Experimental Physics and
Industrial Control System

"Jeff Hill" <[email protected]> · Tue, 22 Apr 2003 09:03:31 -0600

Hi Kate,

There are certainly easy ways to compute the difference between
two EPICS time stamps in seconds and you can also convert an
EPICS time stamp to an enhanced struct tm (ANSI C) which includes
the nanoseconds within a second in addition to the conventional
date, hour, and second fields. For example, the following code
measures the delay required to do some computationally intensive
task and also computes the current date and time.

epicsTime begin = epicsTime::getCurrent();
..
.. something computationally intensive
..
// compute the delay
double delayInSeconds = epicsTime::getCurrent() - begin;

// compute the date
local_tm_nano_sec localDAteAndTime = epicsTime::getCurrent();

However, perhaps what you are after is thread sleep scheduling
accuracy? If so, then you may be pleased with the addition of
"double epicsThreadSleepQuantum(void)" to the epicsThread API in
the next release of R3.14. This function returns the minimum
sleep interval obtainable from the local OS and has been very
useful for improving the accuracy of timers on average.

Jeff

> -----Original Message-----
> From: [email protected] [mailto:[email protected]] On
> Behalf Of Kate Feng
> Sent: Tuesday, April 22, 2003 8:25 AM
> To: [email protected]
> Subject: epicsTicksPerSecond for OSI ?
> 
> Hi,
> 
> As I am working on the OSI, I feel it would be handy to have
> the global
> variable "epicsTicksPerSecond" for the R3.14.1 OSI, which is
> equivalent
> to the vxTicksPerSecond variable in the VxWorks O.S..  Right
> now, the
> vxTicksPerSecond=60, and rtemsTicksPerSecond=50.  I did not
> check for
> other O.S.
> 
> 
> It is just a thought.  Maybe, it is called a different name.
> Or, maybe
> there is a reason not to have it.
> 
> 
> Thanks,
> Kate

Experimental Physics and Industrial Control System

Experimental Physics and
Industrial Control System