Path: utzoo!utgpu!jarvis.csri.toronto.edu!mailrus!ncar!tank!mimsy!chris
From: chris@mimsy.UUCP (Chris Torek)
Newsgroups: comp.unix.wizards
Subject: Re: Why UNIX doesn't support event?
Keywords: event, sleep, wakeup, signal
Message-ID: <15886@mimsy.UUCP>
Date: 10 Feb 89 06:44:54 GMT
References: <3921@cbnews.ATT.COM>
Distribution: usa
Organization: U of Maryland, Dept. of Computer Science, Coll. Pk., MD 20742
Lines: 15

In article <3921@cbnews.ATT.COM> rock@cbnews.ATT.COM (Y. Rock Lee) writes:
>Inside UNIX KERNEL, one can also sleep on an event(address)
>and expect to be waken up later by someone else.
>But, on the user level a process can only sleep on TIME.
>... What is the philosophy behind [this]?

Not true (one can also await a signal with pause() or sigpause()),
but the essential difference is that, while the kernel is multithreaded
and thus needs a fancy scheduling mechanism, Unix processes are
(normally) single-threaded so such a primitive is pointless.

You can always write your own, by writing your own scheduler.
-- 
In-Real-Life: Chris Torek, Univ of MD Comp Sci Dept (+1 301 454 7163)
Domain:	chris@mimsy.umd.edu	Path:	uunet!mimsy!chris