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.
70 lines
2.9 KiB
C
70 lines
2.9 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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Private include file for local.c and all system dependent
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driver modules.
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*/
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#ifndef GOT_LOCALP_H
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#define GOT_LOCALP_H
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/* System driver to read the current local frequency, in ppm relative
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to nominal. A positive value indicates that the local clock runs
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fast when uncompensated. */
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typedef double (*lcl_ReadFrequencyDriver)(void);
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/* System driver to set the current local frequency, in ppm relative
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to nominal. A positive value indicates that the local clock runs
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fast when uncompensated. Return actual frequency (may be different
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from the requested frequency due to clamping or rounding). */
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typedef double (*lcl_SetFrequencyDriver)(double freq_ppm);
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/* System driver to accrue an offset. A positive argument means slew
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the clock forwards. The suggested correction rate of time to correct the
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offset is given in 'corr_rate'. */
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typedef void (*lcl_AccrueOffsetDriver)(double offset, double corr_rate);
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/* System driver to apply a step offset. A positive argument means step
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the clock forwards. */
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typedef void (*lcl_ApplyStepOffsetDriver)(double offset);
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/* System driver to convert a raw time to an adjusted (cooked) time.
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The number of seconds returned in 'corr' have to be added to the
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raw time to get the corrected time */
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typedef void (*lcl_OffsetCorrectionDriver)(struct timeval *raw, double *corr, double *err);
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/* System driver to schedule leap second */
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typedef void (*lcl_SetLeapDriver)(int leap);
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extern void lcl_InvokeDispersionNotifyHandlers(double dispersion);
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extern void
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lcl_RegisterSystemDrivers(lcl_ReadFrequencyDriver read_freq,
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lcl_SetFrequencyDriver set_freq,
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lcl_AccrueOffsetDriver accrue_offset,
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lcl_ApplyStepOffsetDriver apply_step_offset,
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lcl_OffsetCorrectionDriver offset_convert,
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lcl_SetLeapDriver set_leap);
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#endif /* GOT_LOCALP_H */
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