Re: epicsThreadSleep and epicsThreadSleepQuantum

["Konrad, Martin via Core-talk" <core-talk@aps.anl.gov>]

Hi,
> I started a tech-talk thread on this topic 11 years ago:
> 
> https://epics.anl.gov/tech-talk/2008/msg00987.php
Thanks Mark, I wasn't aware of this thread. I'm not aware of any way to
detect the sleep quantum reliably on modern machines either. The fact
that epicsThreadSleepQuantum() only works correctly on old machines
without high resolution timers suggests that we should avoid using it. I
think it would make sense to

a) Add a warning to the App Dev Guide.
b) Consider marking epicsThreadSleepQuantum(),
timerQueueActive::quantum(), and fdManager::quantum() as deprecated.
c) Remove the "(ppsl->period < 2 * quantum)" part of the test in [1].

If we want to sleep for a minimum amount of time we might want to call
nanosleep(0) instead. If I'm understanding the man page correctly this
should result at least in a context switch.

Thanks,

Martin

[1]
https://github.com/epics-base/epics-base/blob/3.15/src/ioc/db/dbScan.c#L822

-- 
Martin Konrad
Facility for Rare Isotope Beams
Michigan State University
640 South Shaw Lane
East Lansing, MI 48824-1321, USA
Tel. 517-908-7253
Email: konrad@frib.msu.edu