Path: utzoo!attcan!uunet!oddjob!mimsy!chris
From: chris@mimsy.UUCP (Chris Torek)
Newsgroups: comp.unix.wizards
Subject: Re: P/V using SysV semop(2)
Keywords: fifo or lifo ?
Message-ID: <13204@mimsy.UUCP>
Date: 25 Aug 88 07:49:36 GMT
References: <1001@uwbull.uwbln.UUCP>
Distribution: comp
Organization: U of Maryland, Dept. of Computer Science, Coll. Pk., MD 20742
Lines: 12

In article <1001@uwbull.uwbln.UUCP> ckl@uwbln.UUCP (Christoph Kuenkel) writes:
>... is it impossible to implement P/V without starvation?

Yes.  At least one SysV implementation (probably two; I doubt yours is
the same as the other I heard of) will, when asked to switch among
three processes A,B,C, run in the order A,B,A,B,A,B,A,B....

This problem does not occur when using 4.3BSD's file locking primitive
to implement semaphores.
-- 
In-Real-Life: Chris Torek, Univ of MD Comp Sci Dept (+1 301 454 7163)
Domain:	chris@mimsy.umd.edu	Path:	uunet!mimsy!chris