[PATCH] ntp: add ntp_update_frequency
This introduces ntp_update_frequency() and deinlines ntp_clear() (as it's not
performance critical). ntp_update_frequency() calculates the base tick length
using tick_usec and adds a base adjustment, in case the frequency doesn't
divide evenly by HZ.
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 2a21485..b589c82 100644
--- a/include/linux/timex.h
+++ b/include/linux/timex.h
@@ -219,18 +219,8 @@
extern long time_adjust; /* The amount of adjtime left */
extern long time_next_adjust; /* Value for time_adjust at next tick */
-/**
- * ntp_clear - Clears the NTP state variables
- *
- * Must be called while holding a write on the xtime_lock
- */
-static inline void ntp_clear(void)
-{
- time_adjust = 0; /* stop active adjtime() */
- time_status |= STA_UNSYNC;
- time_maxerror = NTP_PHASE_LIMIT;
- time_esterror = NTP_PHASE_LIMIT;
-}
+extern void ntp_clear(void);
+extern void ntp_update_frequency(void);
/**
* ntp_synced - Returns 1 if the NTP status is not UNSYNC
diff --git a/kernel/time/ntp.c b/kernel/time/ntp.c
index 8ccce15..77137be 100644
--- a/kernel/time/ntp.c
+++ b/kernel/time/ntp.c
@@ -15,6 +15,13 @@
#include <asm/div64.h>
#include <asm/timex.h>
+/*
+ * Timekeeping variables
+ */
+unsigned long tick_usec = TICK_USEC; /* USER_HZ period (usec) */
+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 */
@@ -37,6 +44,36 @@
long time_adjust;
long time_next_adjust;
+/**
+ * ntp_clear - Clears the NTP state variables
+ *
+ * Must be called while holding a write on the xtime_lock
+ */
+void ntp_clear(void)
+{
+ time_adjust = 0; /* stop active adjtime() */
+ time_status |= STA_UNSYNC;
+ time_maxerror = NTP_PHASE_LIMIT;
+ time_esterror = NTP_PHASE_LIMIT;
+
+ ntp_update_frequency();
+
+ tick_length = tick_length_base;
+}
+
+#define CLOCK_TICK_OVERFLOW (LATCH * HZ - CLOCK_TICK_RATE)
+#define CLOCK_TICK_ADJUST (((s64)CLOCK_TICK_OVERFLOW * NSEC_PER_SEC) / (s64)CLOCK_TICK_RATE)
+
+void ntp_update_frequency(void)
+{
+ tick_length_base = (u64)(tick_usec * NSEC_PER_USEC * USER_HZ) << TICK_LENGTH_SHIFT;
+ tick_length_base += (s64)CLOCK_TICK_ADJUST << TICK_LENGTH_SHIFT;
+
+ do_div(tick_length_base, HZ);
+
+ tick_nsec = tick_length_base >> TICK_LENGTH_SHIFT;
+}
+
/*
* this routine handles the overflow of the microsecond field
*
@@ -151,6 +188,7 @@
*/
time_adj += shift_right(time_adj, 6) + shift_right(time_adj, 7);
#endif
+ tick_length = tick_length_base;
}
/*
@@ -204,14 +242,13 @@
*/
u64 current_tick_length(void)
{
- long delta_nsec;
u64 ret;
/* calculate the finest interval NTP will allow.
* ie: nanosecond value shifted by (SHIFT_SCALE - 10)
*/
- delta_nsec = tick_nsec + adjtime_adjustment() * 1000;
- ret = (u64)delta_nsec << TICK_LENGTH_SHIFT;
+ ret = tick_length;
+ ret += (u64)(adjtime_adjustment() * 1000) << TICK_LENGTH_SHIFT;
ret += (s64)time_adj << (TICK_LENGTH_SHIFT - (SHIFT_SCALE - 10));
return ret;
@@ -351,10 +388,11 @@
time_freq = max(time_freq, -time_tolerance);
} /* STA_PLL */
} /* txc->modes & ADJ_OFFSET */
- if (txc->modes & ADJ_TICK) {
+ if (txc->modes & ADJ_TICK)
tick_usec = txc->tick;
- tick_nsec = TICK_USEC_TO_NSEC(tick_usec);
- }
+
+ if (txc->modes & ADJ_TICK)
+ ntp_update_frequency();
} /* txc->modes */
leave: if ((time_status & (STA_UNSYNC|STA_CLOCKERR)) != 0)
result = TIME_ERROR;
diff --git a/kernel/timer.c b/kernel/timer.c
index 5fccc7c..78d3fa1 100644
--- a/kernel/timer.c
+++ b/kernel/timer.c
@@ -562,12 +562,6 @@
/******************************************************************/
-/*
- * Timekeeping variables
- */
-unsigned long tick_usec = TICK_USEC; /* USER_HZ period (usec) */
-unsigned long tick_nsec = TICK_NSEC; /* ACTHZ period (nsec) */
-
/*
* The current time
* wall_to_monotonic is what we need to add to xtime (or xtime corrected
@@ -757,10 +751,13 @@
unsigned long flags;
write_seqlock_irqsave(&xtime_lock, flags);
+
+ ntp_clear();
+
clock = clocksource_get_next();
clocksource_calculate_interval(clock, tick_nsec);
clock->cycle_last = clocksource_read(clock);
- ntp_clear();
+
write_sequnlock_irqrestore(&xtime_lock, flags);
}