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Date:      Thu, 21 Sep 2000 21:08:48 -0400 (EDT)
From:      Kenneth Wayne Culver <culverk@wam.umd.edu>
To:        Mike Smith <msmith@FreeBSD.ORG>
Cc:        Warner Losh <imp@village.org>, current@FreeBSD.ORG
Subject:   Re: new idle_proc() makes my laptop very hot 
Message-ID:  <Pine.GSO.4.21.0009212108290.8542-100000@rac2.wam.umd.edu>
In-Reply-To: <200009212303.QAA62850@mass.osd.bsdi.com>

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My system fans always stay on... but again this is not in a laptop .. it
is on my regular pc... 


=================================================================
| Kenneth Culver              | FreeBSD: The best NT upgrade    |
| Unix Systems Administrator  | ICQ #: 24767726                 |
| and student at The          | AIM: muythaibxr                 |
| The University of Maryland, | Website: (Under Construction)   |
| College Park.	              | http://www.wam.umd.edu/~culverk/|
=================================================================

On Thu, 21 Sep 2000, Mike Smith wrote:

> > My laptop does seem to run *MUCH* warmer than before as well.  It runs
> > hot to begin with, but with the latest kernels it runs really hot.  It
> > used to get this hot only when I compiled -j 4.  I don't have ACPI
> > enabled and am using UP kernel.  There really needs to be a HLT in the
> > idle loop to keep idle machines cools.
> 
> If I remember from a discussion with John Baldwin, the reason we don't do 
> this (yet) is that HLT only wakes up when you take an interrupt, and 
> there are cases where we can't guarantee that we'll take an interrupt in 
> order to get us out of the HLT.
> 
> > The thermal management code, iirc, works in conjunction with this by
> > lower the clock rate when things aren't too loaded, but that is a
> > fairly complex thign to wait for.  It also seems to help mostly on
> > lightly loaded machines.  HLT helps more than you'd otherwise
> > think...c
> 
> HLT helps a lot, yes, but the thermal management code is responsible for 
> running the system fan(s) in ACPI mode as well as throttling the CPU.  In 
> some cases, that's a real issue (eg. I'm building the world now and 
> extremely worried about how hot this system is because I forgot to turn 
> ACPI off first. 8)
> 
> -- 
> ... every activity meets with opposition, everyone who acts has his
> rivals and unfortunately opponents also.  But not because people want
> to be opponents, rather because the tasks and relationships force
> people to take different points of view.  [Dr. Fritz Todt]
> 
> 
> 
> 
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