[PATCH] ntp: add time_adjust to tick length
This folds update_ntp_one_tick() into second_overflow() and adds time_adjust
to the tick length, this makes time_next_adjust unnecessary. This slightly
changes the adjtime() behaviour, instead of applying it to the next tick, it's
applied to the next second.
Signed-off-by: Roman Zippel <zippel@linux-m68k.org>
Cc: john stultz <johnstul@us.ibm.com>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>
diff --git a/include/linux/timex.h b/include/linux/timex.h
index 1cde6f6..b5f297e 100644
--- a/include/linux/timex.h
+++ b/include/linux/timex.h
@@ -217,7 +217,6 @@
extern long time_reftime; /* time at last adjustment (s) */
extern long time_adjust; /* The amount of adjtime left */
-extern long time_next_adjust; /* Value for time_adjust at next tick */
extern void ntp_clear(void);
extern void ntp_update_frequency(void);
diff --git a/kernel/time/ntp.c b/kernel/time/ntp.c
index 238ce47..65223b7 100644
--- a/kernel/time/ntp.c
+++ b/kernel/time/ntp.c
@@ -22,8 +22,9 @@
unsigned long tick_nsec; /* ACTHZ period (nsec) */
static u64 tick_length, tick_length_base;
-/* Don't completely fail for HZ > 500. */
-int tickadj = 500/HZ ? : 1; /* microsecs */
+#define MAX_TICKADJ 500 /* microsecs */
+#define MAX_TICKADJ_SCALED (((u64)(MAX_TICKADJ * NSEC_PER_USEC) << \
+ TICK_LENGTH_SHIFT) / HZ)
/*
* phase-lock loop variables
@@ -40,7 +41,6 @@
long time_freq; /* frequency offset (scaled ppm)*/
long time_reftime; /* time at last adjustment (s) */
long time_adjust;
-long time_next_adjust;
/**
* ntp_clear - Clears the NTP state variables
@@ -160,46 +160,19 @@
time_adj = max(time_adj, ((MAXPHASE / HZ) << SHIFT_UPDATE) / MINSEC);
time_offset -= time_adj;
tick_length += (s64)time_adj << (TICK_LENGTH_SHIFT - SHIFT_UPDATE);
-}
-/*
- * Returns how many microseconds we need to add to xtime this tick
- * in doing an adjustment requested with adjtime.
- */
-static long adjtime_adjustment(void)
-{
- long time_adjust_step;
-
- time_adjust_step = time_adjust;
- if (time_adjust_step) {
- /*
- * We are doing an adjtime thing. Prepare time_adjust_step to
- * be within bounds. Note that a positive time_adjust means we
- * want the clock to run faster.
- *
- * Limit the amount of the step to be in the range
- * -tickadj .. +tickadj
- */
- time_adjust_step = min(time_adjust_step, (long)tickadj);
- time_adjust_step = max(time_adjust_step, (long)-tickadj);
- }
- return time_adjust_step;
-}
-
-/* in the NTP reference this is called "hardclock()" */
-void update_ntp_one_tick(void)
-{
- long time_adjust_step;
-
- time_adjust_step = adjtime_adjustment();
- if (time_adjust_step)
- /* Reduce by this step the amount of time left */
- time_adjust -= time_adjust_step;
-
- /* Changes by adjtime() do not take effect till next tick. */
- if (time_next_adjust != 0) {
- time_adjust = time_next_adjust;
- time_next_adjust = 0;
+ if (unlikely(time_adjust)) {
+ if (time_adjust > MAX_TICKADJ) {
+ time_adjust -= MAX_TICKADJ;
+ tick_length += MAX_TICKADJ_SCALED;
+ } else if (time_adjust < -MAX_TICKADJ) {
+ time_adjust += MAX_TICKADJ;
+ tick_length -= MAX_TICKADJ_SCALED;
+ } else {
+ time_adjust = 0;
+ tick_length += (s64)(time_adjust * NSEC_PER_USEC /
+ HZ) << TICK_LENGTH_SHIFT;
+ }
}
}
@@ -213,14 +186,7 @@
*/
u64 current_tick_length(void)
{
- u64 ret;
-
- /* calculate the finest interval NTP will allow.
- */
- ret = tick_length;
- ret += (u64)(adjtime_adjustment() * 1000) << TICK_LENGTH_SHIFT;
-
- return ret;
+ return tick_length;
}
@@ -263,7 +229,7 @@
result = time_state; /* mostly `TIME_OK' */
/* Save for later - semantics of adjtime is to return old value */
- save_adjust = time_next_adjust ? time_next_adjust : time_adjust;
+ save_adjust = time_adjust;
#if 0 /* STA_CLOCKERR is never set yet */
time_status &= ~STA_CLOCKERR; /* reset STA_CLOCKERR */
@@ -310,8 +276,7 @@
if (txc->modes & ADJ_OFFSET) { /* values checked earlier */
if (txc->modes == ADJ_OFFSET_SINGLESHOT) {
/* adjtime() is independent from ntp_adjtime() */
- if ((time_next_adjust = txc->offset) == 0)
- time_adjust = 0;
+ time_adjust = txc->offset;
}
else if (time_status & STA_PLL) {
ltemp = txc->offset;
diff --git a/kernel/timer.c b/kernel/timer.c
index 78d3fa1..654dd5d 100644
--- a/kernel/timer.c
+++ b/kernel/timer.c
@@ -937,8 +937,6 @@
/* interpolator bits */
time_interpolator_update(clock->xtime_interval
>> clock->shift);
- /* increment the NTP state machine */
- update_ntp_one_tick();
/* accumulate error between NTP and clock interval */
clock->error += current_tick_length();