Messages in this thread Patch in this message | | | Subject | [RFC][PATCH - 13/13] NTP cleanup: drop time_phase and time_adj add copyright | From | john stultz <> | Date | Wed, 10 Aug 2005 18:38:08 -0700 |
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All, This patch replaces two global variables with better named static local variables. Additionally it adds my copyright.
Any comments or feedback would be greatly appreciated.
thanks -john
linux-2.6.13-rc6_timeofday-ntp-part13_B5.patch ============================================ diff --git a/kernel/ntp.c b/kernel/ntp.c --- a/kernel/ntp.c +++ b/kernel/ntp.c @@ -3,7 +3,9 @@ * * NTP state machine and time scaling code. * -* Code moved from kernel/time.c and kernel/timer.c +* Copyright (C) 2004, 2005 IBM, John Stultz (johnstul@us.ibm.com) +* +* Code moved and rewritten from kernel/time.c and kernel/timer.c * Please see those files for original copyrights. * * This program is free software; you can redistribute it and/or modify @@ -48,8 +50,6 @@ /* Don't completely fail for HZ > 500. */ int tickadj = 500/HZ ? : 1; /* microsecs */ -static long time_phase; /* phase offset (scaled us) */ -static long time_adj; /* tick adjust (scaled 1 / HZ) */ /* Chapter 5: Kernel Variables [RFC 1589 pg. 28] */ /* 5.1 Interface Variables */ @@ -86,9 +86,9 @@ static seqlock_t ntp_lock = SEQLOCK_UNLO void ntp_advance(unsigned long interval_nsec) { static unsigned long interval_sum = 0; - long time_adjust_step; unsigned long flags; static long ss_adj = 0; + static long phase, phase_adj = 0; write_seqlock_irqsave(&ntp_lock, flags); @@ -128,22 +128,24 @@ void ntp_advance(unsigned long interval_ ntp_offset -= next_adj; offset_adj = shiftR(next_adj, SHIFT_UPDATE); /* ppm */ - time_adj = next_adj << (SHIFT_SCALE - SHIFT_HZ - SHIFT_UPDATE); - time_adj += shiftR(ntp_freq, (SHIFT_USEC + SHIFT_HZ - SHIFT_SCALE)); + /* calculate the per tick phase adjustment for the next second */ + phase_adj = next_adj << (SHIFT_SCALE - SHIFT_HZ - SHIFT_UPDATE); + phase_adj += shiftR(ntp_freq, (SHIFT_USEC + SHIFT_HZ - SHIFT_SCALE)); #if HZ == 100 /* Compensate for (HZ==100) != (1 << SHIFT_HZ). * Add 25% and 3.125% to get 128.125; * => only 0.125% error (p. 14) */ - time_adj += shiftR(time_adj,2) + shiftR(time_adj,5); + phase_adj += shiftR(phase_adj,2) + shiftR(phase_adj,5); #endif #if HZ == 1000 /* Compensate for (HZ==1000) != (1 << SHIFT_HZ). * Add 1.5625% and 0.78125% to get 1023.4375; * => only 0.05% error (p. 14) */ - time_adj += shiftR(time_adj,6) + shiftR(time_adj,7); + phase_adj += shiftR(phase_adj,6) + shiftR(phase_adj,7); #endif + /* Set ss_adj for the next second */ ss_adj = min_t(unsigned long, singleshot_adj, MAX_SINGLESHOT_ADJ); singleshot_adj -= ss_adj; @@ -176,14 +178,14 @@ void ntp_advance(unsigned long interval_ * Advance the phase, once it gets to one nanosecond, * then advance the fixed_tick_ns_adj. */ - time_phase += time_adj; - if (time_phase <= -FINENSEC) { - long ltemp = -time_phase >> (SHIFT_SCALE - 10); - time_phase += ltemp << (SHIFT_SCALE - 10); + phase += phase_adj; + if (phase <= -FINENSEC) { + long ltemp = -phase >> (SHIFT_SCALE - 10); + phase += ltemp << (SHIFT_SCALE - 10); fixed_tick_ns_adj -= ltemp; - } else if (time_phase >= FINENSEC) { - long ltemp = time_phase >> (SHIFT_SCALE - 10); - time_phase -= ltemp << (SHIFT_SCALE - 10); + } else if (phase >= FINENSEC) { + long ltemp = phase >> (SHIFT_SCALE - 10); + phase -= ltemp << (SHIFT_SCALE - 10); fixed_tick_ns_adj += ltemp; }
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