ntpd: fix jitter calculations and status propagation
Signed-off-by: Denys Vlasenko <vda.linux@googlemail.com>
This commit is contained in:
Denys Vlasenko
parent
f25252c69e
commit
1ee5afdce2
@ -166,7 +166,7 @@ typedef struct {
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int p_fd;
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int datapoint_idx;
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uint32_t lastpkt_refid;
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uint8_t lastpkt_leap;
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uint8_t lastpkt_status;
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uint8_t lastpkt_stratum;
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uint8_t p_reachable_bits;
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double p_xmttime;
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@ -216,7 +216,7 @@ struct globals {
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* in stratum 2+ packets, it's IPv4 address or 4 first bytes of MD5 hash of IPv6
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*/
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uint32_t refid;
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uint8_t leap;
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uint8_t ntp_status;
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/* precision is defined as the larger of the resolution and time to
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* read the clock, in log2 units. For instance, the precision of a
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* mains-frequency clock incrementing at 60 Hz is 16 ms, even when the
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@ -245,8 +245,6 @@ struct globals {
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#define G_precision_sec (1.0 / (1 << (- G_precision_exp)))
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uint8_t stratum;
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/* Bool. After set to 1, never goes back to 0: */
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//TODO: fix logic:
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// uint8_t time_was_stepped;
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uint8_t adjtimex_was_done;
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uint8_t discipline_state; // doc calls it c.state
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@ -415,12 +413,13 @@ filter_datapoints(peer_t *p, double t)
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*/
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wavg = 0;
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w = 0.5;
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// n-1
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// --- dispersion(i)
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// filter_dispersion = \ -------------
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// / (i+1)
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// --- 2
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// i=0
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/* n-1
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* --- dispersion(i)
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* filter_dispersion = \ -------------
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* / (i+1)
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* --- 2
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* i=0
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*/
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got_newest = 0;
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sum = 0;
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for (i = 0; i < NUM_DATAPOINTS; i++) {
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@ -474,21 +473,22 @@ filter_datapoints(peer_t *p, double t)
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}
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p->filter_offset = wavg;
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// +----- -----+ ^ 1/2
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// | n-1 |
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// | --- |
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// 1 | \ 2 |
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// filter_jitter = --- * | / (avg-offset_j) |
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// n | --- |
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// | j=0 |
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// +----- -----+
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// where n is the number of valid datapoints in the filter (n > 1);
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// if filter_jitter < precision then filter_jitter = precision
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/* +----- -----+ ^ 1/2
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* | n-1 |
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* | --- |
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* | 1 \ 2 |
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* filter_jitter = | --- * / (avg-offset_j) |
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* | n --- |
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* | j=0 |
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* +----- -----+
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* where n is the number of valid datapoints in the filter (n > 1);
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* if filter_jitter < precision then filter_jitter = precision
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*/
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sum = 0;
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for (i = 0; i < NUM_DATAPOINTS; i++) {
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sum += SQUARE(wavg - p->filter_datapoint[i].d_offset);
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}
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sum = SQRT(sum) / NUM_DATAPOINTS;
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sum = SQRT(sum / NUM_DATAPOINTS);
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p->filter_jitter = sum > G_precision_sec ? sum : G_precision_sec;
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VERB3 bb_error_msg("filter offset:%f(corr:%e) disp:%f jitter:%f",
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@ -570,22 +570,23 @@ do_sendto(int fd,
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static int
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send_query_to_peer(peer_t *p)
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{
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// Why do we need to bind()?
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// See what happens when we don't bind:
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//
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// socket(PF_INET, SOCK_DGRAM, IPPROTO_IP) = 3
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// setsockopt(3, SOL_IP, IP_TOS, [16], 4) = 0
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// gettimeofday({1259071266, 327885}, NULL) = 0
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// sendto(3, "xxx", 48, MSG_DONTWAIT, {sa_family=AF_INET, sin_port=htons(123), sin_addr=inet_addr("10.34.32.125")}, 16) = 48
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// ^^^ we sent it from some source port picked by kernel.
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// time(NULL) = 1259071266
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// write(2, "ntpd: entering poll 15 secs\n", 28) = 28
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// poll([{fd=3, events=POLLIN}], 1, 15000) = 1 ([{fd=3, revents=POLLIN}])
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// recv(3, "yyy", 68, MSG_DONTWAIT) = 48
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// ^^^ this recv will receive packets to any local port!
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//
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// Uncomment this and use strace to see it in action:
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#define PROBE_LOCAL_ADDR // { len_and_sockaddr lsa; lsa.len = LSA_SIZEOF_SA; getsockname(p->query.fd, &lsa.u.sa, &lsa.len); }
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/* Why do we need to bind()?
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* See what happens when we don't bind:
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*
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* socket(PF_INET, SOCK_DGRAM, IPPROTO_IP) = 3
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* setsockopt(3, SOL_IP, IP_TOS, [16], 4) = 0
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* gettimeofday({1259071266, 327885}, NULL) = 0
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* sendto(3, "xxx", 48, MSG_DONTWAIT, {sa_family=AF_INET, sin_port=htons(123), sin_addr=inet_addr("10.34.32.125")}, 16) = 48
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* ^^^ we sent it from some source port picked by kernel.
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* time(NULL) = 1259071266
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* write(2, "ntpd: entering poll 15 secs\n", 28) = 28
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* poll([{fd=3, events=POLLIN}], 1, 15000) = 1 ([{fd=3, revents=POLLIN}])
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* recv(3, "yyy", 68, MSG_DONTWAIT) = 48
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* ^^^ this recv will receive packets to any local port!
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*
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* Uncomment this and use strace to see it in action:
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*/
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#define PROBE_LOCAL_ADDR /* { len_and_sockaddr lsa; lsa.len = LSA_SIZEOF_SA; getsockname(p->query.fd, &lsa.u.sa, &lsa.len); } */
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if (p->p_fd == -1) {
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int fd, family;
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@ -662,8 +663,6 @@ step_time(double offset)
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strftime(buf, sizeof(buf), "%a %b %e %H:%M:%S %Z %Y", localtime(&tval));
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bb_error_msg("setting clock to %s (offset %fs)", buf, offset);
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// G.time_was_stepped = 1;
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}
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@ -705,13 +704,14 @@ fit(peer_t *p, double rd)
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VERB3 bb_error_msg("peer %s unfit for selection: unreachable", p->p_dotted);
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return 0;
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}
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//TODO: we never accept such packets anyway, right?
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if ((p->lastpkt_leap & LI_ALARM) == LI_ALARM
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#if 0 /* we filter out such packets earlier */
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if ((p->lastpkt_status & LI_ALARM) == LI_ALARM
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|| p->lastpkt_stratum >= MAXSTRAT
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) {
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VERB3 bb_error_msg("peer %s unfit for selection: bad status/stratum", p->p_dotted);
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return 0;
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}
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#endif
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/* rd is root_distance(p, t) */
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if (rd > MAXDIST + FREQ_TOLERANCE * (1 << G.poll_exp)) {
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VERB3 bb_error_msg("peer %s unfit for selection: root distance too high", p->p_dotted);
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@ -908,7 +908,6 @@ select_and_cluster(double t)
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selection_jitter_sq = 0;
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for (j = 0; j < num_survivors; j++) {
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peer_t *q = survivor[j].p;
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//TODO: where is 1/(n-1) * ... multiplier?
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selection_jitter_sq += SQUARE(p->filter_offset - q->filter_offset);
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}
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if (i == 0 || selection_jitter_sq > max_selection_jitter) {
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@ -918,7 +917,7 @@ select_and_cluster(double t)
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VERB5 bb_error_msg("survivor %d selection_jitter^2:%f",
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i, selection_jitter_sq);
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}
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max_selection_jitter = SQRT(max_selection_jitter);
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max_selection_jitter = SQRT(max_selection_jitter / num_survivors);
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VERB4 bb_error_msg("max_selection_jitter (at %d):%f min_jitter:%f",
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max_idx, max_selection_jitter, min_jitter);
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@ -991,7 +990,9 @@ update_local_clock(peer_t *p, double t)
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double offset = p->filter_offset;
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double recv_time = p->lastpkt_recv_time;
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double abs_offset;
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#if !USING_KERNEL_PLL_LOOP
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double freq_drift;
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#endif
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double since_last_update;
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double etemp, dtemp;
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@ -1017,7 +1018,9 @@ update_local_clock(peer_t *p, double t)
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* and frequency errors.
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*/
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since_last_update = recv_time - G.reftime;
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#if !USING_KERNEL_PLL_LOOP
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freq_drift = 0;
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#endif
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if (G.discipline_state == STATE_FREQ) {
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/* Ignore updates until the stepout threshold */
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if (since_last_update < WATCH_THRESHOLD) {
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@ -1025,7 +1028,9 @@ update_local_clock(peer_t *p, double t)
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WATCH_THRESHOLD - since_last_update);
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return 0; /* "leave poll interval as is" */
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}
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#if !USING_KERNEL_PLL_LOOP
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freq_drift = (offset - G.last_update_offset) / since_last_update;
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#endif
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}
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/* There are two main regimes: when the
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@ -1145,6 +1150,7 @@ update_local_clock(peer_t *p, double t)
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break;
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default:
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#if !USING_KERNEL_PLL_LOOP
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/* Compute freq_drift due to PLL and FLL contributions.
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*
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* The FLL and PLL frequency gain constants
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@ -1167,6 +1173,7 @@ update_local_clock(peer_t *p, double t)
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etemp = MIND(since_last_update, (1 << G.poll_exp));
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dtemp = (4 * PLL) << G.poll_exp;
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freq_drift += offset * etemp / SQUARE(dtemp);
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#endif
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set_new_values(STATE_SYNC, offset, recv_time);
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break;
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}
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@ -1174,7 +1181,7 @@ update_local_clock(peer_t *p, double t)
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}
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G.reftime = t;
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G.leap = p->lastpkt_leap;
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G.ntp_status = p->lastpkt_status;
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G.refid = p->lastpkt_refid;
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G.rootdelay = p->lastpkt_rootdelay + p->lastpkt_delay;
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dtemp = p->filter_jitter; // SQRT(SQUARE(p->filter_jitter) + SQUARE(s.jitter));
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@ -1241,10 +1248,10 @@ update_local_clock(peer_t *p, double t)
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/* + (G.last_update_offset < 0 ? -0.5 : 0.5) - too small to bother */
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+ old_tmx_offset; /* almost always 0 */
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tmx.status = STA_PLL;
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//if (sys_leap == LEAP_ADDSECOND)
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// tmx.status |= STA_INS;
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//else if (sys_leap == LEAP_DELSECOND)
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// tmx.status |= STA_DEL;
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if (G.ntp_status & LI_PLUSSEC)
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tmx.status |= STA_INS;
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if (G.ntp_status & LI_MINUSSEC)
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tmx.status |= STA_DEL;
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tmx.constant = G.poll_exp - 4;
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//tmx.esterror = (u_int32)(clock_jitter * 1e6);
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//tmx.maxerror = (u_int32)((sys_rootdelay / 2 + sys_rootdisp) * 1e6);
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@ -1376,18 +1383,12 @@ recv_and_process_peer_pkt(peer_t *p)
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goto close_sock;
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}
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// /*
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// * Verify the server is synchronized with valid stratum and
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// * reference time not later than the transmit time.
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// */
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// if (p->lastpkt_leap == NOSYNC || p->lastpkt_stratum >= MAXSTRAT)
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// return; /* unsynchronized */
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//
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// /* Verify valid root distance */
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// if (msg.m_rootdelay / 2 + msg.m_rootdisp >= MAXDISP || p->lastpkt_reftime > msg.m_xmt)
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// return; /* invalid header values */
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p->lastpkt_leap = msg.m_status;
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p->lastpkt_status = msg.m_status;
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p->lastpkt_stratum = msg.m_stratum;
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p->lastpkt_rootdelay = sfp_to_d(msg.m_rootdelay);
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p->lastpkt_rootdisp = sfp_to_d(msg.m_rootdisp);
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p->lastpkt_refid = msg.m_refid;
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@ -1557,7 +1558,7 @@ recv_and_process_client_pkt(void /*int fd*/)
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/* Build a reply packet */
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memset(&msg, 0, sizeof(msg));
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msg.m_status = G.stratum < MAXSTRAT ? G.leap : LI_ALARM;
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msg.m_status = G.stratum < MAXSTRAT ? G.ntp_status : LI_ALARM;
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msg.m_status |= (query_status & VERSION_MASK);
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msg.m_status |= ((query_status & MODE_MASK) == MODE_CLIENT) ?
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MODE_SERVER : MODE_SYM_PAS;
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@ -1822,10 +1823,6 @@ int ntpd_main(int argc UNUSED_PARAM, char **argv)
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}
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}
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// if ((trial_cnt > 0 && sent_cnt == 0) || g.peer_cnt == 0) {
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// G.time_was_stepped = 1;
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// }
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timeout = nextaction - cur_time;
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if (timeout < 1)
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timeout = 1;
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