c7d0232bb1
We want to correct the offset quickly, but we also want to keep the frequency error caused by the correction itself low. Define correction rate as the area of the region bounded by the graph of offset corrected in time. Set the rate so that the time needed to correct an offset equal to the current sourcestats stddev will be equal to the update interval (assuming linear adjustment). The offset and the time needed to make the correction are inversely proportional. This is only a suggestion and it's up to the system driver how the adjustment will be executed.
144 lines
3.8 KiB
C
144 lines
3.8 KiB
C
/*
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chronyd/chronyc - Programs for keeping computer clocks accurate.
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**********************************************************************
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* Copyright (C) Richard P. Curnow 1997-2002
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*
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* This program is free software; you can redistribute it and/or modify
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* it under the terms of version 2 of the GNU General Public License as
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* published by the Free Software Foundation.
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*
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* This program is distributed in the hope that it will be useful, but
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* WITHOUT ANY WARRANTY; without even the implied warranty of
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* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
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* General Public License for more details.
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*
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* You should have received a copy of the GNU General Public License along
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* with this program; if not, write to the Free Software Foundation, Inc.,
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* 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301, USA.
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*
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**********************************************************************
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=======================================================================
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This is the header file for the module that keeps track of the current
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reference.
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*/
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#ifndef GOT_REFERENCE_H
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#define GOT_REFERENCE_H
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#include "sysincl.h"
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#include "ntp.h"
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#include "reports.h"
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/* Init function */
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extern void REF_Initialise(void);
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/* Fini function */
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extern void REF_Finalise(void);
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/* Function which takes a local cooked time and returns the estimated
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time of the reference. It also returns the other parameters
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required for forming the outgoing NTP packet.
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local_time is the cooked local time returned by the LCL module
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is_synchronised indicates whether we are synchronised to anything
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at the moment.
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leap indicates the current leap status
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stratum is the stratum of this machine, when considered to be sync'd to the
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reference
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ref_id is the reference_id of the source
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ref_time is the time at which the we last set the reference source up
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root_delay is the root delay of the sample we are using
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root_dispersion is the root dispersion of the sample we are using, with all the
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skew etc added on.
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*/
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extern void REF_GetReferenceParams
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(
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struct timeval *local_time,
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int *is_synchronised,
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NTP_Leap *leap,
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int *stratum,
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uint32_t *ref_id,
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struct timeval *ref_time,
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double *root_delay,
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double *root_dispersion
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);
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/* Function called by the clock selection process to register a new
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reference source and its parameters
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stratum is the stratum of the reference
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leap is the leap status read from the source
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ref_id is the reference id of the reference
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ref_time is the time at which the parameters are assumed to be
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correct, in terms of local time
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frequency is the amount of local clock gain relative to the
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reference per unit time interval of the local clock
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skew is the maximum estimated frequency error (so we are within
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[frequency+-skew])
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root_delay is the root delay of the sample we are using
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root_dispersion is the root dispersion of the sample we are using
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*/
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extern void REF_SetReference
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(
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int stratum,
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NTP_Leap leap,
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uint32_t ref_id,
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IPAddr *ref_ip,
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struct timeval *ref_time,
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double offset,
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double offset_sd,
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double frequency,
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double skew,
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double root_delay,
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double root_dispersion
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);
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extern void REF_SetManualReference
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(
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struct timeval *ref_time,
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double offset,
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double frequency,
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double skew
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);
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/* Mark the local clock as unsynchronised */
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extern void
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REF_SetUnsynchronised(void);
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/* Return the current stratum of this host or zero if the host is not
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synchronised */
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extern int REF_GetOurStratum(void);
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/* Modify the setting for the maximum skew we are prepared to allow updates on (in ppm). */
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extern void REF_ModifyMaxupdateskew(double new_max_update_skew);
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extern void REF_EnableLocal(int stratum);
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extern void REF_DisableLocal(void);
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extern int REF_IsLocalActive(void);
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extern void REF_GetTrackingReport(RPT_TrackingReport *rep);
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#endif /* GOT_REFERENCE_H */
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