Re: [Ext-rt-dev] Re: [ANNOUNCE] Linux 2.6 Real Time Kernel

[hui]

On Tue, Oct 12, 2004 at 02:12:01PM -0700, Bill Huey wrote:
> On Tue, Oct 12, 2004 at 09:46:34PM +0200, Thomas Gleixner wrote:
> > enter_critical_section(TYPE, &var, &flags, whatever);
> > leave_critical_section(TYPE, &var, flags, whatever);
> 
> FreeBSD uses these things, but it they create severe pipeline stalls
> since they toggle interrupt flags on entry and exit. The current scheme
> in Linux with preempt_count use to be a curse when I was working on an
> equivalent implementation of there stuff at:
> 
> 	http://mmlinux.sf.net

Duh, I didn't finish the sentence. I meant this method above is nasty
filled with pipeline stalls. Don't know if that's what were saying, but
non-preemptable critical sections denoted by preempt_count must have some
kind of conceptual overlap with local_irq* functions. I use to curse the
seperation of the two since it made my own conception irregular, but I
have come to the conclusion that using relatively something light weight
like preempt_count() for that functionality instead. That's what I
meant. :)

bill

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