Thanks Richard for the feedback. Please find update comments with code changes.
>From a8e9b8ade110ff9eb9acc2bb28c6e3d1db136c29 Mon Sep 17 00:00:00 2001
From: Ramesh Gowda <ramesh.go...@mavenir.com>
Date: Thu, 12 Oct 2023 15:26:27 +0530
Subject: [PATCH] GNSS fluctuation resulting in wrong update of NIC PHC time.
Context:
Under GNSS fluctuation condition due bad weather or improper location of GNSS
antenna, observed ts2phc process updates 1 sec difference into the physical
hard clock (PHC) of the NIC.
This 1 sec jump is seen momentarily as captured below.
Mar 10 15:17:40 sno-cluster-nrnl04-master1 ts2phc: [161756.611] nmea delay:
89943030 ns
Mar 10 15:17:40 sno-cluster-nrnl04-master1 ts2phc: [161756.611] enp81s0f0
extts index 0 at 1678461497.000000000 corr 0 src 1678461498.844774711 diff
-1000000000
Mar 10 15:17:40 sno-cluster-nrnl04-master1 ts2phc: [161756.611] enp81s0f0
master offset -1000000000 s2 freq -100000000
Mar 10 15:17:40 sno-cluster-nrnl04-master1 ts2phc: [161756.612] nmea delay:
89943030 ns
Mar 10 15:17:40 sno-cluster-nrnl04-master1 ts2phc: [161756.612] enp138s0f0
extts index 0 at 1678461497.000000000 corr 0 src 1678461498.845574965 diff
-1000000000
Mar 10 15:17:40 sno-cluster-nrnl04-master1 ts2phc: [161756.612] enp138s0f0
master offset -1000000000 s2 freq -100000000
Problem:
ts2phc process will update wrong timing into PHC, this time is periodically
copied into system timing using phc2sys process.
This will result in sudden jump of time in system clock impacting others
processes which are tightly bound to system timing.
Solution:
With ts2phc in SERVO_LOCKED state, time difference between PHC and GPS would be
in +-1ns.
But under problem condition, the time difference will be +-1 sec.
To prevent wrong update of time, defined a new configurable variable called
skip count.
With SERVO_LOCKED state and time diff is more than 500 msecond, ts2phc will
skip update of PHC for configured skip count value.
Default skip count value would be set 120 (2 minutes).
Time difference stays more than 500 msecond for continuous intervals more than
skip count value, ts2phc will update the PHC with time difference value.
---
config.c | 1 +
ts2phc.c | 3 +++
ts2phc_slave.c | 23 +++++++++++++++++++++++
3 files changed, 27 insertions(+)
diff --git a/config.c b/config.c
index d237de9..2a9ee6b 100644
--- a/config.c
+++ b/config.c
@@ -331,6 +331,7 @@ struct config_item config_tab[] = {
GLOB_ITEM_INT("utc_offset", CURRENT_UTC_OFFSET, 0, INT_MAX),
GLOB_ITEM_INT("verbose", 0, 0, 1),
GLOB_ITEM_INT("write_phase_mode", 0, 0, 1),
+ PORT_ITEM_INT("max_phc_update_skip_cnt", 120, 0, 14400),
};
static struct unicast_master_table *current_uc_mtab;
diff --git a/ts2phc.c b/ts2phc.c
index 2342858..5687c9b 100644
--- a/ts2phc.c
+++ b/ts2phc.c
@@ -15,6 +15,8 @@
#include "ts2phc_slave.h"
#include "version.h"
+int max_phc_update_skip_count;
+
struct interface {
STAILQ_ENTRY(interface) list;
};
@@ -146,6 +148,7 @@ int main(int argc, char *argv[])
print_set_verbose(config_get_int(cfg, NULL, "verbose"));
print_set_syslog(config_get_int(cfg, NULL, "use_syslog"));
print_set_level(config_get_int(cfg, NULL, "logging_level"));
+ max_phc_update_skip_count = config_get_int(cfg, NULL,
"max_phc_update_skip_cnt");
STAILQ_FOREACH(iface, &cfg->interfaces, list) {
if (1 == config_get_int(cfg, interface_name(iface), "ts2phc.master")) {
diff --git a/ts2phc_slave.c b/ts2phc_slave.c
index 749efe5..6af1aeb 100644
--- a/ts2phc_slave.c
+++ b/ts2phc_slave.c
@@ -29,6 +29,8 @@
#define SAMPLE_WEIGHT 1.0
#define SERVO_SYNC_INTERVAL 1.0
+extern int max_phc_update_skip_count;
+
struct ts2phc_slave {
char *name;
STAILQ_ENTRY(ts2phc_slave) list;
@@ -42,6 +44,8 @@ struct ts2phc_slave {
clockid_t clk;
int no_adj;
int fd;
+ int max_offset_skip_count;
+ int current_offset_skip_count;
};
struct ts2phc_slave_array {
@@ -219,6 +223,10 @@ static struct ts2phc_slave *ts2phc_slave_create(struct
config *cfg, const char *
goto no_ext_ts;
}
+ slave->max_offset_skip_count = max_phc_update_skip_count;
+ slave->current_offset_skip_count = 0;
+ pr_debug("PHC slave %s has skip cnt %d", device,
slave->max_offset_skip_count);
+
return slave;
no_ext_ts:
no_pin_func:
@@ -278,6 +286,17 @@ static int ts2phc_slave_event(struct ts2phc_slave *slave,
adj = servo_sample(slave->servo, offset, extts_ts,
SAMPLE_WEIGHT, &slave->state);
+ if ((slave->state == SERVO_LOCKED) || (slave->state ==
SERVO_LOCKED_STABLE)) {
+ if (llabs(offset) >= NS_PER_SEC / 2) {
+ if (slave->current_offset_skip_count <
slave->max_offset_skip_count) {
+ pr_debug("Skip current PHC update %s offset %10" PRId64 " s%d
freq %+7.0f",
+ slave->name, offset, slave->state, adj);
+ slave->current_offset_skip_count++;
+ return 0;
+ }
+ }
+ }
+
pr_debug("%s master offset %10" PRId64 " s%d freq %+7.0f",
slave->name, offset, slave->state, adj);
@@ -290,6 +309,10 @@ static int ts2phc_slave_event(struct ts2phc_slave *slave,
break;
case SERVO_LOCKED:
case SERVO_LOCKED_STABLE:
+ if (llabs(offset) < 500) {
+ slave->current_offset_skip_count = 0;
+ }
+
clockadj_set_freq(slave->clk, -adj);
break;
}
--
2.20.1
On Friday, November 10, 2023 at 11:46:05 AM GMT+5:30, Richard Cochran
<richardcoch...@gmail.com> wrote:
On Thu, Nov 09, 2023 at 06:07:57PM +0000, ramesh t via Linuxptp-devel wrote:
> Update Code review request. Can you please provide comments?
You have not identified any problem, and so I cannot comment.
A proper commit message has three elements:
1. context
2. problem
3. solution
That means writing at least three complete, coherent sentences.
Thanks,
Richard
0001-GNSS-fluctuation-resulting-in-wrong-update-of-NIC-PH.patch
Description: Binary data
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