an interval in seconds. The absolute time
* conversion accepts the FFCLOCK_LERP flag.
*/
void ffclock_convert_abs(ffcounter ffcount, struct bintime *bt, uint32_t flags);
void ffclock_convert_diff(ffcounter ffdelta, struct bintime *bt);
/*
* Feed-forward clock routines.
*
* These functions rely on the timecounters and ffclock_estimates stored in
* fftimehands. Note that the error_bound parameter is not the error of the
* clock but an upper bound on the error of the absolute time or time interval
* returned.
*
* ffclock_abstime(): retrieves current time as counter value and convert this
* timestamp in seconds. The value (in seconds) of the converted timestamp
* depends on the flags passed: for a given counter value, different
* conversions are possible. Different clock models can be selected by
* combining flags (for example (FFCLOCK_LERP|FFCLOCK_UPTIME) produces
* linearly interpolated uptime).
* ffclock_difftime(): computes a time interval in seconds based on an interval
* measured in ffcounter units. This should be the preferred way to measure
* small time intervals very accurately.
*/
void ffclock_abstime(ffcounter *ffcount, struct bintime *bt,
struct bintime *error_bound, uint32_t flags);
void ffclock_difftime(ffcounter ffdelta, struct bintime *bt,
struct bintime *error_bound);
/*
* Wrapper routines to return current absolute time using the feed-forward
* clock. These functions are named after those defined in <sys/time.h>, which
* contains a description of the original ones.
*/
void ffclock_bintime(struct bintime *bt);
void ffclock_nanotime(struct timespec *tsp);
void ffclock_microtime(struct timeval *tvp);
void ffclock_getbintime(struct bintime *bt);
void ffclock_getnanotime(struct timespec *tsp);
void ffclock_getmicrotime(struct timeval *tvp);
void ffclock_binuptime(struct bintime *bt);
void ffclock_nanouptime(struct timespec *tsp);
void ffclock_microuptime(struct timeval *tvp);
void ffclock_getbinuptime(struct bintime *bt);
void ffclock_getnanouptime(struct timespec *tsp);
void ffclock_getmicrouptime(struct timeval *tvp);
/*
* Wrapper routines to convert a time interval specified in ffcounter units into
* seconds using the current feed-forward clock estimates.
*/
void ffclock_bindifftime(ffcounter ffdelta, struct bintime *bt);
void ffclock_nanodifftime(ffcounter ffdelta, struct timespec *tsp);
void ffclock_microdifftime(ffcounter ffdelta, struct timeval *tvp);
/*
* When FFCLOCK is enabled in the kernel, [get]{bin,nano,micro}[up]time() become
* wrappers around equivalent feedback or feed-forward functions. Provide access
* outside of kern_tc.c to the feedback clock equivalent functions for
* specialised use i.e. these are not for general consumption.
*/
void fbclock_bintime(struct bintime *bt);
void fbclock_nanotime(struct timespec *tsp);
void fbclock_microtime(struct timeval *tvp);
void fbclock_getbintime(struct bintime *bt);
void fbclock_getnanotime(struct timespec *tsp);
void fbclock_getmicrotime(struct timeval *tvp);
void fbclock_binuptime(struct bintime *bt);
void fbclock_nanouptime(struct timespec *tsp);
void fbclock_microuptime(struct timeval *tvp);
void fbclock_getbinuptime(struct bintime *bt);
void fbclock_getnanouptime(struct timespec *tsp);
void fbclock_getmicrouptime(struct timeval *tvp);
/*
* Public system clock wrapper API which allows consumers to select which clock
* to obtain time from, independent of the current default system clock. These
* wrappers should be used instead of directly calling the underlying fbclock_
* or ffclock_ functions.
*/
static inline void
bintime_fromclock(struct bintime *bt, int whichclock)
{
if (whichclock == SYSCLOCK_FFWD)
ffclock_bintime(bt);
else
fbclock_bintime(bt);
}
static inline void
nanotime_fromclock(struct timespec *tsp, int whichclock)
{
if (whichclock == SYSCLOCK_FFWD)
ffclock_nanotime(tsp);
else
fbclock_nanotime(tsp);
}
static inline void
microtime_fromclock(struct timeval *tvp, int whichclock)
{
if (whichclock == SYSCLOCK_FFWD)
ffclock_microtime(tvp);
else
fbclock_microtime(tvp);
}
static inline void
getbintime_fromclock(struct bintime *bt, int whichclock)
{
if (whichclock == SYSCLOCK_FFWD)
ffclock_getbintime(bt);
else
fbclock_getbintime(bt);
}
static inline void
getnanotime_fromclock(struct timespec *tsp, int whichclock)
{
if (whichclock == SYSCLOCK_FFWD)
ffclock_getnanotime(tsp);
else
fbclock_getnanotime(tsp);
}
static inline void
getmicrotime_fromclock(struct timeval *tvp, int whichclock)
{
if (whichclock == SYSCLOCK_FFWD)
ffclock_getmicrotime(tvp);
else
fbclock_getmicrotime(tvp);
}
static inline void
binuptime_fromclock(struct bintime *bt, int whichclock)
{
if (whichclock == SYSCLOCK_FFWD)
ffclock_binuptime(bt);
else
fbclock_binuptime(bt);
}
static inline void
nanouptime_fromclock(struct timespec *tsp, int whichclock)
{
if (whichclock == SYSCLOCK_FFWD)
ffclock_nanouptime(tsp);
else
fbclock_nanouptime(tsp);
}
static inline void
microuptime_fromclock(struct timeval *tvp, int whichclock)
{
if (whichclock == SYSCLOCK_FFWD)
ffclock_microuptime(tvp);
else
fbclock_microuptime(tvp);
}
static inline void
getbinuptime_fromclock(struct bintime *bt, int whichclock)
{
if (whichclock == SYSCLOCK_FFWD)
ffclock_getbinuptime(bt);
else
fbclock_getbinuptime(bt);
}
static inline void
getnanouptime_fromclock(struct timespec *tsp, int whichclock)
{
if (whichclock == SYSCLOCK_FFWD)
ffclock_getnanouptime(tsp);
else
fbclock_getnanouptime(tsp);
}
static inline void
getmicrouptime_fromclock(struct timeval *tvp, int whichclock)
{
if (whichclock == SYSCLOCK_FFWD)
ffclock_getmicrouptime(tvp);
else
fbclock_getmicrouptime(tvp);
}
#else /* !_KERNEL */
/* Feed-Forward Clock system calls. */
__BEGIN_DECLS
int ffclock_getcounter(ffcounter *ffcount);
int ffclock_getestimate(struct ffclock_estimate *cest);
int ffclock_setestimate(struct ffclock_estimate *cest);
__END_DECLS
#endif /* _KERNEL */
#endif /* __BSD_VISIBLE */
#endif /* _SYS_TIMEFF_H_ */
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