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timedated: update spike handling

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This commit is contained in:
Kay Sievers
2014-03-16 23:22:21 +01:00
parent 7b41586761
commit 3dbc762003
1 changed files with 46 additions and 44 deletions
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src/timedate/timedate-sntp.c
+46 -44
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@@ -133,10 +133,10 @@ struct SNTPContext {
/* poll timer */
sd_event_source *event_timer;
usec_t poll_interval;
usec_t poll_interval_usec;
bool poll_resync;
/* statistics data */
/* history data */
struct {
double offset;
double delay;
@@ -347,7 +347,7 @@ static int sntp_adjust_clock(SNTPContext *sntp, double offset, int leap_sec) {
if (offset < NTP_MAX_ADJUST && offset > -NTP_MAX_ADJUST) {
int constant;
constant = log2i(sntp->poll_interval / USEC_PER_SEC) - 5;
constant = log2i(sntp->poll_interval_usec / USEC_PER_SEC) - 6;
tmx.modes |= ADJ_STATUS | ADJ_OFFSET | ADJ_TIMECONST;
tmx.status = STA_PLL;
@@ -392,7 +392,7 @@ static int sntp_adjust_clock(SNTPContext *sntp, double offset, int leap_sec) {
static bool sntp_sample_spike_detection(SNTPContext *sntp, double offset, double delay) {
unsigned int i, idx_cur, idx_new, idx_min;
double jitter;
bool spike;
double j;
/* store the current data in our samples array */
idx_cur = sntp->samples_idx;
@@ -402,61 +402,62 @@ static bool sntp_sample_spike_detection(SNTPContext *sntp, double offset, double
sntp->samples[idx_new].delay = delay;
sntp->packet_count++;
jitter = sntp->samples_jitter;
/*
* Spike detection; compare the difference between the current offset to
* the previous offset and jitter.
*/
spike = !sntp->poll_resync &&
sntp->packet_count > 2 &&
fabs(offset - sntp->samples[idx_cur].offset) > sntp->samples_jitter * 3;
/* ignore samples when resyncing */
if (sntp->poll_resync)
return false;
/* we need a few samples before we calculate anything */
if (sntp->packet_count < 3)
return false;
/* always accept sample if we are farther off than the round trip delay */
if (fabs(offset) > delay)
return false;
/* calculate new jitter value from the RMS differences relative to the lowest delay sample */
for (idx_min = idx_cur, i = 0; i < ELEMENTSOF(sntp->samples); i++)
if (sntp->samples[i].delay > 0 && sntp->samples[i].delay < sntp->samples[idx_min].delay)
idx_min = i;
for (jitter = 0, i = 0; i < ELEMENTSOF(sntp->samples); i++)
jitter += square(sntp->samples[i].offset - sntp->samples[idx_min].offset);
sntp->samples_jitter = sqrt(jitter / (ELEMENTSOF(sntp->samples) - 1));
j = 0;
for (i = 0; i < ELEMENTSOF(sntp->samples); i++)
j += square(sntp->samples[i].offset - sntp->samples[idx_min].offset);
sntp->samples_jitter = sqrt(j / (ELEMENTSOF(sntp->samples) - 1));
return spike;
/* do not accept anything worse than the maximum possible error of the best sample */
if (abs(offset) > sntp->samples[idx_min].delay)
return true;
/* compare the difference between the current offset to the previous offset and jitter */
return fabs(offset - sntp->samples[idx_cur].offset) > 3 * jitter;
}
static void sntp_adjust_poll(SNTPContext *sntp, double offset, bool spike) {
double delta;
if (sntp->poll_resync) {
sntp->poll_interval = NTP_POLL_INTERVAL_MIN_SEC * USEC_PER_SEC;
sntp->poll_interval_usec = NTP_POLL_INTERVAL_MIN_SEC * USEC_PER_SEC;
sntp->poll_resync = false;
return;
}
if (spike) {
if (sntp->poll_interval > NTP_POLL_INTERVAL_MIN_SEC * USEC_PER_SEC)
sntp->poll_interval /= 2;
return;
}
delta = fabs(offset);
/* set to minimal poll interval */
if (delta > NTP_ACCURACY_SEC) {
sntp->poll_interval = NTP_POLL_INTERVAL_MIN_SEC * USEC_PER_SEC;
if (fabs(offset) > NTP_ACCURACY_SEC) {
sntp->poll_interval_usec = NTP_POLL_INTERVAL_MIN_SEC * USEC_PER_SEC;
return;
}
/* increase polling interval */
if (delta < NTP_ACCURACY_SEC * 0.25) {
if (sntp->poll_interval < NTP_POLL_INTERVAL_MAX_SEC * USEC_PER_SEC)
sntp->poll_interval *= 2;
if (fabs(offset) < NTP_ACCURACY_SEC * 0.25) {
if (sntp->poll_interval_usec < NTP_POLL_INTERVAL_MAX_SEC * USEC_PER_SEC)
sntp->poll_interval_usec *= 2;
return;
}
/* decrease polling interval */
if (delta > NTP_ACCURACY_SEC * 0.75) {
if (sntp->poll_interval > NTP_POLL_INTERVAL_MIN_SEC * USEC_PER_SEC)
sntp->poll_interval /= 2;
if (spike || fabs(offset) > NTP_ACCURACY_SEC * 0.75) {
if (sntp->poll_interval_usec > NTP_POLL_INTERVAL_MIN_SEC * USEC_PER_SEC)
sntp->poll_interval_usec /= 2;
return;
}
}
@@ -482,7 +483,7 @@ static int sntp_receive_response(sd_event_source *source, int fd, uint32_t reven
.msg_namelen = sizeof(server_addr),
};
struct cmsghdr *cmsg;
struct timespec now;
struct timespec now_ts;
struct timeval *recv_time;
ssize_t len;
struct ntp_msg *ntpmsg;
@@ -581,8 +582,8 @@ static int sntp_receive_response(sd_event_source *source, int fd, uint32_t reven
* The roundtrip delay d and system clock offset t are defined as:
* d = (T4 - T1) - (T3 - T2) t = ((T2 - T1) + (T3 - T4)) / 2"
*/
clock_gettime(CLOCK_MONOTONIC, &now);
origin = tv_to_d(recv_time) - (ts_to_d(&now) - ts_to_d(&sntp->trans_time_mon)) + OFFSET_1900_1970;
clock_gettime(CLOCK_MONOTONIC, &now_ts);
origin = tv_to_d(recv_time) - (ts_to_d(&now_ts) - ts_to_d(&sntp->trans_time_mon)) + OFFSET_1900_1970;
receive = ntp_ts_to_d(&ntpmsg->recv_time);
trans = ntp_ts_to_d(&ntpmsg->trans_time);
dest = tv_to_d(recv_time) + OFFSET_1900_1970;
@@ -608,7 +609,7 @@ static int sntp_receive_response(sd_event_source *source, int fd, uint32_t reven
" offset : %+f sec\n"
" delay : %+f sec\n"
" packet count : %"PRIu64"\n"
" jitter/spike : %f (%s)\n"
" jitter : %f%s\n"
" poll interval: %llu\n",
NTP_FIELD_LEAP(ntpmsg->field),
NTP_FIELD_VERSION(ntpmsg->field),
@@ -622,11 +623,12 @@ static int sntp_receive_response(sd_event_source *source, int fd, uint32_t reven
dest - OFFSET_1900_1970,
offset, delay,
sntp->packet_count,
sntp->samples_jitter, spike ? "yes" : "no",
sntp->poll_interval / USEC_PER_SEC);
sntp->samples_jitter, spike ? " spike" : "",
sntp->poll_interval_usec / USEC_PER_SEC);
log_info("%4llu %+10f %10f %10f %s",
sntp->poll_interval / USEC_PER_SEC, offset, delay, sntp->samples_jitter, spike ? "spike" : "");
log_info("%4llu %+10f %10f %10f%s",
sntp->poll_interval_usec / USEC_PER_SEC, offset, delay,
sntp->samples_jitter, spike ? " spike" : "");
if (!spike) {
r = sntp_adjust_clock(sntp, offset, leap_sec);
@@ -634,7 +636,7 @@ static int sntp_receive_response(sd_event_source *source, int fd, uint32_t reven
log_error("Failed to call clock_adjtime(): %m");
}
r = sntp_arm_timer(sntp, sntp->poll_interval);
r = sntp_arm_timer(sntp, sntp->poll_interval_usec);
if (r < 0)
return r;
@@ -660,7 +662,7 @@ int sntp_server_connect(SNTPContext *sntp, const char *server) {
sntp->server_addr.sin_family = AF_INET;
sntp->server_addr.sin_addr.s_addr = inet_addr(server);
sntp->poll_interval = 2 * NTP_POLL_INTERVAL_MIN_SEC * USEC_PER_SEC;
sntp->poll_interval_usec = 2 * NTP_POLL_INTERVAL_MIN_SEC * USEC_PER_SEC;
return sntp_send_request(sntp);
}