From owner-freebsd-alpha  Thu Sep  5 13:49:40 2002
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Date: Thu, 5 Sep 2002 22:49:02 +0200
From: Bernd Walter <ticso@cicely9.cicely.de>
To: John Baldwin <jhb@FreeBSD.ORG>
Cc: ticso@cicely.de, freebsd-alpha@FreeBSD.ORG,
	Andrew Gallatin <gallatin@cs.duke.edu>
Subject: Re: ithread preemption
Message-ID: <20020905204901.GG13050@cicely9.cicely.de>
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References: <20020905201443.GD13050@cicely9.cicely.de> <XFMail.20020905163107.jhb@FreeBSD.org>
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On Thu, Sep 05, 2002 at 04:31:07PM -0400, John Baldwin wrote:
> 
> On 05-Sep-2002 Bernd Walter wrote:
> > OK - I have some basic understandig problems here.
> > 
> > Why should ithreads ever return to PAL?
> > Why is IPL raised while an ithread is running?
> > 
> > From what I understood before the interrupt handler, which is called
> > from PAL, just triggers the ithread, block the intline and returns.
> 
> Yes, but when you throw preemption into the mix you can switch to the
> actual ithread when you schedule it, and you don't return to the original
> interrupted thread until later.

Now I got it.

-- 
B.Walter              COSMO-Project         http://www.cosmo-project.de
ticso@cicely.de         Usergroup           info@cosmo-project.de


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