From owner-freebsd-smp  Thu Apr 27 20:23: 4 2000
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Message-ID: <007101bfb0c2$a6fce9c0$5a5d0418@vista1.sdca.home.com>
From: "Jeremiah Gowdy" <jgowdy@home.com>
To: "Matthew Dillon" <dillon@apollo.backplane.com>
Cc: "Steve Passe" <smp@csn.net>,
	"James Housley" <jim@thehousleys.net>, <freebsd-smp@FreeBSD.ORG>
References: <200004271609.KAA24711@Ilsa.StevesCafe.com> <001d01bfb070$12236b00$5a5d0418@vista1.sdca.home.com> <200004280142.SAA07744@apollo.backplane.com>
Subject: Re: hlt instructions and temperature issues 
Date: Thu, 27 Apr 2000 20:34:25 -0700
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You said:
>     Umm... where'd you get the above code?   This is not the current
>     halt code for 3.x, 4.x, or 5.x.

That code was in :

> Luoqi Chen wrote:
> >
> > Index: swtch.s
> > ===================================================================
> > RCS file: /home/ncvs/src/sys/i386/i386/swtch.s,v
> > retrieving revision 1.91
> > diff -u -r1.91 swtch.s
> > --- swtch.s     2000/03/29 06:15:38     1.91
> > +++ swtch.s     2000/04/27 15:31:11
> > @@ -258,9 +258,14 @@
> >
> >  ENTRY(default_halt)
> >         sti
> > -#ifndef SMP
> > -       hlt                                     /* XXX:  until a wakeup
IPI */
> > +#ifdef SMP
> > +#ifdef CHEAP_TPR
> > +       movl    $0, lapic_tpr
> > +#else
> > +       andl    $~APIC_TPR_PRIO, lapic_tpr
> > +#endif /** CHEAP_TPR */
> >  #endif
> > +       hlt
> >         ret
> >
> I applied this patch to my 3.4-STABLE SMP cvs's yesterday afternoon.
> According to healthd my temps were 44.5 and 38.5 for the CPUs.  After
> rebooting they cooled down to 32.0 and 30.0.
>
> I guess the next question is, "Is this seriously impacting
> performance?"  Personaly a small hit is okay.

I was just saying that although he applied that patch to his SMP setup, and
it should work (I'm assuming), if he were to distribute that code or
something to others without SMP, it would double hlt on non-SMP setups.



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