Experimental Physics and
Industrial Control System

Hi Mike,

On 05/17/2016 11:05 AM, Michael Westfall wrote:
> Is there a way to delay initializing the NTP time provider until after
> my custom clock tick provider has set the system clock tick rate?

There was a change committed to the 3.15 branch of Base before 3.15.1 to
make the NTP time provider adjust automatically to changes in the system
clock tick rate. Changing the tick rate after iocInit is not advisable,
but in your case this change may be all you need. Since you're evidently
using a 3.14.12 release of Base you should be able to apply the attached
patch file to your copy.

HTH,

- Andrew

-- 
Arguing for surveillance because you have nothing to hide is no
different than making the claim, "I don't care about freedom of
speech because I have nothing to say." -- Edward Snowdon

=== modified file 'documentation/RELEASE_NOTES.html'
--- documentation/RELEASE_NOTES.html	2014-02-13 15:59:10 +0000
+++ documentation/RELEASE_NOTES.html	2014-02-13 16:09:12 +0000
@@ -15,6 +15,14 @@
 <h2 align="center">Changes between 3.15.0.1 and 3.15.0.2</h2>
 <!-- Insert new items immediately below here ... -->
 
+<h3>NTP Time Provider adjusts to OS tick rate changes</h3>
+
+<p>Dirk Zimoch provided code that allows the NTP Time provider (used on VxWorks
+and RTEMS only) to adapt to changes in the OS clock tick rate after the provider
+has been initialized. Note that changing the tick rate after iocInit() is not
+advisable, and that other software might still misbehave if initialized before
+an OS tick rate change.</p>
+
 <h3>Added newEpicsMutex macro</h3>
 
 <p>Internal C++ uses of <tt>new epicsMutex()</tt> have been replaced with a new

=== modified file 'src/libCom/osi/osiNTPTime.c'
--- src/libCom/osi/osiNTPTime.c	2010-10-22 22:34:13 +0000
+++ src/libCom/osi/osiNTPTime.c	2014-02-13 16:09:12 +0000
@@ -47,8 +47,6 @@
     epicsUInt32     syncTick;
     epicsTimeStamp  clockTime;
     epicsUInt32     clockTick;
-    epicsUInt32     nsecsPerTick;
-    epicsUInt32     ticksPerSecond;
     epicsUInt32     ticksToSkip;
     double          tickRate;
 } NTPTimePvt;
@@ -90,8 +88,6 @@
     NTPTimePvt.loopEvent      = epicsEventMustCreate(epicsEventEmpty);
     NTPTimePvt.syncsFailed    = 0;
     NTPTimePvt.lock           = epicsMutexCreate();
-    NTPTimePvt.ticksPerSecond = osdTickRateGet();
-    NTPTimePvt.nsecsPerTick   = NSEC_PER_SEC / NTPTimePvt.ticksPerSecond;
 
     /* Initialize OS-dependent code */
     osdNTPInit();
@@ -100,7 +96,7 @@
     if (!osdNTPGet(&timespecNow)) {
         NTPTimePvt.syncTick = osdTickGet();
         if (timespecNow.tv_sec > POSIX_TIME_AT_EPICS_EPOCH && epicsTimeOK ==
-            epicsTimeFromTimespec(&NTPTimePvt.syncTime, &timespecNow)) {
+                epicsTimeFromTimespec(&NTPTimePvt.syncTime, &timespecNow)) {
             NTPTimePvt.clockTick = NTPTimePvt.syncTick;
             NTPTimePvt.clockTime = NTPTimePvt.syncTime;
             NTPTimePvt.synchronized = 1;
@@ -191,7 +187,7 @@
         if (diff >= 0.0) {
             NTPTimePvt.ticksToSkip = 0;
         } else { /* dont go back in time */
-            NTPTimePvt.ticksToSkip = -diff * NTPTimePvt.ticksPerSecond;
+            NTPTimePvt.ticksToSkip = -diff * osdTickRateGet();
         }
         NTPTimePvt.clockTick = tickNow;
         NTPTimePvt.clockTime = timeNow;
@@ -230,10 +226,12 @@
         }
 
         if (ticksSince) {
-            epicsUInt32 secsSince = ticksSince / NTPTimePvt.ticksPerSecond;
-            ticksSince -= secsSince * NTPTimePvt.ticksPerSecond;
+            epicsUInt32 ticksPerSecond = osdTickRateGet();
+            epicsUInt32 nsecsPerTick = NSEC_PER_SEC / ticksPerSecond;
+            epicsUInt32 secsSince = ticksSince / ticksPerSecond;
 
-            NTPTimePvt.clockTime.nsec += ticksSince * NTPTimePvt.nsecsPerTick;
+            ticksSince -= secsSince * ticksPerSecond;
+            NTPTimePvt.clockTime.nsec += ticksSince * nsecsPerTick;
             if (NTPTimePvt.clockTime.nsec >= NSEC_PER_SEC) {
                 secsSince++;
                 NTPTimePvt.clockTime.nsec -= NSEC_PER_SEC;
@@ -265,14 +263,15 @@
         }
         if (level) {
             char lastSync[32];
+
             epicsTimeToStrftime(lastSync, sizeof(lastSync),
                 "%Y-%m-%d %H:%M:%S.%06f", &NTPTimePvt.syncTime);
             printf("Syncronization interval = %.1f seconds\n",
                 NTPTimeSyncInterval);
             printf("Last synchronized at %s\n",
                 lastSync);
-            printf("OS tick rate = %u Hz (nominal)\n",
-                NTPTimePvt.ticksPerSecond);
+            printf("Current OS tick rate = %u Hz\n",
+                osdTickRateGet());
             printf("Measured tick rate = %.3f Hz\n",
                 NTPTimePvt.tickRate);
             osdNTPReport();

Replies:

Re: NTP time provider and ticksPerSecond Michael Westfall

Re: NTP time provider and ticksPerSecond Matt Rippa

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NTP time provider and ticksPerSecond Michael Westfall

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