| Re: [chrony-dev] Running chronyd without syncing system clock |
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Op 24/02/2012 om 11:43:01 +0100, schreef Miroslav Lichvar:
> On Fri, Feb 24, 2012 at 11:02:55AM +0100, Leo Baltus wrote:
> > I am not saying that multiple processes should serve a single clock.
> >
> > Let me try some good old ascii art:
> >
> > uplink local nets
> > pool --- ntp-only-server1 --- ntp-client
> > ntp-only-server2 --- ntp-client
> > ntp-only-server3 --- ntp-client
> > --- ntp-client
> >
> > The pool is a set of ntp-servers outside my network. Inside my network I
> > have 4 servers (hardware) each running an ntp-client synchronizing to 3
> > ntp-only-servers (chronyd instances). The ntp-only servers run on the
> > same hardware as the ntp-clients but do not sync the system clock. Each
> > ntp-only server has its own ip address unrelated to the server's ip
> > address. Some hardware is running ntp-clients only. The ntp-clients do
> > sync the system clock. Some ntp clients may even be outside my networks.
>
> Ok, there are two chronyd instances running on one real hw machine,
> one polls remote NTP servers, but doesn't set the clock. The other
> instance polls the first chronyd and sets the local clock. Is that
> correct?
>
All ntp-clients share the same configuration:
server ntp-only-server1
server ntp-only-server2
server ntp-only-server3
> I think that will create a positive feedback loop and will not work
> well, if at all. The instance which sets the clock needs to compare
> its clock against a stable clock, not something which includes its
> own clock.
Wouldn't the one running on its own clock mark it as 'bad' in
comparison with the others?
> It could work the other way around, the client polling remote
> servers and the server polling the client, but that's probably not
> what you want.
>
Right.
> > In the mean time I have prepared a patch to see if i can get this
> > working. Any thoughts about testing scenarios?
>
> I'm interested to see what the patch does.
>
---
conf.c | 21 +++++++++++++++++++++
conf.h | 1 +
reference.c | 14 +++++++++-----
3 files changed, 31 insertions(+), 5 deletions(-)
diff --git a/conf.c b/conf.c
index bbd890c..7da1123 100644
--- a/conf.c
+++ b/conf.c
@@ -94,6 +94,7 @@ static void parse_cmddeny(const char *);
static void parse_cmdport(const char *);
static void parse_rtconutc(const char *);
static void parse_rtcsync(const char *);
+static void parse_nolclsync(const char *);
static void parse_noclientlog(const char *);
static void parse_clientloglimit(const char *);
static void parse_fallbackdrift(const char *);
@@ -165,6 +166,9 @@ static int rtc_on_utc = 0;
/* Flag set if the RTC should be automatically synchronised by kernel */
static int rtc_sync = 0;
+/* Flag set if the local system clock should be synchronised by chrony */
+static int lcl_sync = 1;
+
/* Limit and threshold for clock stepping */
static int make_step_limit = 0;
static double make_step_threshold = 0.0;
@@ -260,6 +264,7 @@ static const Command commands[] = {
{"cmdport", 7, parse_cmdport},
{"rtconutc", 8, parse_rtconutc},
{"rtcsync", 7, parse_rtcsync},
+ {"nolclsync", 7, parse_nolclsync},
{"noclientlog", 11, parse_noclientlog},
{"clientloglimit", 14, parse_clientloglimit},
{"fallbackdrift", 13, parse_fallbackdrift},
@@ -906,6 +911,14 @@ parse_rtcsync(const char *line)
/* ================================================== */
static void
+parse_nolclsync(const char *line)
+{
+ lcl_sync = 0;
+}
+
+/* ================================================== */
+
+static void
parse_noclientlog(const char *line)
{
no_client_log = 1;
@@ -1579,6 +1592,14 @@ CNF_GetRTCSync(void)
/* ================================================== */
+int
+CNF_GetLCLSync(void)
+{
+ return lcl_sync;
+}
+
+/* ================================================== */
+
void
CNF_GetMakeStep(int *limit, double *threshold)
{
diff --git a/conf.h b/conf.h
index 7f0f6b3..1fdc616 100644
--- a/conf.h
+++ b/conf.h
@@ -59,6 +59,7 @@ extern int CNF_GetManualEnabled(void);
extern int CNF_GetCommandPort(void);
extern int CNF_GetRTCOnUTC(void);
extern int CNF_GetRTCSync(void);
+extern int CNF_GetLCLSync(void);
extern void CNF_GetMakeStep(int *limit, double *threshold);
extern void CNF_GetMaxChange(int *delay, int *ignore, double *offset);
extern void CNF_GetLogChange(int *enabled, double *threshold);
diff --git a/reference.c b/reference.c
index 7bf8ec7..7c8f414 100644
--- a/reference.c
+++ b/reference.c
@@ -494,7 +494,7 @@ maybe_make_step()
} else if (make_step_limit > 0) {
make_step_limit--;
}
- LCL_MakeStep(make_step_threshold);
+ if (CNF_GetLCLSync()) LCL_MakeStep(make_step_threshold);
}
/* ================================================== */
@@ -705,16 +705,20 @@ REF_SetReference(int stratum,
our_residual_freq = new_freq - our_frequency;
- maybe_log_offset(our_offset);
- LCL_AccumulateFrequencyAndOffset(our_frequency, our_offset, correction_rate);
+ if (CNF_GetLCLSync()) {
+ maybe_log_offset(our_offset);
+ LCL_AccumulateFrequencyAndOffset(our_frequency, our_offset, correction_rate);
+ }
} else {
#if 0
LOG(LOGS_INFO, LOGF_Reference, "Skew %f too large to track, offset=%f", skew, our_offset);
#endif
- maybe_log_offset(our_offset);
- LCL_AccumulateOffset(our_offset, correction_rate);
+ if (CNF_GetLCLSync()) {
+ maybe_log_offset(our_offset);
+ LCL_AccumulateOffset(our_offset, correction_rate);
+ }
our_residual_freq = frequency;
}
--
1.7.4.4
--
Leo Baltus, internetbeheerder /\
NPO ICT Internet Services /NPO/\
Sumatralaan 45, 1217 GP Hilversum, Filmcentrum, west \ /\/
beheer@xxxxxxxxx, 035-6773555 \/
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