From 6aec8d9bcb4ee7f0c68aed5abddcc034fbbe45f4 Mon Sep 17 00:00:00 2001
From: Michael Davidsaver <mdavidsaver@gmail.com>
Date: Tue, 25 Aug 2015 18:09:35 -0400
Subject: [PATCH 1/7] libCom/osi: fetch monotonic time

---
 src/libCom/osi/Makefile                 |  1 +
 src/libCom/osi/epicsTime.h              | 11 ++++
 src/libCom/osi/os/Darwin/osdMonotonic.c | 32 +++++++++++
 src/libCom/osi/os/Darwin/osdTime.cpp    |  3 +
 src/libCom/osi/os/RTEMS/osdTime.cpp     |  3 +
 src/libCom/osi/os/WIN32/osdMonotonic.c  | 53 +++++++++++++++++
 src/libCom/osi/os/WIN32/osdTime.cpp     |  3 +
 src/libCom/osi/os/iOS/osdMonotonic.c    | 31 ++++++++++
 src/libCom/osi/os/posix/osdMonotonic.c  | 75 +++++++++++++++++++++++++
 src/libCom/osi/os/posix/osdTime.cpp     |  3 +
 src/libCom/osi/os/vxWorks/osdTime.cpp   |  2 +
 src/libCom/test/epicsTimeTest.cpp       | 45 ++++++++++++++-
 12 files changed, 261 insertions(+), 1 deletion(-)
 create mode 100644 src/libCom/osi/os/Darwin/osdMonotonic.c
 create mode 100644 src/libCom/osi/os/WIN32/osdMonotonic.c
 create mode 100644 src/libCom/osi/os/iOS/osdMonotonic.c
 create mode 100644 src/libCom/osi/os/posix/osdMonotonic.c

diff --git a/src/libCom/osi/Makefile b/src/libCom/osi/Makefile
index c06a862ed..ecbf4c23b 100644
--- a/src/libCom/osi/Makefile
+++ b/src/libCom/osi/Makefile
@@ -119,6 +119,7 @@ Com_SRCS += osdMutex.c
 Com_SRCS += osdSpin.c
 Com_SRCS += osdEvent.c
 Com_SRCS += osdTime.cpp
+Com_SRCS += osdMonotonic.c
 Com_SRCS += osdProcess.c
 Com_SRCS += osdNetIntf.c
 Com_SRCS += osdMessageQueue.c
diff --git a/src/libCom/osi/epicsTime.h b/src/libCom/osi/epicsTime.h
index 149f6f2d3..862bc22d2 100644
--- a/src/libCom/osi/epicsTime.h
+++ b/src/libCom/osi/epicsTime.h
@@ -258,6 +258,17 @@ epicsShareFunc void epicsShareAPI epicsTimeShow (
 epicsShareFunc int epicsShareAPI epicsTime_localtime ( const time_t * clock, struct tm * result );
 epicsShareFunc int epicsShareAPI epicsTime_gmtime ( const time_t * clock, struct tm * result );
 
+/* Advertised monotonic counter resolution (may not be accurate).
+ * Minimum non-zero difference between two calls to epicsMonotonicGet()
+ */
+epicsShareFunc epicsUInt64 epicsMonotonicResolution(void);
+/* Fetch monotonic counter, return is nano-seconds since an unspecified time */
+epicsShareFunc epicsUInt64 epicsMonotonicGet(void);
+
+#ifdef EPICS_EXPOSE_LIBCOM_MONOTONIC_PRIVATE
+epicsShareFunc void osdMonotonicInit(void);
+#endif
+
 #ifdef __cplusplus
 }
 #endif /* __cplusplus */
diff --git a/src/libCom/osi/os/Darwin/osdMonotonic.c b/src/libCom/osi/os/Darwin/osdMonotonic.c
new file mode 100644
index 000000000..50ca82ef6
--- /dev/null
+++ b/src/libCom/osi/os/Darwin/osdMonotonic.c
@@ -0,0 +1,32 @@
+/*************************************************************************\
+* Copyright (c) 2015 Michael Davidsaver
+* EPICS BASE is distributed subject to a Software License Agreement found
+* in file LICENSE that is included with this distribution.
+\*************************************************************************/
+
+#include <kern/clock.h>
+#include <mach/mach_time.h>
+
+#define epicsExportSharedSymbols
+#include "dbDefs.h"
+#include "errlog.h"
+#define EPICS_EXPOSE_LIBCOM_MONOTONIC_PRIVATE
+#include "epicsTime.h"
+#include "generalTimeSup.h"
+
+void osdMonotonicInit(void)
+{
+    /* no-op */
+}
+
+epicsUInt64 epicsMonotonicResolution(void)
+{
+    return 1; /* TODO, how to find ? */
+}
+
+epicsUInt64 epicsMonotonicGet(void)
+{
+    uint64_t val = mach_absolute_time(), ret;
+    absolutetime_to_nanoseconds(val, &ret);
+    return ret;
+}
diff --git a/src/libCom/osi/os/Darwin/osdTime.cpp b/src/libCom/osi/os/Darwin/osdTime.cpp
index 72b3dc874..7bddc7da2 100644
--- a/src/libCom/osi/os/Darwin/osdTime.cpp
+++ b/src/libCom/osi/os/Darwin/osdTime.cpp
@@ -19,6 +19,7 @@
 
 #define epicsExportSharedSymbols
 #include "cantProceed.h"
+#define EPICS_EXPOSE_LIBCOM_MONOTONIC_PRIVATE
 #include "epicsTime.h"
 #include "generalTimeSup.h"
 
@@ -45,6 +46,8 @@ static int timeRegister(void)
 
     generalTimeCurrentTpRegister("MachTime", \
         LAST_RESORT_PRIORITY, osdTimeGetCurrent);
+
+    osdMonotonicInit();
     return 1;
 }
 static int done = timeRegister();
diff --git a/src/libCom/osi/os/RTEMS/osdTime.cpp b/src/libCom/osi/os/RTEMS/osdTime.cpp
index 4947c568e..a9d5c2ea6 100644
--- a/src/libCom/osi/os/RTEMS/osdTime.cpp
+++ b/src/libCom/osi/os/RTEMS/osdTime.cpp
@@ -20,6 +20,7 @@
 #include <sys/socket.h>
 #include <netinet/in.h>
 #include <rtems/rtems_bsdnet_internal.h>
+#define EPICS_EXPOSE_LIBCOM_MONOTONIC_PRIVATE
 #include "epicsTime.h"
 #include "osdTime.h"
 #include "osiNTPTime.h"
@@ -37,6 +38,8 @@ void osdTimeRegister(void)
     /* Init NTP first so it can be used to sync ClockTime */
     NTPTime_Init(100);
     ClockTime_Init(CLOCKTIME_SYNC);
+
+    osdMonotonicInit();
 }
 
 int osdNTPGet(struct timespec *ts)
diff --git a/src/libCom/osi/os/WIN32/osdMonotonic.c b/src/libCom/osi/os/WIN32/osdMonotonic.c
new file mode 100644
index 000000000..342ee7d60
--- /dev/null
+++ b/src/libCom/osi/os/WIN32/osdMonotonic.c
@@ -0,0 +1,53 @@
+/*************************************************************************\
+* Copyright (c) 2015 Michael Davidsaver
+* EPICS BASE is distributed subject to a Software License Agreement found
+* in file LICENSE that is included with this distribution.
+\*************************************************************************/
+
+#include <windows.h>
+
+#define epicsExportSharedSymbols
+#include "dbDefs.h"
+#include "errlog.h"
+#define EPICS_EXPOSE_LIBCOM_MONOTONIC_PRIVATE
+#include "epicsTime.h"
+#include "generalTimeSup.h"
+
+static unsigned char osdUsePrefCounter;
+static epicsUInt64 osdMonotonicResolution;
+
+void osdMonotonicInit(void)
+{
+    LARGE_INTEGER freq, val;
+
+    if(!QueryPerformanceFrequency(&freq) ||
+            !QueryPerformanceCounter(&val))
+    {
+        double period = 1.0/freq.QuadPart;
+        osdMonotonicResolution = period*1e9;
+        osdUsePrefCounter = 1;
+    } else {
+        osdMonotonicResolution = 1e6; /* 1 ms TODO place holder */
+    }
+}
+
+epicsUInt64 epicsMonotonicResolution(void)
+{
+    return osdMonotonicResolution;
+}
+
+epicsUInt64 epicsMonotonicGet(void)
+{
+    LARGE_INTEGER val;
+    if(osdUsePrefCounter) {
+        if(!QueryPerformanceCounter(&val)) {
+            errMessage(errlogMinor, "Warning: failed to fetch performance counter\n");
+            return 0;
+        } else
+            return val.QuadPart;
+    } else {
+        epicsUInt64 ret = GetTickCount();
+        ret *= 1000000;
+        return ret;
+    }
+}
diff --git a/src/libCom/osi/os/WIN32/osdTime.cpp b/src/libCom/osi/os/WIN32/osdTime.cpp
index 2ee0d3066..348fe7c2f 100644
--- a/src/libCom/osi/os/WIN32/osdTime.cpp
+++ b/src/libCom/osi/os/WIN32/osdTime.cpp
@@ -31,6 +31,7 @@
 // EPICS
 //
 #define epicsExportSharedSymbols
+#define EPICS_EXPOSE_LIBCOM_MONOTONIC_PRIVATE
 #include "epicsTime.h"
 #include "generalTimeSup.h"
 #include "epicsTimer.h"
@@ -106,6 +107,8 @@ static int timeRegister(void)
     generalTimeCurrentTpRegister("PerfCounter", 150, osdTimeGetCurrent);
 
     pCurrentTime->startPLL ();
+
+    osdMonotonicInit();
     return 1;
 }
 static int done = timeRegister();
diff --git a/src/libCom/osi/os/iOS/osdMonotonic.c b/src/libCom/osi/os/iOS/osdMonotonic.c
new file mode 100644
index 000000000..0c2c7718f
--- /dev/null
+++ b/src/libCom/osi/os/iOS/osdMonotonic.c
@@ -0,0 +1,31 @@
+/*************************************************************************\
+* Copyright (c) 2015 Michael Davidsaver
+* EPICS BASE is distributed subject to a Software License Agreement found
+* in file LICENSE that is included with this distribution.
+\*************************************************************************/
+
+#import <mach/mach_time.h>
+
+#define epicsExportSharedSymbols
+#include "dbDefs.h"
+#include "errlog.h"
+#define EPICS_EXPOSE_LIBCOM_MONOTONIC_PRIVATE
+#include "epicsTime.h"
+#include "generalTimeSup.h"
+
+void osdMonotonicInit(void)
+{
+    /* no-op */
+}
+
+epicsUInt64 epicsMonotonicResolution(void)
+{
+    return 1; /* TODO, how to find ? */
+}
+
+epicsUInt64 epicsMonotonicGet(void)
+{
+    uint64_t val = mach_absolute_time(), ret;
+    absolutetime_to_nanoseconds(val, &ret);
+    return ret;
+}
diff --git a/src/libCom/osi/os/posix/osdMonotonic.c b/src/libCom/osi/os/posix/osdMonotonic.c
new file mode 100644
index 000000000..203702dd5
--- /dev/null
+++ b/src/libCom/osi/os/posix/osdMonotonic.c
@@ -0,0 +1,75 @@
+/*************************************************************************\
+* Copyright (c) 2015 Michael Davidsaver
+* EPICS BASE is distributed subject to a Software License Agreement found
+* in file LICENSE that is included with this distribution.
+\*************************************************************************/
+
+#define epicsExportSharedSymbols
+#include "dbDefs.h"
+#include "errlog.h"
+#define EPICS_EXPOSE_LIBCOM_MONOTONIC_PRIVATE
+#include "epicsTime.h"
+#include "generalTimeSup.h"
+
+static clockid_t osdMonotonicID;
+static epicsUInt64 osdMonotonicResolution;
+
+void osdMonotonicInit(void)
+{
+    unsigned i;
+clockid_t ids[] = {
+#ifdef CLOCK_MONOTONIC_RAW
+        CLOCK_MONOTONIC_RAW, /* Linux specific */
+#endif
+#ifdef CLOCK_HIGHRES
+        CLOCK_HIGHRES, /* solaris specific */
+#endif
+#ifdef CLOCK_MONOTONIC
+        CLOCK_MONOTONIC, /* Linux, RTEMS, and probably others */
+#endif
+    /* fallback and vxWorks, not actually monotonic, but always available */
+        CLOCK_REALTIME
+    };
+
+    for(i=0; i<NELEMENTS(ids); i++) {
+        epicsUInt64 res;
+        struct timespec ts;
+        int ret = clock_getres(ids[i], &ts);
+        if(ret) continue;
+
+        res  = ts.tv_sec;
+        res *= 1000000000;
+        res += ts.tv_nsec;
+
+        /* fetch the time once to see that it actually succeeds */
+        ret = clock_gettime(ids[i], &ts);
+        if(ret) continue;
+
+        osdMonotonicID = ids[i];
+        osdMonotonicResolution = res;
+        return;
+    }
+
+    errMessage(errlogMinor, "Warning: failed to setup monotonic time source\n");
+}
+
+epicsUInt64 epicsMonotonicResolution(void)
+{
+    return osdMonotonicResolution;
+}
+
+epicsUInt64 epicsMonotonicGet(void)
+{
+    struct timespec ts;
+    int ret = clock_gettime(osdMonotonicID, &ts);
+    if(ret) {
+        errlogPrintf("Warning: failed to fetch monotonic time %d %d\n",
+                     (int)osdMonotonicID, ret);
+        return 0;
+    } else {
+        epicsUInt64 ret = ts.tv_sec;
+        ret *= 1000000000;
+        ret += ts.tv_nsec;
+        return ret;
+    }
+}
diff --git a/src/libCom/osi/os/posix/osdTime.cpp b/src/libCom/osi/os/posix/osdTime.cpp
index d5fb05a1c..d56fc15d8 100644
--- a/src/libCom/osi/os/posix/osdTime.cpp
+++ b/src/libCom/osi/os/posix/osdTime.cpp
@@ -17,6 +17,7 @@
 
 #define epicsExportSharedSymbols
 #include "cantProceed.h"
+#define EPICS_EXPOSE_LIBCOM_MONOTONIC_PRIVATE
 #include "epicsTime.h"
 #include "generalTimeSup.h"
 
@@ -56,6 +57,8 @@ int clock_settime(clockid_t clock, const timespec *tp)
 static int timeRegister(void)
 {
     TIME_INIT;
+
+    osdMonotonicInit();
     return 1;
 }
 static int done = timeRegister();
diff --git a/src/libCom/osi/os/vxWorks/osdTime.cpp b/src/libCom/osi/os/vxWorks/osdTime.cpp
index 4db375fbb..fdfefb704 100644
--- a/src/libCom/osi/os/vxWorks/osdTime.cpp
+++ b/src/libCom/osi/os/vxWorks/osdTime.cpp
@@ -16,6 +16,7 @@
 #include <stdlib.h>
 #include <taskLib.h>
 
+#define EPICS_EXPOSE_LIBCOM_MONOTONIC_PRIVATE
 #include "epicsTime.h"
 #include "osiNTPTime.h"
 #include "osiClockTime.h"
@@ -63,6 +64,7 @@ static int timeRegister(void)
     } else {
         ClockTime_Init(CLOCKTIME_NOSYNC);
     }
+    osdMonotonicInit();
     return 1;
 }
 static int done = timeRegister();
diff --git a/src/libCom/test/epicsTimeTest.cpp b/src/libCom/test/epicsTimeTest.cpp
index 55ad43cdd..8eb8de6d4 100644
--- a/src/libCom/test/epicsTimeTest.cpp
+++ b/src/libCom/test/epicsTimeTest.cpp
@@ -38,12 +38,53 @@ static const unsigned uSecPerSec = 1000u * mSecPerSec;
 static const unsigned nSecPerSec = 1000u * uSecPerSec;
 static const double precisionEPICS = 1.0 / nSecPerSec;
 
+static void crossCheck(double delay)
+{
+    double mindelta = 2*epicsMonotonicResolution()*1e-9,
+            tres = epicsThreadSleepQuantum();
+    epicsUInt64 A = epicsMonotonicGet();
+    epicsThreadSleep(delay);
+    epicsUInt64 B = epicsMonotonicGet();
+
+    double actual = (B-A)*1e-9, percent;
+
+    if(mindelta<tres*2)
+        mindelta = tres*2;
+    if(delay<mindelta)
+        delay = mindelta;
+
+    percent = (delay-actual)/delay*100.0;
+
+    testOk(fabs(percent)<1000.0, "crossCheck(%f) actual %f (%f %%)",
+           delay, actual, percent);
+}
+
+static void testMonotonic()
+{
+    crossCheck(2.1); /* greater than 2 so that seconds value is different */
+    crossCheck(0.1);
+    crossCheck(0.01);
+    crossCheck(0.001);
+    crossCheck(epicsThreadSleepQuantum());
+
+    testDiag("Resolution %u ns", (unsigned)epicsMonotonicResolution());
+
+    epicsUInt64 A = epicsMonotonicGet();
+    epicsThreadSleep(0.0);
+    epicsUInt64 B = epicsMonotonicGet();
+    testDiag("epicsThreadSleep(0.0) Delta %u ns", (unsigned)(B-A));
+
+    A = epicsMonotonicGet();
+    B = epicsMonotonicGet();
+    testDiag("Small Delta %u ns", (unsigned)(B-A));
+}
+
 MAIN(epicsTimeTest)
 {
     const int wasteTime = 100000;
     const int nTimes = 10;
 
-    testPlan(17 + nTimes * 19);
+    testPlan(22 + nTimes * 19);
 
     try {
         const epicsTimeStamp epochTS = {0, 0};
@@ -241,5 +282,7 @@ MAIN(epicsTimeTest)
         testFail("OS time_t conversion exception for value 10 years hence");
     }
 
+    testMonotonic();
+
     return testDone();
 }

From cccab7437fb4d7d33fadff6c81e63c4e8f53647a Mon Sep 17 00:00:00 2001
From: Michael Davidsaver <mdavidsaver@gmail.com>
Date: Mon, 11 Jan 2016 21:49:49 -0500
Subject: [PATCH 2/7] move EPICS_EXPOSE_LIBCOM_MONOTONIC_PRIVATE before all
 local includes

---
 src/libCom/osi/os/Darwin/osdMonotonic.c | 2 +-
 src/libCom/osi/os/Darwin/osdTime.cpp    | 2 +-
 src/libCom/osi/os/RTEMS/osdTime.cpp     | 2 +-
 src/libCom/osi/os/WIN32/osdMonotonic.c  | 2 +-
 src/libCom/osi/os/iOS/osdMonotonic.c    | 2 +-
 src/libCom/osi/os/posix/osdMonotonic.c  | 2 +-
 src/libCom/osi/os/posix/osdTime.cpp     | 2 +-
 7 files changed, 7 insertions(+), 7 deletions(-)

diff --git a/src/libCom/osi/os/Darwin/osdMonotonic.c b/src/libCom/osi/os/Darwin/osdMonotonic.c
index 50ca82ef6..9ce14fa8e 100644
--- a/src/libCom/osi/os/Darwin/osdMonotonic.c
+++ b/src/libCom/osi/os/Darwin/osdMonotonic.c
@@ -8,9 +8,9 @@
 #include <mach/mach_time.h>
 
 #define epicsExportSharedSymbols
+#define EPICS_EXPOSE_LIBCOM_MONOTONIC_PRIVATE
 #include "dbDefs.h"
 #include "errlog.h"
-#define EPICS_EXPOSE_LIBCOM_MONOTONIC_PRIVATE
 #include "epicsTime.h"
 #include "generalTimeSup.h"
 
diff --git a/src/libCom/osi/os/Darwin/osdTime.cpp b/src/libCom/osi/os/Darwin/osdTime.cpp
index 7bddc7da2..315caeb9b 100644
--- a/src/libCom/osi/os/Darwin/osdTime.cpp
+++ b/src/libCom/osi/os/Darwin/osdTime.cpp
@@ -15,11 +15,11 @@
 #include <mach/mach.h>
 #include <mach/clock.h>
 
+#define EPICS_EXPOSE_LIBCOM_MONOTONIC_PRIVATE
 #include "osiSock.h"
 
 #define epicsExportSharedSymbols
 #include "cantProceed.h"
-#define EPICS_EXPOSE_LIBCOM_MONOTONIC_PRIVATE
 #include "epicsTime.h"
 #include "generalTimeSup.h"
 
diff --git a/src/libCom/osi/os/RTEMS/osdTime.cpp b/src/libCom/osi/os/RTEMS/osdTime.cpp
index a9d5c2ea6..1350c1cf2 100644
--- a/src/libCom/osi/os/RTEMS/osdTime.cpp
+++ b/src/libCom/osi/os/RTEMS/osdTime.cpp
@@ -12,6 +12,7 @@
 #include <sys/types.h>
 #include <sys/socket.h>
 
+#define EPICS_EXPOSE_LIBCOM_MONOTONIC_PRIVATE
 #include <epicsStdio.h>
 #include <rtems.h>
 #include <errno.h>
@@ -20,7 +21,6 @@
 #include <sys/socket.h>
 #include <netinet/in.h>
 #include <rtems/rtems_bsdnet_internal.h>
-#define EPICS_EXPOSE_LIBCOM_MONOTONIC_PRIVATE
 #include "epicsTime.h"
 #include "osdTime.h"
 #include "osiNTPTime.h"
diff --git a/src/libCom/osi/os/WIN32/osdMonotonic.c b/src/libCom/osi/os/WIN32/osdMonotonic.c
index 342ee7d60..e7da25da4 100644
--- a/src/libCom/osi/os/WIN32/osdMonotonic.c
+++ b/src/libCom/osi/os/WIN32/osdMonotonic.c
@@ -7,9 +7,9 @@
 #include <windows.h>
 
 #define epicsExportSharedSymbols
+#define EPICS_EXPOSE_LIBCOM_MONOTONIC_PRIVATE
 #include "dbDefs.h"
 #include "errlog.h"
-#define EPICS_EXPOSE_LIBCOM_MONOTONIC_PRIVATE
 #include "epicsTime.h"
 #include "generalTimeSup.h"
 
diff --git a/src/libCom/osi/os/iOS/osdMonotonic.c b/src/libCom/osi/os/iOS/osdMonotonic.c
index 0c2c7718f..0eab29c91 100644
--- a/src/libCom/osi/os/iOS/osdMonotonic.c
+++ b/src/libCom/osi/os/iOS/osdMonotonic.c
@@ -7,9 +7,9 @@
 #import <mach/mach_time.h>
 
 #define epicsExportSharedSymbols
+#define EPICS_EXPOSE_LIBCOM_MONOTONIC_PRIVATE
 #include "dbDefs.h"
 #include "errlog.h"
-#define EPICS_EXPOSE_LIBCOM_MONOTONIC_PRIVATE
 #include "epicsTime.h"
 #include "generalTimeSup.h"
 
diff --git a/src/libCom/osi/os/posix/osdMonotonic.c b/src/libCom/osi/os/posix/osdMonotonic.c
index 203702dd5..00c9c2871 100644
--- a/src/libCom/osi/os/posix/osdMonotonic.c
+++ b/src/libCom/osi/os/posix/osdMonotonic.c
@@ -5,9 +5,9 @@
 \*************************************************************************/
 
 #define epicsExportSharedSymbols
+#define EPICS_EXPOSE_LIBCOM_MONOTONIC_PRIVATE
 #include "dbDefs.h"
 #include "errlog.h"
-#define EPICS_EXPOSE_LIBCOM_MONOTONIC_PRIVATE
 #include "epicsTime.h"
 #include "generalTimeSup.h"
 
diff --git a/src/libCom/osi/os/posix/osdTime.cpp b/src/libCom/osi/os/posix/osdTime.cpp
index d56fc15d8..1952babd9 100644
--- a/src/libCom/osi/os/posix/osdTime.cpp
+++ b/src/libCom/osi/os/posix/osdTime.cpp
@@ -13,11 +13,11 @@
 #include <string.h>
 #include <errno.h>
 
+#define EPICS_EXPOSE_LIBCOM_MONOTONIC_PRIVATE
 #include "osiSock.h"
 
 #define epicsExportSharedSymbols
 #include "cantProceed.h"
-#define EPICS_EXPOSE_LIBCOM_MONOTONIC_PRIVATE
 #include "epicsTime.h"
 #include "generalTimeSup.h"
 

From 1c00e79b6b0c45f020ede5a0b6806d3ae5b37ca4 Mon Sep 17 00:00:00 2001
From: Michael Davidsaver <mdavidsaver@gmail.com>
Date: Wed, 14 Jun 2017 17:02:10 +0200
Subject: [PATCH 3/7] monotonic: fix osx

---
 src/libCom/osi/os/Darwin/osdMonotonic.c | 14 ++++++++------
 1 file changed, 8 insertions(+), 6 deletions(-)

diff --git a/src/libCom/osi/os/Darwin/osdMonotonic.c b/src/libCom/osi/os/Darwin/osdMonotonic.c
index 9ce14fa8e..6f8cb85af 100644
--- a/src/libCom/osi/os/Darwin/osdMonotonic.c
+++ b/src/libCom/osi/os/Darwin/osdMonotonic.c
@@ -1,10 +1,10 @@
 /*************************************************************************\
-* Copyright (c) 2015 Michael Davidsaver
+* Copyright (c) 2017 Michael Davidsaver
 * EPICS BASE is distributed subject to a Software License Agreement found
 * in file LICENSE that is included with this distribution.
 \*************************************************************************/
 
-#include <kern/clock.h>
+#include <mach/mach.h>
 #include <mach/mach_time.h>
 
 #define epicsExportSharedSymbols
@@ -14,19 +14,21 @@
 #include "epicsTime.h"
 #include "generalTimeSup.h"
 
+/* see https://developer.apple.com/library/content/qa/qa1398/_index.html */
+static mach_timebase_info_data_t tbinfo;
+
 void osdMonotonicInit(void)
 {
-    /* no-op */
+    (void)mach_timebase_info(&tbinfo);
 }
 
 epicsUInt64 epicsMonotonicResolution(void)
 {
-    return 1; /* TODO, how to find ? */
+    return 1e-9 * tbinfo.numer / tbinfo.denom;
 }
 
 epicsUInt64 epicsMonotonicGet(void)
 {
     uint64_t val = mach_absolute_time(), ret;
-    absolutetime_to_nanoseconds(val, &ret);
-    return ret;
+    return val * tbinfo.numer / tbinfo.denom;
 }

From 06b2d4bb76c829f30bb0b4d4c4627a056671112d Mon Sep 17 00:00:00 2001
From: Michael Davidsaver <mdavidsaver@gmail.com>
Date: Mon, 21 Dec 2015 14:35:35 -0500
Subject: [PATCH 4/7] db/test: dbStressTest use monotonic

Conflicts:
	src/ioc/db/test/dbStressLock.c
---
 src/ioc/db/test/dbStressLock.c | 59 ++++++++++++++++------------------
 1 file changed, 28 insertions(+), 31 deletions(-)

diff --git a/src/ioc/db/test/dbStressLock.c b/src/ioc/db/test/dbStressLock.c
index 376587975..aed0116e0 100644
--- a/src/ioc/db/test/dbStressLock.c
+++ b/src/ioc/db/test/dbStressLock.c
@@ -27,7 +27,10 @@
 #include "epicsSpin.h"
 #include "epicsThread.h"
 #include "epicsMutex.h"
+#include "epicsEvent.h"
+#include "epicsMath.h"
 #include "dbCommon.h"
+#include "epicsTime.h"
 
 #include "dbLockPvt.h"
 #include "dbStaticLib.h"
@@ -40,10 +43,6 @@
 
 #include "xRecord.h"
 
-#if defined(CLOCK_REALTIME) && defined(CLOCK_MONOTONIC) && !defined(_WIN32)
-# define TIME_STATS
-#endif
-
 #define testIntOk1(A, OP, B) testOk((A) OP (B), "%s (%d) %s %s (%d)", #A, A, #OP, #B, B);
 #define testPtrOk1(A, OP, B) testOk((A) OP (B), "%s (%p) %s %s (%p)", #A, A, #OP, #B, B);
 
@@ -64,10 +63,9 @@ static dbCommon **precords;
 typedef struct {
     int id;
     unsigned long N[3];
-#ifdef TIME_STATS
     double X[3];
     double X2[3];
-#endif
+    double min[3], max[3];
 
     unsigned int done;
     epicsEventId donevent;
@@ -158,25 +156,19 @@ void doreTarget(workerPriv *p)
 static
 void worker(void *raw)
 {
-#ifdef TIME_STATS
-    struct timespec before;
-#endif
+    unsigned init = 1;
     workerPriv *priv = raw;
 
     testDiag("worker %d is %p", priv->id, epicsThreadGetIdSelf());
 
-#ifdef TIME_STATS
-    clock_gettime(CLOCK_MONOTONIC, &before);
-#endif
-
     while(!priv->done) {
+        epicsUInt64 after, before;
         double sel = getRand();
-#ifdef TIME_STATS
-        struct timespec after;
         double duration;
-#endif
-
         int act;
+
+        before = epicsMonotonicGet();
+
         if(sel<0.33) {
             doSingle(priv);
             act = 0;
@@ -188,19 +180,18 @@ void worker(void *raw)
             act = 2;
         }
 
-#ifdef TIME_STATS
-        clock_gettime(CLOCK_MONOTONIC, &after);
-
-        duration = (double)((long)after.tv_nsec - (long)before.tv_nsec);
-        duration *= 1e-9;
-        duration += (double)(after.tv_sec - before.tv_sec);
-#endif
+        after = epicsMonotonicGet();
+        duration = (after-before)*1e-9;
 
         priv->N[act]++;
-#ifdef TIME_STATS
         priv->X[act] += duration;
         priv->X2[act] += duration*duration;
-#endif
+        if(duration<priv->min[act] || init) {
+            priv->min[act] = duration;
+            init = 0;
+        }
+        if(duration>priv->max[act])
+            priv->max[act] = duration;
     }
 
     epicsEventMustTrigger(priv->donevent);
@@ -333,12 +324,18 @@ MAIN(dbStressTest)
 
     testDiag("Statistics");
     for(i=0; i<nworkers; i++) {
+        double avg[3], std[3];
+        unsigned j;
         testDiag("Worker %u", i);
-        testDiag("N = %lu %lu %lu", priv[i].N[0], priv[i].N[1], priv[i].N[2]);
-#ifdef TIME_STATS
-        testDiag("X = %g %g %g", priv[i].X[0], priv[i].X[1], priv[i].X[2]);
-        testDiag("X2= %g %g %g", priv[i].X2[0], priv[i].X2[1], priv[i].X2[2]);
-#endif
+        for(j=0; j<3; j++) {
+            avg[j] = priv[i].X[j]/priv[i].N[j];
+            std[j] = sqrt( (priv[i].X2[j]/priv[i].N[j]) - avg[j]*avg[j] );
+        }
+        testDiag("N = %lu\t%lu\t%lu", priv[i].N[0], priv[i].N[1], priv[i].N[2]);
+        testDiag("AVG = %g us\t%g us\t%g us", avg[0]*1e6, avg[1]*1e6, avg[2]*1e6);
+        testDiag("STD = %g us\t%g us\t%g us", std[0]*1e6, std[1]*1e6, std[2]*1e6);
+        testDiag("MIN = %g us\t%g us\t%g us", priv[i].min[0]*1e6, priv[i].min[1]*1e6, priv[i].min[2]*1e6);
+        testDiag("MAX = %g us\t%g us\t%g us", priv[i].max[0]*1e6, priv[i].max[1]*1e6, priv[i].max[2]*1e6);
 
         testOk1(priv[i].N[0]>0);
         testOk1(priv[i].N[1]>0);

From 62db42bf356b3186d8caedd6df0c26bbede59830 Mon Sep 17 00:00:00 2001
From: Andrew Johnson <anj@aps.anl.gov>
Date: Mon, 23 Oct 2017 11:27:51 -0500
Subject: [PATCH 5/7] Delete unused variable

---
 src/libCom/osi/os/Darwin/osdMonotonic.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/src/libCom/osi/os/Darwin/osdMonotonic.c b/src/libCom/osi/os/Darwin/osdMonotonic.c
index 6f8cb85af..2f81d002b 100644
--- a/src/libCom/osi/os/Darwin/osdMonotonic.c
+++ b/src/libCom/osi/os/Darwin/osdMonotonic.c
@@ -29,6 +29,6 @@ epicsUInt64 epicsMonotonicResolution(void)
 
 epicsUInt64 epicsMonotonicGet(void)
 {
-    uint64_t val = mach_absolute_time(), ret;
+    uint64_t val = mach_absolute_time();
     return val * tbinfo.numer / tbinfo.denom;
 }

From a1d2f337f44e840493a5aa6e5bff74c2833529a7 Mon Sep 17 00:00:00 2001
From: Andrew Johnson <anj@aps.anl.gov>
Date: Mon, 23 Oct 2017 11:30:29 -0500
Subject: [PATCH 6/7] Initial VxWorks support code

Implemented for both PowerPC and i86.
Builds, but not tested yet.
---
 src/libCom/osi/os/vxWorks/osdMonotonic.c | 92 ++++++++++++++++++++++++
 1 file changed, 92 insertions(+)
 create mode 100644 src/libCom/osi/os/vxWorks/osdMonotonic.c

diff --git a/src/libCom/osi/os/vxWorks/osdMonotonic.c b/src/libCom/osi/os/vxWorks/osdMonotonic.c
new file mode 100644
index 000000000..6a7abadbf
--- /dev/null
+++ b/src/libCom/osi/os/vxWorks/osdMonotonic.c
@@ -0,0 +1,92 @@
+/*************************************************************************\
+* Copyright (c) 2017 UChicago Argonne LLC, as Operator of Argonne
+*     National Laboratory.
+* EPICS BASE is distributed subject to a Software License Agreement found
+* in file LICENSE that is included with this distribution.
+\*************************************************************************/
+
+#define _VSB_CONFIG_FILE <../lib/h/config/vsbConfig.h>
+
+#include <vxWorks.h>
+
+#define EPICS_EXPOSE_LIBCOM_MONOTONIC_PRIVATE
+#include "epicsTypes.h"
+#include "epicsTime.h"
+#include "epicsFindSymbol.h"
+
+
+#define NS_PER_SEC 1000000000
+
+union timebase {
+    UINT32 u32[2];  /* vxTimeBaseGet() */
+    INT64 i64;      /* pentiumTscGet64() */
+    UINT64 u64;     /* epicsMonotonicGet() */
+};
+
+static epicsUInt64 ticksPerSec;
+
+
+#if CPU_FAMILY == PPC
+#include <arch/ppc/vxPpcLib.h>
+
+#define TIMEBASEGET(TB) \
+    vxTimeBaseGet(&TB.u32[0], &TB.u32[1])
+
+typedef epicsUInt64 (*sysTimeBaseFreq_t)(void);
+
+void osdMonotonicInit(void)
+{
+    sysTimeBaseFreq_t sysTimeBaseFreq =
+        (sysTimeBaseFreq_t) epicsFindSymbol("_sysTimeBaseFreq");
+
+    if (sysTimeBaseFreq) {
+        ticksPerSec = sysTimeBaseFreq();
+        return;
+    }
+
+    printf("Warning: BSP routine sysTimeBaseFreq() not found,\n"
+        "can't set up monotonic time source.\n");
+    ticksPerSec = 0;
+}
+
+
+#elif CPU_FAMILY == I80X86
+
+#include <arch/i86/pentiumLib.h>
+#include <hwif/cpu/arch/i86/vxCpuIdLib.h>
+
+#define TIMEBASEGET(TB) \
+    pentiumTscGet64(&TB.i64)
+
+void osdMonotonicInit(void)
+{
+    ticksPerSec = vxCpuIdGetFreq();
+
+    if (!ticksPerSec)
+        printf("Warning: Failed to set up monotonic time source.\n");
+}
+
+
+#else
+  #error CPU Family not supported yet!
+#endif
+
+
+epicsUInt64 epicsMonotonicResolution(void)
+{
+    if (!ticksPerSec)
+        return 0;
+
+    return NS_PER_SEC / ticksPerSec;
+}
+
+epicsUInt64 epicsMonotonicGet(void)
+{
+    union timebase tbNow;
+
+    if (!ticksPerSec)
+        return 0;
+
+    TIMEBASEGET(tbNow);
+    return tbNow.u64 / (ticksPerSec / NS_PER_SEC);
+}

From 49d638be979ea7fad86d6d68e98d692ad9e62e1e Mon Sep 17 00:00:00 2001
From: Andrew Johnson <anj@aps.anl.gov>
Date: Fri, 27 Oct 2017 15:17:38 -0500
Subject: [PATCH 7/7] VxWorks osdMonotonic implementation

PowerPC time-base frequencies are 32-bit.
Adjust when warnings are printed.
Use long double to calculate time from time-base.
---
 src/libCom/osi/os/vxWorks/osdMonotonic.c | 47 +++++++++++++++++-------
 1 file changed, 34 insertions(+), 13 deletions(-)

diff --git a/src/libCom/osi/os/vxWorks/osdMonotonic.c b/src/libCom/osi/os/vxWorks/osdMonotonic.c
index 6a7abadbf..e0c6b2278 100644
--- a/src/libCom/osi/os/vxWorks/osdMonotonic.c
+++ b/src/libCom/osi/os/vxWorks/osdMonotonic.c
@@ -8,11 +8,11 @@
 #define _VSB_CONFIG_FILE <../lib/h/config/vsbConfig.h>
 
 #include <vxWorks.h>
+#include <stdio.h>
 
 #define EPICS_EXPOSE_LIBCOM_MONOTONIC_PRIVATE
 #include "epicsTypes.h"
 #include "epicsTime.h"
-#include "epicsFindSymbol.h"
 
 
 #define NS_PER_SEC 1000000000
@@ -23,30 +23,35 @@ union timebase {
     UINT64 u64;     /* epicsMonotonicGet() */
 };
 
-static epicsUInt64 ticksPerSec;
-
 
 #if CPU_FAMILY == PPC
 #include <arch/ppc/vxPpcLib.h>
+#include "epicsFindSymbol.h"
+
+/* On PowerPC the timebase counter runs at a rate related to the
+ * bus clock and its frequency should always fit into a UINT32.
+ */
+
+static epicsUInt32 ticksPerSec;
 
 #define TIMEBASEGET(TB) \
     vxTimeBaseGet(&TB.u32[0], &TB.u32[1])
 
-typedef epicsUInt64 (*sysTimeBaseFreq_t)(void);
-
 void osdMonotonicInit(void)
 {
+    typedef epicsUInt32 (*sysTimeBaseFreq_t)(void);
     sysTimeBaseFreq_t sysTimeBaseFreq =
         (sysTimeBaseFreq_t) epicsFindSymbol("_sysTimeBaseFreq");
 
     if (sysTimeBaseFreq) {
         ticksPerSec = sysTimeBaseFreq();
-        return;
-    }
 
-    printf("Warning: BSP routine sysTimeBaseFreq() not found,\n"
-        "can't set up monotonic time source.\n");
-    ticksPerSec = 0;
+        if (!ticksPerSec)
+            printf("Warning: Failed to set up monotonic time source.\n");
+            /* Warn here only if the BSP routine exists but returned 0 */
+    }
+    else
+        ticksPerSec = 0;    /* Warn on first use */
 }
 
 
@@ -55,6 +60,12 @@ void osdMonotonicInit(void)
 #include <arch/i86/pentiumLib.h>
 #include <hwif/cpu/arch/i86/vxCpuIdLib.h>
 
+/* On Intel the timebase counter frequency is returned by the OS as a
+ * UINT64. Some CPUs may count at multi-GHz rates so we need 64 bits.
+ */
+
+static epicsUInt64 ticksPerSec;
+
 #define TIMEBASEGET(TB) \
     pentiumTscGet64(&TB.i64)
 
@@ -68,7 +79,7 @@ void osdMonotonicInit(void)
 
 
 #else
-  #error CPU Family not supported yet!
+  #error This CPU family not supported yet!
 #endif
 
 
@@ -84,9 +95,19 @@ epicsUInt64 epicsMonotonicGet(void)
 {
     union timebase tbNow;
 
-    if (!ticksPerSec)
+    if (!ticksPerSec) {
+        static int warned = 0;
+
+        if (!warned) {
+            printf("Warning: Monotonic time source is not available.\n");
+            warned = 1;
+        }
         return 0;
+    }
 
     TIMEBASEGET(tbNow);
-    return tbNow.u64 / (ticksPerSec / NS_PER_SEC);
+    /* Using a long double for the calculation below to preserve
+     * as many bits in the mantissa as possible.
+     */
+    return ((long double) tbNow.u64) * NS_PER_SEC / ticksPerSec;
 }