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From: ewoods@hemel.bull.co.uk (Eoin Woods)
Newsgroups: comp.realtime
Subject: Re: Spin locks
Message-ID: <1991Jan22.084616.16547@hemel.bull.co.uk>
Date: 22 Jan 91 08:46:16 GMT
References: <830@marvin.jpl.oz>
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Organization: Bull HN UK
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david@marvin.jpl.oz (David Magnay) writes:

>Can someone pls explain spinlocks. Are these a form of semaphore ?

Hmm, interesting question!
Basically yes.

The most simple spin-lock is a piece of code which would look something like:

	while (locked)
	   check_lock (lockA) ;

The essential thing about a spin-lock (if I can remember my real-time systems
courses) is that the process concerned loops until the lock it is waiting
for is released (and so can be inefficient in a real-time environment as
it uses resources and is stuck until the lock is released for it).

A good reference for this sort of information is :

	"Real-Time Systems Design", 2nd ed, Allworth and Zobel, Macmillan.

Eoin.
--
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