d/freebsd-skq
1
0
Fork 0
Code Issues Pull Requests Packages Projects Releases Wiki Activity
ee509b6933
freebsd-skq/sys/kern/kern_ntptime.c

270 lines
8.0 KiB
C
Raw Normal View History

Redo Kernel NTP PLL support, kernel side. This code is mostly taken from the 1.1 port (which was in turn taken from Dave Mills's kern.tar.Z example). A few significant differences: 1) ntp_gettime() is now a MIB variable rather than a system call. A few fiddles are done in libc to make it behave the same. 2) mono_time does not participate in the PLL adjustments. 3) A new interface has been defined (in <machine/clock.h>) for doing possibly machine-dependent things around the time of the clock update. This is used in Pentium kernels to disable interrupts, set `time', and reset the CPU cycle counter as quickly as possible to avoid jitter in microtime(). Measurements show an apparent resolution of a bit more than 8.14usec, which is reasonable given system-call overhead.
1994-09-18 20:40:01 +00:00
/******************************************************************************
* *
* Copyright (c) David L. Mills 1993, 1994 *
* *
* Permission to use, copy, modify, and distribute this software and its *
* documentation for any purpose and without fee is hereby granted, provided *
* that the above copyright notice appears in all copies and that both the *
* copyright notice and this permission notice appear in supporting *
* documentation, and that the name University of Delaware not be used in *
* advertising or publicity pertaining to distribution of the software *
* without specific, written prior permission. The University of Delaware *
* makes no representations about the suitability this software for any *
* purpose. It is provided "as is" without express or implied warranty. *
* *
******************************************************************************/
/*
* Modification history kern_ntptime.c
*
Update our kernel ntp code to the latest from David Mills. The main change is the addition of the FLL code, which is used by the latest versions of xntpd. The kernel PPS code is also updated, although I can't test that yet.
1996-12-30 18:26:28 +00:00
* 24 Sep 94 David L. Mills
* Tightened code at exits.
*
Redo Kernel NTP PLL support, kernel side. This code is mostly taken from the 1.1 port (which was in turn taken from Dave Mills's kern.tar.Z example). A few significant differences: 1) ntp_gettime() is now a MIB variable rather than a system call. A few fiddles are done in libc to make it behave the same. 2) mono_time does not participate in the PLL adjustments. 3) A new interface has been defined (in <machine/clock.h>) for doing possibly machine-dependent things around the time of the clock update. This is used in Pentium kernels to disable interrupts, set `time', and reset the CPU cycle counter as quickly as possible to avoid jitter in microtime(). Measurements show an apparent resolution of a bit more than 8.14usec, which is reasonable given system-call overhead.
1994-09-18 20:40:01 +00:00
* 24 Mar 94 David L. Mills
* Revised syscall interface to include new variables for PPS
* time discipline.
*
* 14 Feb 94 David L. Mills
* Added code for external clock
*
* 28 Nov 93 David L. Mills
* Revised frequency scaling to conform with adjusted parameters
*
* 17 Sep 93 David L. Mills
* Created file
*/
/*
* ntp_gettime(), ntp_adjtime() - precision time interface for SunOS
Update our kernel ntp code to the latest from David Mills. The main change is the addition of the FLL code, which is used by the latest versions of xntpd. The kernel PPS code is also updated, although I can't test that yet.
1996-12-30 18:26:28 +00:00
* V4.1.1 and V4.1.3
Redo Kernel NTP PLL support, kernel side. This code is mostly taken from the 1.1 port (which was in turn taken from Dave Mills's kern.tar.Z example). A few significant differences: 1) ntp_gettime() is now a MIB variable rather than a system call. A few fiddles are done in libc to make it behave the same. 2) mono_time does not participate in the PLL adjustments. 3) A new interface has been defined (in <machine/clock.h>) for doing possibly machine-dependent things around the time of the clock update. This is used in Pentium kernels to disable interrupts, set `time', and reset the CPU cycle counter as quickly as possible to avoid jitter in microtime(). Measurements show an apparent resolution of a bit more than 8.14usec, which is reasonable given system-call overhead.
1994-09-18 20:40:01 +00:00
*
* These routines consitute the Network Time Protocol (NTP) interfaces
* for user and daemon application programs. The ntp_gettime() routine
* provides the time, maximum error (synch distance) and estimated error
* (dispersion) to client user application programs. The ntp_adjtime()
* routine is used by the NTP daemon to adjust the system clock to an
* externally derived time. The time offset and related variables set by
* this routine are used by hardclock() to adjust the phase and
* frequency of the phase-lock loop which controls the system clock.
*/
#include <sys/param.h>
#include <sys/systm.h>
Included <sys/sysproto.h> to get central declarations for syscall args structs and prototypes for syscalls. Ifdefed duplicated decentralized declarations of args structs. It's convenient to have this visible but they are hard to maintain. Some are already different from the central declarations. 4.4lite2 puts them in comments in the function headers but I wanted to avoid the large changes for that.
1995-11-12 06:43:28 +00:00
#include <sys/sysproto.h>
Redo Kernel NTP PLL support, kernel side. This code is mostly taken from the 1.1 port (which was in turn taken from Dave Mills's kern.tar.Z example). A few significant differences: 1) ntp_gettime() is now a MIB variable rather than a system call. A few fiddles are done in libc to make it behave the same. 2) mono_time does not participate in the PLL adjustments. 3) A new interface has been defined (in <machine/clock.h>) for doing possibly machine-dependent things around the time of the clock update. This is used in Pentium kernels to disable interrupts, set `time', and reset the CPU cycle counter as quickly as possible to avoid jitter in microtime(). Measurements show an apparent resolution of a bit more than 8.14usec, which is reasonable given system-call overhead.
1994-09-18 20:40:01 +00:00
#include <sys/kernel.h>
#include <sys/proc.h>
#include <sys/timex.h>
#include <sys/sysctl.h>
/*
* The following variables are used by the hardclock() routine in the
Remove trailing whitespace.
1995-05-30 08:16:23 +00:00
* kern_clock.c module and are described in that module.
Redo Kernel NTP PLL support, kernel side. This code is mostly taken from the 1.1 port (which was in turn taken from Dave Mills's kern.tar.Z example). A few significant differences: 1) ntp_gettime() is now a MIB variable rather than a system call. A few fiddles are done in libc to make it behave the same. 2) mono_time does not participate in the PLL adjustments. 3) A new interface has been defined (in <machine/clock.h>) for doing possibly machine-dependent things around the time of the clock update. This is used in Pentium kernels to disable interrupts, set `time', and reset the CPU cycle counter as quickly as possible to avoid jitter in microtime(). Measurements show an apparent resolution of a bit more than 8.14usec, which is reasonable given system-call overhead.
1994-09-18 20:40:01 +00:00
*/
extern int time_state; /* clock state */
extern int time_status; /* clock status bits */
extern long time_offset; /* time adjustment (us) */
extern long time_freq; /* frequency offset (scaled ppm) */
extern long time_maxerror; /* maximum error (us) */
extern long time_esterror; /* estimated error (us) */
extern long time_constant; /* pll time constant */
extern long time_precision; /* clock precision (us) */
extern long time_tolerance; /* frequency tolerance (scaled ppm) */
#ifdef PPS_SYNC
/*
* The following variables are used only if the PPS signal discipline
* is configured in the kernel.
*/
extern int pps_shift; /* interval duration (s) (shift) */
extern long pps_freq; /* pps frequency offset (scaled ppm) */
extern long pps_jitter; /* pps jitter (us) */
extern long pps_stabil; /* pps stability (scaled ppm) */
extern long pps_jitcnt; /* jitter limit exceeded */
extern long pps_calcnt; /* calibration intervals */
extern long pps_errcnt; /* calibration errors */
extern long pps_stbcnt; /* stability limit exceeded */
#endif /* PPS_SYNC */
Move KERN_NTP to a more suitable file.
1995-11-14 09:07:14 +00:00
static int
ntp_sysctl SYSCTL_HANDLER_ARGS
Redo Kernel NTP PLL support, kernel side. This code is mostly taken from the 1.1 port (which was in turn taken from Dave Mills's kern.tar.Z example). A few significant differences: 1) ntp_gettime() is now a MIB variable rather than a system call. A few fiddles are done in libc to make it behave the same. 2) mono_time does not participate in the PLL adjustments. 3) A new interface has been defined (in <machine/clock.h>) for doing possibly machine-dependent things around the time of the clock update. This is used in Pentium kernels to disable interrupts, set `time', and reset the CPU cycle counter as quickly as possible to avoid jitter in microtime(). Measurements show an apparent resolution of a bit more than 8.14usec, which is reasonable given system-call overhead.
1994-09-18 20:40:01 +00:00
{
struct timeval atv;
struct ntptimeval ntv;
int s;
s = splclock();
#ifdef EXT_CLOCK
/*
* The microtime() external clock routine returns a
* status code. If less than zero, we declare an error
* in the clock status word and return the kernel
* (software) time variable. While there are other
* places that call microtime(), this is the only place
* that matters from an application point of view.
*/
if (microtime(&atv) < 0) {
time_status |= STA_CLOCKERR;
ntv.time = time;
} else {
time_status &= ~STA_CLOCKERR;
}
#else /* EXT_CLOCK */
microtime(&atv);
#endif /* EXT_CLOCK */
ntv.time = atv;
ntv.maxerror = time_maxerror;
ntv.esterror = time_esterror;
splx(s);
Remove trailing whitespace.
1995-05-30 08:16:23 +00:00
Redo Kernel NTP PLL support, kernel side. This code is mostly taken from the 1.1 port (which was in turn taken from Dave Mills's kern.tar.Z example). A few significant differences: 1) ntp_gettime() is now a MIB variable rather than a system call. A few fiddles are done in libc to make it behave the same. 2) mono_time does not participate in the PLL adjustments. 3) A new interface has been defined (in <machine/clock.h>) for doing possibly machine-dependent things around the time of the clock update. This is used in Pentium kernels to disable interrupts, set `time', and reset the CPU cycle counter as quickly as possible to avoid jitter in microtime(). Measurements show an apparent resolution of a bit more than 8.14usec, which is reasonable given system-call overhead.
1994-09-18 20:40:01 +00:00
ntv.time_state = time_state;
/*
* Status word error decode. If any of these conditions
* occur, an error is returned, instead of the status
* word. Most applications will care only about the fact
* the system clock may not be trusted, not about the
* details.
*
* Hardware or software error
*/
if (time_status & (STA_UNSYNC | STA_CLOCKERR)) {
ntv.time_state = TIME_ERROR;
}
/*
* PPS signal lost when either time or frequency
* synchronization requested
*/
if (time_status & (STA_PPSFREQ | STA_PPSTIME) &&
!(time_status & STA_PPSSIGNAL)) {
ntv.time_state = TIME_ERROR;
}
/*
* PPS jitter exceeded when time synchronization
* requested
*/
if (time_status & STA_PPSTIME &&
time_status & STA_PPSJITTER) {
ntv.time_state = TIME_ERROR;
}
/*
* PPS wander exceeded or calibration error when
* frequency synchronization requested
*/
if (time_status & STA_PPSFREQ &&
time_status & (STA_PPSWANDER | STA_PPSERROR)) {
ntv.time_state = TIME_ERROR;
}
Move KERN_NTP to a more suitable file.
1995-11-14 09:07:14 +00:00
return (sysctl_handle_opaque(oidp, &ntv, sizeof ntv, req));
Redo Kernel NTP PLL support, kernel side. This code is mostly taken from the 1.1 port (which was in turn taken from Dave Mills's kern.tar.Z example). A few significant differences: 1) ntp_gettime() is now a MIB variable rather than a system call. A few fiddles are done in libc to make it behave the same. 2) mono_time does not participate in the PLL adjustments. 3) A new interface has been defined (in <machine/clock.h>) for doing possibly machine-dependent things around the time of the clock update. This is used in Pentium kernels to disable interrupts, set `time', and reset the CPU cycle counter as quickly as possible to avoid jitter in microtime(). Measurements show an apparent resolution of a bit more than 8.14usec, which is reasonable given system-call overhead.
1994-09-18 20:40:01 +00:00
}
Move KERN_NTP to a more suitable file.
1995-11-14 09:07:14 +00:00
SYSCTL_NODE(_kern, KERN_NTP_PLL, ntp_pll, CTLFLAG_RW, 0,
"NTP kernel PLL related stuff");
SYSCTL_PROC(_kern_ntp_pll, NTP_PLL_GETTIME, gettime, CTLTYPE_OPAQUE|CTLFLAG_RD,
A major sweep over the sysctl stuff. Move a lot of variables home to their own code (In good time before xmas :-) Introduce the string descrition of format. Add a couple more functions to poke into these marvels, while I try to decide what the correct interface should look like. Next is adding vars on the fly, and sysctl looking at them too. Removed a tine bit of defunct and #ifdefed notused code in swapgeneric.
1995-12-04 16:48:58 +00:00
0, sizeof(struct ntptimeval) , ntp_sysctl, "S,ntptimeval", "");
Move KERN_NTP to a more suitable file.
1995-11-14 09:07:14 +00:00
Redo Kernel NTP PLL support, kernel side. This code is mostly taken from the 1.1 port (which was in turn taken from Dave Mills's kern.tar.Z example). A few significant differences: 1) ntp_gettime() is now a MIB variable rather than a system call. A few fiddles are done in libc to make it behave the same. 2) mono_time does not participate in the PLL adjustments. 3) A new interface has been defined (in <machine/clock.h>) for doing possibly machine-dependent things around the time of the clock update. This is used in Pentium kernels to disable interrupts, set `time', and reset the CPU cycle counter as quickly as possible to avoid jitter in microtime(). Measurements show an apparent resolution of a bit more than 8.14usec, which is reasonable given system-call overhead.
1994-09-18 20:40:01 +00:00
/*
* ntp_adjtime() - NTP daemon application interface
*/
Included <sys/sysproto.h> to get central declarations for syscall args structs and prototypes for syscalls. Ifdefed duplicated decentralized declarations of args structs. It's convenient to have this visible but they are hard to maintain. Some are already different from the central declarations. 4.4lite2 puts them in comments in the function headers but I wanted to avoid the large changes for that.
1995-11-12 06:43:28 +00:00
#ifndef _SYS_SYSPROTO_H_
Redo Kernel NTP PLL support, kernel side. This code is mostly taken from the 1.1 port (which was in turn taken from Dave Mills's kern.tar.Z example). A few significant differences: 1) ntp_gettime() is now a MIB variable rather than a system call. A few fiddles are done in libc to make it behave the same. 2) mono_time does not participate in the PLL adjustments. 3) A new interface has been defined (in <machine/clock.h>) for doing possibly machine-dependent things around the time of the clock update. This is used in Pentium kernels to disable interrupts, set `time', and reset the CPU cycle counter as quickly as possible to avoid jitter in microtime(). Measurements show an apparent resolution of a bit more than 8.14usec, which is reasonable given system-call overhead.
1994-09-18 20:40:01 +00:00
struct ntp_adjtime_args {
struct timex *tp;
};
Included <sys/sysproto.h> to get central declarations for syscall args structs and prototypes for syscalls. Ifdefed duplicated decentralized declarations of args structs. It's convenient to have this visible but they are hard to maintain. Some are already different from the central declarations. 4.4lite2 puts them in comments in the function headers but I wanted to avoid the large changes for that.
1995-11-12 06:43:28 +00:00
#endif
Redo Kernel NTP PLL support, kernel side. This code is mostly taken from the 1.1 port (which was in turn taken from Dave Mills's kern.tar.Z example). A few significant differences: 1) ntp_gettime() is now a MIB variable rather than a system call. A few fiddles are done in libc to make it behave the same. 2) mono_time does not participate in the PLL adjustments. 3) A new interface has been defined (in <machine/clock.h>) for doing possibly machine-dependent things around the time of the clock update. This is used in Pentium kernels to disable interrupts, set `time', and reset the CPU cycle counter as quickly as possible to avoid jitter in microtime(). Measurements show an apparent resolution of a bit more than 8.14usec, which is reasonable given system-call overhead.
1994-09-18 20:40:01 +00:00
int
Move the "retval" (3rd) parameter from all syscall functions and put it in struct proc instead. This fixes a boatload of compiler warning, and removes a lot of cruft from the sources. I have not removed the /*ARGSUSED*/, they will require some looking at. libkvm, ps and other userland struct proc frobbing programs will need recompiled.
1997-11-06 19:29:57 +00:00
ntp_adjtime(struct proc *p, struct ntp_adjtime_args *uap)
Redo Kernel NTP PLL support, kernel side. This code is mostly taken from the 1.1 port (which was in turn taken from Dave Mills's kern.tar.Z example). A few significant differences: 1) ntp_gettime() is now a MIB variable rather than a system call. A few fiddles are done in libc to make it behave the same. 2) mono_time does not participate in the PLL adjustments. 3) A new interface has been defined (in <machine/clock.h>) for doing possibly machine-dependent things around the time of the clock update. This is used in Pentium kernels to disable interrupts, set `time', and reset the CPU cycle counter as quickly as possible to avoid jitter in microtime(). Measurements show an apparent resolution of a bit more than 8.14usec, which is reasonable given system-call overhead.
1994-09-18 20:40:01 +00:00
{
struct timex ntv;
int modes;
int s;
int error;
error = copyin((caddr_t)uap->tp, (caddr_t)&ntv, sizeof(ntv));
if (error)
return error;
/*
* Update selected clock variables - only the superuser can
* change anything. Note that there is no error checking here on
* the assumption the superuser should know what it is doing.
*/
modes = ntv.modes;
if ((modes != 0)
&& (error = suser(p->p_cred->pc_ucred, &p->p_acflag)))
return error;
s = splclock();
if (modes & MOD_FREQUENCY)
#ifdef PPS_SYNC
time_freq = ntv.freq - pps_freq;
#else /* PPS_SYNC */
time_freq = ntv.freq;
#endif /* PPS_SYNC */
if (modes & MOD_MAXERROR)
time_maxerror = ntv.maxerror;
if (modes & MOD_ESTERROR)
time_esterror = ntv.esterror;
if (modes & MOD_STATUS) {
time_status &= STA_RONLY;
time_status |= ntv.status & ~STA_RONLY;
}
if (modes & MOD_TIMECONST)
time_constant = ntv.constant;
if (modes & MOD_OFFSET)
hardupdate(ntv.offset);
/*
* Retrieve all clock variables
*/
if (time_offset < 0)
ntv.offset = -(-time_offset >> SHIFT_UPDATE);
else
ntv.offset = time_offset >> SHIFT_UPDATE;
#ifdef PPS_SYNC
ntv.freq = time_freq + pps_freq;
#else /* PPS_SYNC */
ntv.freq = time_freq;
#endif /* PPS_SYNC */
ntv.maxerror = time_maxerror;
ntv.esterror = time_esterror;
ntv.status = time_status;
ntv.constant = time_constant;
ntv.precision = time_precision;
ntv.tolerance = time_tolerance;
#ifdef PPS_SYNC
ntv.shift = pps_shift;
ntv.ppsfreq = pps_freq;
ntv.jitter = pps_jitter >> PPS_AVG;
ntv.stabil = pps_stabil;
ntv.calcnt = pps_calcnt;
ntv.errcnt = pps_errcnt;
ntv.jitcnt = pps_jitcnt;
ntv.stbcnt = pps_stbcnt;
#endif /* PPS_SYNC */
(void)splx(s);
error = copyout((caddr_t)&ntv, (caddr_t)uap->tp, sizeof(ntv));
if (!error) {
/*
* Status word error decode. See comments in
* ntp_gettime() routine.
*/
Move the "retval" (3rd) parameter from all syscall functions and put it in struct proc instead. This fixes a boatload of compiler warning, and removes a lot of cruft from the sources. I have not removed the /*ARGSUSED*/, they will require some looking at. libkvm, ps and other userland struct proc frobbing programs will need recompiled.
1997-11-06 19:29:57 +00:00
p->p_retval[0] = time_state;
Redo Kernel NTP PLL support, kernel side. This code is mostly taken from the 1.1 port (which was in turn taken from Dave Mills's kern.tar.Z example). A few significant differences: 1) ntp_gettime() is now a MIB variable rather than a system call. A few fiddles are done in libc to make it behave the same. 2) mono_time does not participate in the PLL adjustments. 3) A new interface has been defined (in <machine/clock.h>) for doing possibly machine-dependent things around the time of the clock update. This is used in Pentium kernels to disable interrupts, set `time', and reset the CPU cycle counter as quickly as possible to avoid jitter in microtime(). Measurements show an apparent resolution of a bit more than 8.14usec, which is reasonable given system-call overhead.
1994-09-18 20:40:01 +00:00
if (time_status & (STA_UNSYNC | STA_CLOCKERR))
Move the "retval" (3rd) parameter from all syscall functions and put it in struct proc instead. This fixes a boatload of compiler warning, and removes a lot of cruft from the sources. I have not removed the /*ARGSUSED*/, they will require some looking at. libkvm, ps and other userland struct proc frobbing programs will need recompiled.
1997-11-06 19:29:57 +00:00
p->p_retval[0] = TIME_ERROR;
Redo Kernel NTP PLL support, kernel side. This code is mostly taken from the 1.1 port (which was in turn taken from Dave Mills's kern.tar.Z example). A few significant differences: 1) ntp_gettime() is now a MIB variable rather than a system call. A few fiddles are done in libc to make it behave the same. 2) mono_time does not participate in the PLL adjustments. 3) A new interface has been defined (in <machine/clock.h>) for doing possibly machine-dependent things around the time of the clock update. This is used in Pentium kernels to disable interrupts, set `time', and reset the CPU cycle counter as quickly as possible to avoid jitter in microtime(). Measurements show an apparent resolution of a bit more than 8.14usec, which is reasonable given system-call overhead.
1994-09-18 20:40:01 +00:00
if (time_status & (STA_PPSFREQ | STA_PPSTIME) &&
!(time_status & STA_PPSSIGNAL))
Move the "retval" (3rd) parameter from all syscall functions and put it in struct proc instead. This fixes a boatload of compiler warning, and removes a lot of cruft from the sources. I have not removed the /*ARGSUSED*/, they will require some looking at. libkvm, ps and other userland struct proc frobbing programs will need recompiled.
1997-11-06 19:29:57 +00:00
p->p_retval[0] = TIME_ERROR;
Redo Kernel NTP PLL support, kernel side. This code is mostly taken from the 1.1 port (which was in turn taken from Dave Mills's kern.tar.Z example). A few significant differences: 1) ntp_gettime() is now a MIB variable rather than a system call. A few fiddles are done in libc to make it behave the same. 2) mono_time does not participate in the PLL adjustments. 3) A new interface has been defined (in <machine/clock.h>) for doing possibly machine-dependent things around the time of the clock update. This is used in Pentium kernels to disable interrupts, set `time', and reset the CPU cycle counter as quickly as possible to avoid jitter in microtime(). Measurements show an apparent resolution of a bit more than 8.14usec, which is reasonable given system-call overhead.
1994-09-18 20:40:01 +00:00
if (time_status & STA_PPSTIME &&
time_status & STA_PPSJITTER)
Move the "retval" (3rd) parameter from all syscall functions and put it in struct proc instead. This fixes a boatload of compiler warning, and removes a lot of cruft from the sources. I have not removed the /*ARGSUSED*/, they will require some looking at. libkvm, ps and other userland struct proc frobbing programs will need recompiled.
1997-11-06 19:29:57 +00:00
p->p_retval[0] = TIME_ERROR;
Redo Kernel NTP PLL support, kernel side. This code is mostly taken from the 1.1 port (which was in turn taken from Dave Mills's kern.tar.Z example). A few significant differences: 1) ntp_gettime() is now a MIB variable rather than a system call. A few fiddles are done in libc to make it behave the same. 2) mono_time does not participate in the PLL adjustments. 3) A new interface has been defined (in <machine/clock.h>) for doing possibly machine-dependent things around the time of the clock update. This is used in Pentium kernels to disable interrupts, set `time', and reset the CPU cycle counter as quickly as possible to avoid jitter in microtime(). Measurements show an apparent resolution of a bit more than 8.14usec, which is reasonable given system-call overhead.
1994-09-18 20:40:01 +00:00
if (time_status & STA_PPSFREQ &&
time_status & (STA_PPSWANDER | STA_PPSERROR))
Move the "retval" (3rd) parameter from all syscall functions and put it in struct proc instead. This fixes a boatload of compiler warning, and removes a lot of cruft from the sources. I have not removed the /*ARGSUSED*/, they will require some looking at. libkvm, ps and other userland struct proc frobbing programs will need recompiled.
1997-11-06 19:29:57 +00:00
p->p_retval[0] = TIME_ERROR;
Redo Kernel NTP PLL support, kernel side. This code is mostly taken from the 1.1 port (which was in turn taken from Dave Mills's kern.tar.Z example). A few significant differences: 1) ntp_gettime() is now a MIB variable rather than a system call. A few fiddles are done in libc to make it behave the same. 2) mono_time does not participate in the PLL adjustments. 3) A new interface has been defined (in <machine/clock.h>) for doing possibly machine-dependent things around the time of the clock update. This is used in Pentium kernels to disable interrupts, set `time', and reset the CPU cycle counter as quickly as possible to avoid jitter in microtime(). Measurements show an apparent resolution of a bit more than 8.14usec, which is reasonable given system-call overhead.
1994-09-18 20:40:01 +00:00
}
return error;
}
Reference in New Issue Copy Permalink