All,
This patch stops ntp_advance() from returning unit adjustments (ie:
nanoseconds). Instead the update_wall_time() function uses the ppm
adjustment from get_ntp_adjustment() which is then converted into a
nanosecond adjustment value.
Any comments or feedback would be greatly appreciated.
thanks
-john
linux-2.6.13-rc3_timeofday-ntp-part12_B4.patch
============================================
diff --git a/include/linux/ntp.h b/include/linux/ntp.h
--- a/include/linux/ntp.h
+++ b/include/linux/ntp.h
@@ -9,8 +9,11 @@
#include <linux/time.h>
#include <linux/timex.h>
+/* Required to safely shift negative values */
+#define shiftR(x,s) (x < 0) ? (-((-x) >> (s))) : ((x) >> (s))
+
/* NTP state machine interfaces */
-int ntp_advance(unsigned long interval_nsec);
+void ntp_advance(unsigned long interval_nsec);
int ntp_adjtimex(struct timex*);
int ntp_leapsecond(struct timespec now);
void ntp_clear(void);
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 ([EMAIL PROTECTED])
+*
+* 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 */
@@ -82,13 +82,9 @@ static seqlock_t ntp_lock = SEQLOCK_UNLO
#define MAX_SINGLESHOT_ADJ 500 /* (ppm) */
#define SEC_PER_DAY 86400
-/* Required to safely shift negative values */
-#define shiftR(x,s) (x < 0) ? (-((-x) >> (s))) : ((x) >> (s))
-
-int ntp_advance(unsigned long interval_nsec)
+void ntp_advance(unsigned long interval_nsec)
{
static unsigned long interval_sum = 0;
- long time_adjust_step, delta_nsec;
unsigned long flags;
static long ss_adj = 0;
@@ -130,23 +126,6 @@ int ntp_advance(unsigned long interval_n
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));
-#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);
-#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);
-#endif
/* Set ss_adj for the next second */
ss_adj = min_t(unsigned long, singleshot_adj,
MAX_SINGLESHOT_ADJ);
singleshot_adj -= ss_adj;
@@ -158,42 +137,6 @@ int ntp_advance(unsigned long interval_n
shifted_ppm_sum += ntp_freq; /* already shifted by SHIFT_USEC */
shifted_ppm_sum += ss_adj << SHIFT_USEC;
-
- if ( (time_adjust_step = ntp_adjtime_offset) != 0 ) {
- /* We are doing an adjtime thing.
- *
- * Prepare time_adjust_step to be within bounds.
- * Note that a positive ntp_adjtime_offset means we want the clock
- * to run faster.
- *
- * Limit the amount of the step to be in the range
- * -tickadj .. +tickadj
- */
- if (ntp_adjtime_offset > tickadj)
- time_adjust_step = tickadj;
- else if (ntp_adjtime_offset < -tickadj)
- time_adjust_step = -tickadj;
-
- /* Reduce by this step the amount of time left */
- ntp_adjtime_offset -= time_adjust_step;
- }
- delta_nsec = time_adjust_step * 1000;
-
- /*
- * Advance the phase, once it gets to one microsecond, then
- * advance the tick more.
- */
- time_phase += time_adj;
- if (time_phase <= -FINENSEC) {
- long ltemp = -time_phase >> (SHIFT_SCALE - 10);
- time_phase += ltemp << (SHIFT_SCALE - 10);
- delta_nsec -= ltemp;
- } else if (time_phase >= FINENSEC) {
- long ltemp = time_phase >> (SHIFT_SCALE - 10);
- time_phase -= ltemp << (SHIFT_SCALE - 10);
- delta_nsec += ltemp;
- }
-
/* Changes by adjtime() do not take effect till next tick. */
if (ntp_next_adjtime_offset != 0) {
ntp_adjtime_offset = ntp_next_adjtime_offset;
@@ -201,7 +144,6 @@ int ntp_advance(unsigned long interval_n
}
write_sequnlock_irqrestore(&ntp_lock, flags);
- return delta_nsec;
}
/**
diff --git a/kernel/timer.c b/kernel/timer.c
--- a/kernel/timer.c
+++ b/kernel/timer.c
@@ -598,17 +598,23 @@ struct timespec wall_to_monotonic __attr
EXPORT_SYMBOL(xtime);
-
/* in the NTP reference this is called "hardclock()" */
static void update_wall_time_one_tick(void)
{
- long delta_nsec;
+ long delta_nsec, ppm;
+ unsigned long interval_nsec;
+
+ interval_nsec = tick_nsec;
+ ppm = ntp_get_adjustment();
- delta_nsec = tick_nsec + ntp_advance(tick_nsec);
+ delta_nsec = interval_nsec;
+ delta_nsec += shiftR((interval_nsec * ppm),SHIFT_USEC)/1000000;
xtime.tv_nsec += delta_nsec;
- time_interpolator_update(delta_nsec);
+ ntp_advance(interval_nsec);
+
+ time_interpolator_update(delta_nsec);
}
/*
-
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