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From: Nicolas.Souchu@prism.uvsq.fr (Nicolas SOUCHU)
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Date: Mon, 3 Jun 1996 13:32:24 +0200 (MET DST)
Message-Id: <199606031132.NAA00333@angrand.prism.uvsq.fr>
To: hackers@freebsd.org
Subject: How to preempt the current process ?
Sender: owner-hackers@freebsd.org
X-Loop: FreeBSD.org
Precedence: bulk


An adapter that does not support interrupts must be polled. Then when
data is not available, I want the current process to be preempted
without sleeping, just scheduled (its state remains SRUN).

Is that enough? :

	s = splhigh ();
	mi_switch ();
	curpriority = p->p_usrpri;
	splx (s);

This is the sleep() code without queueing the process with
state=SSLEEP.

Secondly,

	what does mean :
			__asm__ ("":::"memory") ?

	This is the macro 'barrier()' in Linux.

Thanks in advance...

nicolas

--
Nicolas.Souchu@prism.uvsq.fr
Laboratoire PRiSM - Versailles, FRANCE
http://www.prism.uvsq.fr/public/son