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61313117a

Denys Vlasenko
Denys Vlasenko
2010-01-01
FAILED Duration: 36s

Subject

ntpd: disable unused code; show kernel's clock drift correction

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Architecture & Compiler Flags

Architecture: x86_64-linux-gnu Compiler: gcc (Ubuntu 11.4.0-1ubuntu1~22.04.3) 11.4.0

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Commit Diff GitHub →

networking/ntpd.c +38 -24
networking/ntpd.c+38 -24
@@ -43,13 +43,13 @@
* max 5 is very talkative (and bloated). 2 is non-bloated,
* production level setting.
*/
-#define MAX_VERBOSE 2
+#define MAX_VERBOSE 2
#define RETRY_INTERVAL 5 /* on error, retry in N secs */
#define QUERYTIME_MAX 15 /* wait for reply up to N secs */
-#define FREQ_TOLERANCE 15e-6 /* % frequency tolerance (15 PPM) */
+#define FREQ_TOLERANCE 0.000015 /* % frequency tolerance (15 PPM) */
#define MINPOLL 4 /* % minimum poll interval (6: 64 s) */
#define MAXPOLL 12 /* % maximum poll interval (12: 1.1h, 17: 36.4h) (was 17) */
#define MINDISP 0.01 /* % minimum dispersion (s) */
@@ -59,34 +59,35 @@
#define MIN_SELECTED 1 /* % minimum intersection survivors */
#define MIN_CLUSTERED 3 /* % minimum cluster survivors */
-#define MAXFREQ 0.000500 /* frequency tolerance (500 PPM) */
+#define MAXDRIFT 0.000500 /* frequency drift we can correct (500 PPM) */
/* Clock discipline parameters and constants */
#define STEP_THRESHOLD 0.128 /* step threshold (s) */
-#define WATCH_THRESHOLD 150 /* stepout threshold (s). std ntpd uses 900 (11 mins (!)) */
+#define WATCH_THRESHOLD 150 /* stepout threshold (s). std ntpd uses 900 (11 mins (!)) */
/* NB: set WATCH_THRESHOLD to ~60 when debugging to save time) */
#define PANIC_THRESHOLD 1000 /* panic threshold (s) */
/* Poll-adjust threshold.
* When we see that offset is small enough compared to discipline jitter,
* we grow a counter: += MINPOLL. When it goes over POLLADJ_LIMIT,
- * we poll_ext++. If offset isn't small, counter -= poll_ext*2,
- * and when it goes below -POLLADJ_LIMIT, we poll_ext--
+ * we poll_exp++. If offset isn't small, counter -= poll_exp*2,
+ * and when it goes below -POLLADJ_LIMIT, we poll_exp--
*/
-#define POLLADJ_LIMIT 30
+#define POLLADJ_LIMIT 30
/* If offset < POLLADJ_GATE * discipline_jitter, then we can increase
* poll interval (we think we can't improve timekeeping
* by staying at smaller poll).
*/
-#define POLLADJ_GATE 4
+#define POLLADJ_GATE 4
/* Compromise Allan intercept (s). doc uses 1500, std ntpd uses 512 */
-#define ALLAN 512
+#define ALLAN 512
/* PLL loop gain */
-#define PLL 65536
+#define PLL 65536
/* FLL loop gain [why it depends on MAXPOLL??] */
-#define FLL (MAXPOLL + 1)
+#define FLL (MAXPOLL + 1)
/* Parameter averaging constant */
-#define AVG 4
+#define AVG 4
+
enum {
NTP_VERSION = 4,
@@ -251,13 +252,17 @@ struct globals {
uint8_t discipline_state; // doc calls it c.state
uint8_t poll_exp; // s.poll
int polladj_count; // c.count
- double discipline_jitter; // c.jitter
+ long kernel_freq_drift;
double last_update_offset; // c.last
+ double last_update_recv_time; // s.t
+ double discipline_jitter; // c.jitter
+//TODO: add s.jitter - grep for it here and see clock_combine() in doc
+#define USING_KERNEL_PLL_LOOP 1
+#if !USING_KERNEL_PLL_LOOP
double discipline_freq_drift; // c.freq
//TODO: conditionally calculate wander? it's used only for logging
double discipline_wander; // c.wander
- double last_update_recv_time; // s.t
-//TODO: add s.jitter - grep for it here and see clock_combine() in doc
+#endif
};
#define G (*ptr_to_globals)
@@ -1153,25 +1158,27 @@ update_local_clock(peer_t *p, double t)
* (Any other state does not reach this, they all return earlier)
* By this time, freq_drift and G.last_update_offset are set
* to values suitable for adjtimex.
- *
- * Calculate the new frequency drift and frequency stability (wander).
+ */
+#if !USING_KERNEL_PLL_LOOP
+ /* Calculate the new frequency drift and frequency stability (wander).
* Compute the clock wander as the RMS of exponentially weighted
* frequency differences. This is not used directly, but can,
* along with the jitter, be a highly useful monitoring and
* debugging tool.
*/
dtemp = G.discipline_freq_drift + freq_drift;
- G.discipline_freq_drift = MAXD(MIND(MAXFREQ, dtemp), -MAXFREQ);
+ G.discipline_freq_drift = MAXD(MIND(MAXDRIFT, dtemp), -MAXDRIFT);
etemp = SQUARE(G.discipline_wander);
dtemp = SQUARE(dtemp);
G.discipline_wander = SQRT(etemp + (dtemp - etemp) / AVG);
+ VERB3 bb_error_msg("discipline freq_drift=%.9f(int:%ld corr:%e) wander=%f",
+ G.discipline_freq_drift,
+ (long)(G.discipline_freq_drift * 65536e6),
+ freq_drift,
+ G.discipline_wander);
+#endif
VERB3 {
- bb_error_msg("discipline freq_drift=%.9f(int:%ld corr:%e) wander=%f",
- G.discipline_freq_drift,
- (long)(G.discipline_freq_drift * 65536e6),
- freq_drift,
- G.discipline_wander);
memset(&tmx, 0, sizeof(tmx));
if (adjtimex(&tmx) < 0)
bb_perror_msg_and_die("adjtimex");
@@ -1192,7 +1199,7 @@ update_local_clock(peer_t *p, double t)
}
memset(&tmx, 0, sizeof(tmx));
#if 0
-//doesn't work, offset remains 0 (!):
+//doesn't work, offset remains 0 (!) in kernel:
//ntpd: set adjtimex freq:1786097 tmx.offset:77487
//ntpd: prev adjtimex freq:1786097 tmx.offset:0
//ntpd: cur adjtimex freq:1786097 tmx.offset:0
@@ -1218,14 +1225,21 @@ update_local_clock(peer_t *p, double t)
rc = adjtimex(&tmx);
if (rc < 0)
bb_perror_msg_and_die("adjtimex");
+ if (G.kernel_freq_drift != tmx.freq / 65536) {
+ G.kernel_freq_drift = tmx.freq / 65536;
+ VERB2 bb_error_msg("kernel clock drift: %ld ppm", G.kernel_freq_drift);
+ }
VERB3 {
bb_error_msg("adjtimex:%d freq:%ld offset:%ld constant:%ld status:0x%x",
rc, tmx.freq, tmx.offset, tmx.constant, tmx.status);
+#if 0
+ /* always gives the same output as above msg */
memset(&tmx, 0, sizeof(tmx));
if (adjtimex(&tmx) < 0)
bb_perror_msg_and_die("adjtimex");
VERB3 bb_error_msg("c adjtimex freq:%ld offset:%ld constant:%ld status:0x%x",
tmx.freq, tmx.offset, tmx.constant, tmx.status);
+#endif
}
// #define STA_MODE 0x4000 /* mode (0 = PLL, 1 = FLL) (ro) */ - ?
// it appeared after a while: