patch 9.0.1411: accuracy of profiling is not optimal
Problem: Accuracy of profiling is not optimal.
Solution: Use CLOCK_MONOTONIC if possible. (Ernie Rael, closes #12129)
diff --git a/runtime/doc/builtin.txt b/runtime/doc/builtin.txt
index 0bdeabf..ec680be 100644
--- a/runtime/doc/builtin.txt
+++ b/runtime/doc/builtin.txt
@@ -7150,7 +7150,8 @@
call MyFunction()
echo reltimestr(reltime(start))
< Note that overhead for the commands will be added to the time.
- The accuracy depends on the system.
+ The accuracy depends on the system. Use reltimefloat() for the
+ greatest accuracy which is nanoseconds on some systems.
Leading spaces are used to make the string align nicely. You
can use split() to remove it. >
echo split(reltimestr(reltime(start)))[0]
@@ -10753,6 +10754,7 @@
postscript Compiled with PostScript file printing.
printer Compiled with |:hardcopy| support.
profile Compiled with |:profile| support.
+prof_nsec Profile results are in nano seconds.
python Python 2.x interface available. |has-python|
python_compiled Compiled with Python 2.x interface. |has-python|
python_dynamic Python 2.x interface is dynamically loaded. |has-python|
diff --git a/runtime/doc/repeat.txt b/runtime/doc/repeat.txt
index c8a0f5d..054b870 100644
--- a/runtime/doc/repeat.txt
+++ b/runtime/doc/repeat.txt
@@ -1148,9 +1148,10 @@
Profiling should give a good indication of where time is spent, but keep in
mind there are various things that may clobber the results:
-- The accuracy of the time measured depends on the gettimeofday() system
- function. It may only be as accurate as 1/100 second, even though the times
- are displayed in micro seconds.
+- The accuracy of the time measured depends on the gettimeofday(), or
+ clock_gettime if available, system function. The accuracy ranges from 1/100
+ second to nano seconds. With clock_gettime the times are displayed in nano
+ seconds, otherwise micro seconds. You can use `has("prof_nsec")`.
- Real elapsed time is measured, if other processes are busy they may cause
delays at unpredictable moments. You may want to run the profiling several