NetNews Usenet Archive 1992 #18/NN_1992_18.iso/spool/comp/unix/programm/4385

Internet Message Format | 1992-08-20 | 1.7 KB

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From: [e-mail] (Mark Evans)
Newsgroups: comp.unix.programmer
Subject: Re: Yielding a Timeslice
Message-ID: <[e-mail]>
Date: 20 Aug 92 13:28:24 GMT
References: <[e-mail]>
Organization: st
Lines: 26

In article <[e-mail]> [e-mail] (Jim Schwaiger) writes:
>Is there a standard (or commonly accepted) way for a program to yield
>its timeslice?  I have a program which checks on a condition in shared
>memory and would like to sleep (for less than 1 second) if that condition
>is not met, rather than waiting in the "hot" loop.
>
>Jim Schwaiger

I asked the same question recently.  There is no universal facility
across unices.  There is a Posix-defined facility named yield()
that some systems support.  If you are running on SVR4, you might
also look at priocntl(2).  It advertises, for real-time class processes,
the ability to "go to the back of the scheduling queue at the same
priority by resetting its rt_pri value to its current real-time
priority value."  An associate played with this briefly and observed
some very screwy behavior---a long 30ms average delay before returning.
We have no idea what's going on.

Also look at select() (BSD) or poll() (SVR[34]) which you can use
to implement a higher granular sleep based upon the system tick
frequency, which is usually 60 or 100 HZ.
--
Mark S. Evans                 Tandem Telecommunications Systems Inc.
Phone: [phone]           1255 W 15th St.
Fax:   [phone]           Plano, TX 75075
Mail:  [e-mail]