clientlog: undo clock adjustments in updated TX timestamps
When the server clock was updated between saving of the RX timestamp and updating the TX timestamp, a client using interleaved mode with the four timestamps which minimize error in measured delay (e.g. chrony) had the server clock adjustment included in the measured delay, which could disrupt the sample filtering and weighting. Add a handler to track the slew epoch and remember the last offset. Undo the adjustment in TX timestamps which have their RX timestamp in the previous epoch to fix the delay observed by the clients. If an unknown clock step is detected, drop all timestamps.
This commit is contained in:
Miroslav Lichvar
parent
189bf9c536
commit
bc33e1cda1
4 changed files with 94 additions and 6 deletions
50
clientlog.c
50
clientlog.c
|
|
@ -38,6 +38,7 @@
|
|||
#include "array.h"
|
||||
#include "clientlog.h"
|
||||
#include "conf.h"
|
||||
#include "local.h"
|
||||
#include "memory.h"
|
||||
#include "ntp.h"
|
||||
#include "reports.h"
|
||||
|
|
@ -125,7 +126,8 @@ static int active;
|
|||
/* RX and TX timestamp saved for clients using interleaved mode */
|
||||
typedef struct {
|
||||
uint64_t rx_ts;
|
||||
uint32_t flags;
|
||||
uint16_t flags;
|
||||
uint16_t slew_epoch;
|
||||
int32_t tx_ts_offset;
|
||||
} NtpTimestamps;
|
||||
|
||||
|
|
@ -141,6 +143,8 @@ typedef struct {
|
|||
uint32_t max_size;
|
||||
uint32_t cached_index;
|
||||
uint64_t cached_rx_ts;
|
||||
uint16_t slew_epoch;
|
||||
double slew_offset;
|
||||
} NtpTimestampMap;
|
||||
|
||||
static NtpTimestampMap ntp_ts_map;
|
||||
|
|
@ -163,6 +167,8 @@ static uint32_t total_record_drops;
|
|||
/* ================================================== */
|
||||
|
||||
static int expand_hashtable(void);
|
||||
static void handle_slew(struct timespec *raw, struct timespec *cooked, double dfreq,
|
||||
double doffset, LCL_ChangeType change_type, void *anything);
|
||||
|
||||
/* ================================================== */
|
||||
|
||||
|
|
@ -407,6 +413,10 @@ CLG_Initialise(void)
|
|||
ntp_ts_map.max_size = 1U << (slots2 + SLOT_BITS);
|
||||
ntp_ts_map.cached_index = 0;
|
||||
ntp_ts_map.cached_rx_ts = 0ULL;
|
||||
ntp_ts_map.slew_epoch = 0;
|
||||
ntp_ts_map.slew_offset = 0.0;
|
||||
|
||||
LCL_AddParameterChangeHandler(handle_slew, NULL);
|
||||
}
|
||||
|
||||
/* ================================================== */
|
||||
|
|
@ -420,6 +430,8 @@ CLG_Finalise(void)
|
|||
ARR_DestroyInstance(records);
|
||||
if (ntp_ts_map.timestamps)
|
||||
ARR_DestroyInstance(ntp_ts_map.timestamps);
|
||||
|
||||
LCL_RemoveParameterChangeHandler(handle_slew, NULL);
|
||||
}
|
||||
|
||||
/* ================================================== */
|
||||
|
|
@ -864,6 +876,7 @@ CLG_SaveNtpTimestamps(NTP_int64 *rx_ts, struct timespec *tx_ts)
|
|||
tss = get_ntp_tss(index);
|
||||
tss->rx_ts = rx;
|
||||
tss->flags = 0;
|
||||
tss->slew_epoch = ntp_ts_map.slew_epoch;
|
||||
set_ntp_tx_offset(tss, rx_ts, tx_ts);
|
||||
|
||||
DEBUG_LOG("Saved RX+TX index=%"PRIu32" first=%"PRIu32" size=%"PRIu32,
|
||||
|
|
@ -872,6 +885,41 @@ CLG_SaveNtpTimestamps(NTP_int64 *rx_ts, struct timespec *tx_ts)
|
|||
|
||||
/* ================================================== */
|
||||
|
||||
static void
|
||||
handle_slew(struct timespec *raw, struct timespec *cooked, double dfreq,
|
||||
double doffset, LCL_ChangeType change_type, void *anything)
|
||||
{
|
||||
/* Drop all timestamps on unknown step */
|
||||
if (change_type == LCL_ChangeUnknownStep) {
|
||||
ntp_ts_map.size = 0;
|
||||
ntp_ts_map.cached_rx_ts = 0ULL;
|
||||
}
|
||||
|
||||
ntp_ts_map.slew_epoch++;
|
||||
ntp_ts_map.slew_offset = doffset;
|
||||
}
|
||||
|
||||
/* ================================================== */
|
||||
|
||||
void
|
||||
CLG_UndoNtpTxTimestampSlew(NTP_int64 *rx_ts, struct timespec *tx_ts)
|
||||
{
|
||||
uint32_t index;
|
||||
|
||||
if (!ntp_ts_map.timestamps)
|
||||
return;
|
||||
|
||||
if (!find_ntp_rx_ts(ntp64_to_int64(rx_ts), &index))
|
||||
return;
|
||||
|
||||
/* If the RX timestamp was captured before the last correction of the clock,
|
||||
remove the adjustment from the TX timestamp */
|
||||
if ((uint16_t)(get_ntp_tss(index)->slew_epoch + 1U) == ntp_ts_map.slew_epoch)
|
||||
UTI_AddDoubleToTimespec(tx_ts, ntp_ts_map.slew_offset, tx_ts);
|
||||
}
|
||||
|
||||
/* ================================================== */
|
||||
|
||||
void
|
||||
CLG_UpdateNtpTxTimestamp(NTP_int64 *rx_ts, struct timespec *tx_ts)
|
||||
{
|
||||
|
|
|
|||
|
|
@ -47,6 +47,7 @@ extern int CLG_GetNtpMinPoll(void);
|
|||
|
||||
/* Functions to save and retrieve timestamps for server interleaved mode */
|
||||
extern void CLG_SaveNtpTimestamps(NTP_int64 *rx_ts, struct timespec *tx_ts);
|
||||
extern void CLG_UndoNtpTxTimestampSlew(NTP_int64 *rx_ts, struct timespec *tx_ts);
|
||||
extern void CLG_UpdateNtpTxTimestamp(NTP_int64 *rx_ts, struct timespec *tx_ts);
|
||||
extern int CLG_GetNtpTxTimestamp(NTP_int64 *rx_ts, struct timespec *tx_ts);
|
||||
extern void CLG_DisableNtpTimestamps(NTP_int64 *rx_ts);
|
||||
|
|
|
|||
13
ntp_core.c
13
ntp_core.c
|
|
@ -2215,7 +2215,7 @@ void
|
|||
NCR_ProcessTxUnknown(NTP_Remote_Address *remote_addr, NTP_Local_Address *local_addr,
|
||||
NTP_Local_Timestamp *tx_ts, NTP_Packet *message, int length)
|
||||
{
|
||||
NTP_Local_Timestamp local_tx;
|
||||
NTP_Local_Timestamp old_tx, new_tx;
|
||||
NTP_int64 *local_ntp_rx;
|
||||
NTP_PacketInfo info;
|
||||
|
||||
|
|
@ -2229,13 +2229,18 @@ NCR_ProcessTxUnknown(NTP_Remote_Address *remote_addr, NTP_Local_Address *local_a
|
|||
UTI_AddDoubleToTimespec(&tx_ts->ts, SMT_GetOffset(&tx_ts->ts), &tx_ts->ts);
|
||||
|
||||
local_ntp_rx = &message->receive_ts;
|
||||
new_tx = *tx_ts;
|
||||
|
||||
if (!CLG_GetNtpTxTimestamp(local_ntp_rx, &local_tx.ts))
|
||||
if (!CLG_GetNtpTxTimestamp(local_ntp_rx, &old_tx.ts))
|
||||
return;
|
||||
|
||||
update_tx_timestamp(&local_tx, tx_ts, local_ntp_rx, NULL, message);
|
||||
/* Undo a clock adjustment between the RX and TX timestamps to minimise error
|
||||
in the delay measured by the client */
|
||||
CLG_UndoNtpTxTimestampSlew(local_ntp_rx, &new_tx.ts);
|
||||
|
||||
CLG_UpdateNtpTxTimestamp(local_ntp_rx, &local_tx.ts);
|
||||
update_tx_timestamp(&old_tx, &new_tx, local_ntp_rx, NULL, message);
|
||||
|
||||
CLG_UpdateNtpTxTimestamp(local_ntp_rx, &new_tx.ts);
|
||||
}
|
||||
|
||||
/* ================================================== */
|
||||
|
|
|
|||
|
|
@ -52,6 +52,7 @@ test_unit(void)
|
|||
for (i = 0; i < sizeof conf / sizeof conf[0]; i++)
|
||||
CNF_ParseLine(NULL, i + 1, conf[i]);
|
||||
|
||||
LCL_Initialise();
|
||||
CLG_Initialise();
|
||||
|
||||
TEST_CHECK(ARR_GetSize(records) == 16);
|
||||
|
|
@ -115,6 +116,7 @@ test_unit(void)
|
|||
ntp_ts_map.first = i % ntp_ts_map.max_size;
|
||||
ntp_ts_map.size = 0;
|
||||
ntp_ts_map.cached_rx_ts = 0ULL;
|
||||
ntp_ts_map.slew_epoch = i * 400;
|
||||
|
||||
for (j = 0; j < 500; j++) {
|
||||
do {
|
||||
|
|
@ -140,21 +142,41 @@ test_unit(void)
|
|||
TEST_CHECK(ntp_ts_map.size == ntp_ts_map.max_size);
|
||||
TEST_CHECK(ntp_ts_map.first == (i + j + ntp_ts_map.size + 1) % ntp_ts_map.max_size);
|
||||
}
|
||||
TEST_CHECK(ntp_ts_map.cached_index == ntp_ts_map.size - 1);
|
||||
TEST_CHECK(get_ntp_tss(ntp_ts_map.size - 1)->slew_epoch == ntp_ts_map.slew_epoch);
|
||||
TEST_CHECK(CLG_GetNtpTxTimestamp(&ntp_ts, &ts2));
|
||||
TEST_CHECK(UTI_CompareTimespecs(&ts, &ts2) == 0);
|
||||
|
||||
for (k = random() % 4; k > 0; k--) {
|
||||
int64_to_ntp64(get_ntp_tss(random() % ntp_ts_map.size)->rx_ts, &ntp_ts);
|
||||
index2 = random() % ntp_ts_map.size;
|
||||
int64_to_ntp64(get_ntp_tss(index2)->rx_ts, &ntp_ts);
|
||||
if (random() % 2)
|
||||
TEST_CHECK(CLG_GetNtpTxTimestamp(&ntp_ts, &ts));
|
||||
|
||||
UTI_Ntp64ToTimespec(&ntp_ts, &ts);
|
||||
UTI_AddDoubleToTimespec(&ts, TST_GetRandomDouble(-1.999, 1.999), &ts);
|
||||
|
||||
ts2 = ts;
|
||||
CLG_UndoNtpTxTimestampSlew(&ntp_ts, &ts);
|
||||
if ((get_ntp_tss(index2)->slew_epoch + 1) % (1U << 16) != ntp_ts_map.slew_epoch) {
|
||||
TEST_CHECK(UTI_CompareTimespecs(&ts, &ts2) == 0);
|
||||
} else {
|
||||
TEST_CHECK(fabs(UTI_DiffTimespecsToDouble(&ts, &ts2) - ntp_ts_map.slew_offset) <
|
||||
1.0e-9);
|
||||
}
|
||||
|
||||
CLG_UpdateNtpTxTimestamp(&ntp_ts, &ts);
|
||||
|
||||
TEST_CHECK(CLG_GetNtpTxTimestamp(&ntp_ts, &ts2));
|
||||
TEST_CHECK(UTI_CompareTimespecs(&ts, &ts2) == 0);
|
||||
|
||||
if (random() % 2) {
|
||||
uint16_t prev_epoch = ntp_ts_map.slew_epoch;
|
||||
handle_slew(NULL, NULL, 0.0, TST_GetRandomDouble(-1.0e-5, 1.0e-5),
|
||||
LCL_ChangeAdjust, NULL);
|
||||
TEST_CHECK((prev_epoch + 1) % (1U << 16) == ntp_ts_map.slew_epoch);
|
||||
}
|
||||
|
||||
if (ntp_ts_map.size > 1) {
|
||||
index = random() % (ntp_ts_map.size - 1);
|
||||
if (get_ntp_tss(index)->rx_ts + 1 != get_ntp_tss(index + 1)->rx_ts) {
|
||||
|
|
@ -163,6 +185,7 @@ test_unit(void)
|
|||
int64_to_ntp64(get_ntp_tss(index + 1)->rx_ts - 1, &ntp_ts);
|
||||
TEST_CHECK(!CLG_GetNtpTxTimestamp(&ntp_ts, &ts));
|
||||
CLG_UpdateNtpTxTimestamp(&ntp_ts, &ts);
|
||||
CLG_UndoNtpTxTimestampSlew(&ntp_ts, &ts);
|
||||
}
|
||||
}
|
||||
|
||||
|
|
@ -172,6 +195,7 @@ test_unit(void)
|
|||
int64_to_ntp64(get_ntp_tss(ntp_ts_map.size - 1)->rx_ts + 1, &ntp_ts);
|
||||
TEST_CHECK(!CLG_GetNtpTxTimestamp(&ntp_ts, &ts));
|
||||
CLG_UpdateNtpTxTimestamp(&ntp_ts, &ts);
|
||||
CLG_UndoNtpTxTimestampSlew(&ntp_ts, &ts);
|
||||
}
|
||||
}
|
||||
}
|
||||
|
|
@ -244,9 +268,19 @@ test_unit(void)
|
|||
CLG_GetNtpTxTimestamp(&ntp_ts, &ts);
|
||||
}
|
||||
}
|
||||
|
||||
if (random() % 2) {
|
||||
handle_slew(NULL, NULL, 0.0, TST_GetRandomDouble(-1.0e9, 1.0e9),
|
||||
LCL_ChangeUnknownStep, NULL);
|
||||
TEST_CHECK(ntp_ts_map.size == 0);
|
||||
TEST_CHECK(ntp_ts_map.cached_rx_ts == 0ULL);
|
||||
TEST_CHECK(!CLG_GetNtpTxTimestamp(&ntp_ts, &ts));
|
||||
CLG_UpdateNtpTxTimestamp(&ntp_ts, &ts);
|
||||
}
|
||||
}
|
||||
|
||||
CLG_Finalise();
|
||||
LCL_Finalise();
|
||||
CNF_Finalise();
|
||||
}
|
||||
#else
|
||||
|
|
|
|||
Loading…
Reference in a new issue