[PATCH] Remove obsolete CLOCK_TICK_ADJUST

Roman Zippel
2008-02-29T04:49:54Z

Hi,

Can we please clean up the current mess and get the patch below merged?

bye, Roman

Revert bbe4d18ac2e058c56adb0cd71f49d9ed3216a405 and
e13a2e61dd5152f5499d2003470acf9c838eab84 and remove CLOCK_TICK_ADJUST
completely. Add a optional kernel parameter ntp_tick_adj instead to allow
adjusting of a large base drift and thus keeping ntpd happy.
The CLOCK_TICK_ADJUST mechanism was introduced at a time PIT was the
primary clock, but we have a varity of clock sources now, so a global PIT
specific adjustment makes little sense anymore.

Signed-off-by: Roman Zippel <zippel@linux-m68k.org>

---
include/linux/timex.h | 9 +--------
kernel/time/ntp.c | 11 ++++++++++-
kernel/time/timekeeping.c | 6 ++----
3 files changed, 13 insertions(+), 13 deletions(-)

Index: linux-2.6/include/linux/timex.h
===================================================================
--- linux-2.6.orig/include/linux/timex.h
+++ linux-2.6/include/linux/timex.h
@@ -232,14 +232,7 @@ static inline int ntp_synced(void)
#else
#define NTP_INTERVAL_FREQ (HZ)
#endif
-
-#define CLOCK_TICK_OVERFLOW (LATCH * HZ - CLOCK_TICK_RATE)
-#define CLOCK_TICK_ADJUST (((s64)CLOCK_TICK_OVERFLOW * NSEC_PER_SEC) / \
- (s64)CLOCK_TICK_RATE)
-
-/* Because using NSEC_PER_SEC would be too easy */
-#define NTP_INTERVAL_LENGTH ((((s64)TICK_USEC * NSEC_PER_USEC * USER_HZ) + \
- CLOCK_TICK_ADJUST) / NTP_INTERVAL_FREQ)
+#define NTP_INTERVAL_LENGTH (NSEC_PER_SEC/NTP_INTERVAL_FREQ)

/* Returns how long ticks are at present, in ns / 2^(SHIFT_SCALE-10). */
extern u64 current_tick_length(void);
Index: linux-2.6/kernel/time/ntp.c
===================================================================
--- linux-2.6.orig/kernel/time/ntp.c
+++ linux-2.6/kernel/time/ntp.c
@@ -42,12 +42,13 @@ long time_esterror = NTP_PHASE_LIMIT; /*
long time_freq; /* frequency offset (scaled ppm)*/
static long time_reftime; /* time at last adjustment (s) */
long time_adjust;
+long ntp_tick_adj;

static void ntp_update_frequency(void)
{
u64 second_length = (u64)(tick_usec * NSEC_PER_USEC * USER_HZ)
<< TICK_LENGTH_SHIFT;
- second_length += (s64)CLOCK_TICK_ADJUST << TICK_LENGTH_SHIFT;
+ second_length += (s64)ntp_tick_adj << TICK_LENGTH_SHIFT;
second_length += (s64)time_freq << (TICK_LENGTH_SHIFT - SHIFT_NSEC);

tick_length_base = second_length;
@@ -400,3 +401,11 @@ leave: if ((time_status & (STA_UNSYNC|ST
notify_cmos_timer();
return(result);
}
+
+static int __init ntp_tick_adj_setup(char *str)
+{
+ ntp_tick_adj = simple_strtol(str, NULL, 0);
+ return 1;
+}
+
+__setup("ntp_tick_adj=", ntp_tick_adj_setup);
Index: linux-2.6/kernel/time/timekeeping.c
===================================================================
--- linux-2.6.orig/kernel/time/timekeeping.c
+++ linux-2.6/kernel/time/timekeeping.c
@@ -187,8 +187,7 @@ static void change_clocksource(void)

clock->error = 0;
clock->xtime_nsec = 0;
- clocksource_calculate_interval(clock,
- (unsigned long)(current_tick_length()>>TICK_LENGTH_SHIFT));
+ clocksource_calculate_interval(clock, NTP_INTERVAL_LENGTH);

tick_clock_notify();

@@ -245,8 +244,7 @@ void __init timekeeping_init(void)
ntp_clear();

clock = clocksource_get_next();
- clocksource_calculate_interval(clock,
- (unsigned long)(current_tick_length()>>TICK_LENGTH_SHIFT));
+ clocksource_calculate_interval(clock, NTP_INTERVAL_LENGTH);
clock->cycle_last = clocksource_read(clock);

xtime.tv_sec = sec;