The patch titled
ntp: convert to the NTP4 reference model
has been added to the -mm tree. Its filename is
ntp-convert-to-the-ntp4-reference-model.patch
See http://www.zip.com.au/~akpm/linux/patches/stuff/added-to-mm.txt to find
out what to do about this
------------------------------------------------------
Subject: ntp: convert to the NTP4 reference model
From: Roman Zippel <zippel@xxxxxxxxxxxxxx>
This converts the kernel ntp model into a model which matches the nanokernel
reference implementations. The previous patches already increased the
resolution and precision of the computations, so that this conversion becomes
quite simple.
Signed-off-by: Roman Zippel <zippel@xxxxxxxxxxxxxx>
Cc: john stultz <johnstul@xxxxxxxxxx>
Signed-off-by: Andrew Morton <akpm@xxxxxxxx>
---
include/linux/timex.h | 11 +++-----
kernel/time/ntp.c | 51 ++++++++++++++--------------------------
2 files changed, 24 insertions(+), 38 deletions(-)
diff -puN include/linux/timex.h~ntp-convert-to-the-ntp4-reference-model include/linux/timex.h
--- a/include/linux/timex.h~ntp-convert-to-the-ntp4-reference-model
+++ a/include/linux/timex.h
@@ -70,10 +70,9 @@
* zero to MAXTC, the PLL will converge in 15 minutes to 16 hours,
* respectively.
*/
-#define SHIFT_KG 6 /* phase factor (shift) */
-#define SHIFT_KF 16 /* PLL frequency factor (shift) */
-#define SHIFT_KH 2 /* FLL frequency factor (shift) */
-#define MAXTC 6 /* maximum time constant (shift) */
+#define SHIFT_PLL 4 /* PLL frequency factor (shift) */
+#define SHIFT_FLL 2 /* FLL frequency factor (shift) */
+#define MAXTC 10 /* maximum time constant (shift) */
/*
* The SHIFT_SCALE define establishes the decimal point of the time_phase
@@ -98,8 +97,8 @@
#define MAXPHASE 512000L /* max phase error (us) */
#define MAXFREQ (512L << SHIFT_USEC) /* max frequency error (ppm) */
#define MAXFREQ_NSEC (512000L << SHIFT_NSEC) /* max frequency error (ppb) */
-#define MINSEC 16L /* min interval between updates (s) */
-#define MAXSEC 1200L /* max interval between updates (s) */
+#define MINSEC 256 /* min interval between updates (s) */
+#define MAXSEC 2048 /* max interval between updates (s) */
#define NTP_PHASE_LIMIT (MAXPHASE << 5) /* beyond max. dispersion */
/*
diff -puN kernel/time/ntp.c~ntp-convert-to-the-ntp4-reference-model kernel/time/ntp.c
--- a/kernel/time/ntp.c~ntp-convert-to-the-ntp4-reference-model
+++ a/kernel/time/ntp.c
@@ -151,18 +151,11 @@ void second_overflow(void)
}
/*
- * Compute the phase adjustment for the next second. In PLL mode, the
- * offset is reduced by a fixed factor times the time constant. In FLL
- * mode the offset is used directly. In either mode, the maximum phase
- * adjustment for each second is clamped so as to spread the adjustment
- * over not more than the number of seconds between updates.
+ * Compute the phase adjustment for the next second. The offset is
+ * reduced by a fixed factor times the time constant.
*/
tick_length = tick_length_base;
- time_adj = time_offset;
- if (!(time_status & STA_FLL))
- time_adj = shift_right(time_adj, SHIFT_KG + time_constant);
- time_adj = min(time_adj, -((MAXPHASE / HZ) << SHIFT_UPDATE) / MINSEC);
- time_adj = max(time_adj, ((MAXPHASE / HZ) << SHIFT_UPDATE) / MINSEC);
+ time_adj = shift_right(time_offset, SHIFT_PLL + time_constant);
time_offset -= time_adj;
tick_length += (s64)time_adj << (TICK_LENGTH_SHIFT - SHIFT_UPDATE);
@@ -206,7 +199,7 @@ void __attribute__ ((weak)) notify_arch_
int do_adjtimex(struct timex *txc)
{
long ltemp, mtemp, save_adjust;
- s64 freq_adj;
+ s64 freq_adj, temp64;
int result;
/* In order to modify anything, you gotta be super-user! */
@@ -276,7 +269,7 @@ int do_adjtimex(struct timex *txc)
result = -EINVAL;
goto leave;
}
- time_constant = txc->constant;
+ time_constant = min(txc->constant + 4, (long)MAXTC);
}
if (txc->modes & ADJ_OFFSET) { /* values checked earlier */
@@ -304,26 +297,20 @@ int do_adjtimex(struct timex *txc)
time_reftime = xtime.tv_sec;
mtemp = xtime.tv_sec - time_reftime;
time_reftime = xtime.tv_sec;
- freq_adj = 0;
- if (time_status & STA_FLL) {
- if (mtemp >= MINSEC) {
- freq_adj = (s64)time_offset << (SHIFT_NSEC - SHIFT_KH);
- if (time_offset < 0) {
- freq_adj = -freq_adj;
- do_div(freq_adj, mtemp);
- freq_adj = -freq_adj;
- } else
- do_div(freq_adj, mtemp);
- } else /* calibration interval too short (p. 12) */
- result = TIME_ERROR;
- } else { /* PLL mode */
- if (mtemp < MAXSEC) {
- freq_adj = (s64)ltemp * mtemp;
- freq_adj = shift_right(freq_adj,(time_constant +
- time_constant +
- SHIFT_KF - SHIFT_NSEC));
- } else /* calibration interval too long (p. 12) */
- result = TIME_ERROR;
+
+ freq_adj = (s64)time_offset * mtemp;
+ freq_adj = shift_right(freq_adj, time_constant * 2 +
+ (SHIFT_PLL + 2) * 2 - SHIFT_NSEC);
+ if (mtemp >= MINSEC && (time_status & STA_FLL || mtemp > MAXSEC)) {
+ temp64 = (s64)time_offset << (SHIFT_NSEC - SHIFT_FLL);
+ if (time_offset < 0) {
+ temp64 = -temp64;
+ do_div(temp64, mtemp);
+ freq_adj -= temp64;
+ } else {
+ do_div(temp64, mtemp);
+ freq_adj += temp64;
+ }
}
freq_adj += time_freq;
freq_adj = min(freq_adj, (s64)MAXFREQ_NSEC);
_
Patches currently in -mm which might be from zippel@xxxxxxxxxxxxxx are
git-lxdialog.patch
make-prot_write-imply-prot_read.patch
ntp-move-all-the-ntp-related-code-to-ntpc.patch
ntp-add-ntp_update_frequency.patch
ntp-add-time_adj-to-tick-length.patch
ntp-add-time_freq-to-tick-length.patch
ntp-prescale-time_offset.patch
ntp-add-time_adjust-to-tick-length.patch
ntp-remove-time_tolerance.patch
ntp-convert-time_freq-to-nsec-value.patch
ntp-convert-to-the-ntp4-reference-model.patch
ntp-cleanup-defines-and-comments.patch
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