This file relates the Successful curing of a heating problem during ltmodem driver usage.

============
Subject: heat problem with fedora core 2 + 2.6.7
From: Haris Saybasili <hsaybasili@gsu.edu.tr>
Date: Sat, 19 Jun 2004 18:59:33 +0300

Hi everyone..

I have just installed Fedora Core 2 on my Compaq Evo N800v and compiled
linux-2.6.7 as I did not like their modified kernel. 

I installed ltmodem without a problem. But, when I connect to the
internet the heat of the processor (p4 mobile 2.0) increases 10 - 13 C
degree (from 50-51C to 60-64C!), only with evolution and a mozilla (
no flash, no java... pure html without images) running! It bothers me a lot, I do not
want to burn my CPU.

With RedHat 9.0, and linux 2.4.22 (ltmodem-8.26a9), there were no
problem. 

There is a way to avoid this overheating? 

Any suggestions??

Thanks a lot...
==================
Subject: information about heat problem with fedora core 2 + linux 2.6.7
From: Haris Saybasili <haris.saybasili@laposte.net>
Date: Sat, 19 Jun 2004 20:57:35 +0300

I have just realized that this increase in temperature happens when the
ac adapter is online. When working with batteries, the temperature
remains normal.
===================
Subject: Re: information about heat problem with fedora core 2 + 2.6.7
From: Haris Saybasili <hsaybasili@gsu.edu.tr>
Date: Sun, 20 Jun 2004 13:43:16 +0300

No no, that is not the problem, I know that the processor' speed is
reduced in battery mode. I think there is a problem with ltmodem linux
2.6.x drivers.

Because of the modem driver, with linux 2.6.7, there is overheating when
connecting to the internet. After connecting to the internet, the heat
of the processor increases 12 C degrees, which can be very dangereous
(only kde running). After disconnecting, the heat decreases to normal
level. But this overheating occur only in the AC online mode. When I
disconnect, the temperature becomes normal. (ltmodem-2.6-alk-4 patched
with ltmodem-8.31alek).

For example now, I returned to my od 2.4.22 and everything is normal,
there is no overheating in battery mode nor in ac adapter online mode.
Now, I am connected by modem and the CPU temperature is 42 degree, with
evolution, mozilla, kde 3.2 and one konsole running. With 2.6.7, it was
64 degreees, even only with kde!!!

I wrote this, because maybe there is some problem in the ltmodem driver
with cpufreq or acpi drivers of the 2.6.x kernel. 

There are anybody experienced the same problem???
==========

Subject: Re: information about heat problem with fedora core 2 + 2.6.7
From: Haris Saybasili <hsaybasili@gsu.edu.tr>
Date: Sun, 20 Jun 2004 17:05:54 +0300

I had patched 2.4.22 for ACPI support. So, I use ACPI driver with 2.4.22
too, because my laptop does not support APM. Maybe I could not properly
configure 2.4.7. I took the config file from Fedora Core's modified
2.6.5 kernel, and disabled the unneeded drivers. 

Do you want me to send you my config file?

Thank you very much...

On Sun, 2004-06-20 at 16:51, Marvin Stodolsky wrote:
> Haris,
>   
> RE: 
> 
> 2.4.22 and everything is normal
> 
> ----------------
> The problem may be that under 2.6.7 kernel the laptop is using ACPI 
> power mode as constrated to APM under 2.4.22
> 
> If so, try a 2.6.7 bootup with
>   append="acpi=off"
> Report back.
> 
> MarvS
>  
==========
Subject: Re: information about heat problem with fedora core 2 + 2.6.7
From: Christoph Hebeisen <heby@heby.de>
Date: Sun, 20 Jun 2004 10:17:35 -0400

in my experience, the measurement of cpu temperature, fan speed etc. is 
not all that reliable in linux. hence my question: does the temperature 
increase at connect and decrease at disconnect instantaneously or 
gradually? an instantaneous increase/decrease would indicate that the 
modem driver is interfering with the temperature measurement (while 
annoying, not very worrysome) while a gradual change would indicate an 
actual temperature change.

christoph

Haris Saybasili wrote:
> No no, that is not the problem, I know that the processor' speed is
> reduced in battery mode. I think there is a problem with ltmodem linux
> 2.6.x drivers.
> 
> Because of the modem driver, with linux 2.6.7, there is overheating when
> connecting to the internet. After connecting to the internet, the heat
> of the processor increases 12 C degrees, which can be very dangereous
> (only kde running). After disconnecting, the heat decreases to normal
> level. But this overheating occur only in the AC online mode. When I
> disconnect, the temperature becomes normal. (ltmodem-2.6-alk-4 patched
> with ltmodem-8.31alek).
> 
> For example now, I returned to my od 2.4.22 and everything is normal,
> there is no overheating in battery mode nor in ac adapter online mode.
> Now, I am connected by modem and the CPU temperature is 42 degree, with
> evolution, mozilla, kde 3.2 and one konsole running. With 2.6.7, it was
> 64 degreees, even only with kde!!!
> 
> I wrote this, because maybe there is some problem in the ltmodem driver
> with cpufreq or acpi drivers of the 2.6.x kernel. 
> 
> There are anybody experienced the same problem???
=================

Subject: Re: information about heat problem with fedora core 2 + 2.6.7
From: Haris Saybasili <hsaybasili@gsu.edu.tr>
Date: Sun, 20 Jun 2004 18:46:08 +0300

Yeah you are right  is not very reliable, but the fans that are turning
at full speed justify it. I even received an alarm beep. 

The temperature changes gradually. For example, before the connection it
is 54 C degrees. After connecting, in about two minutes it becomes 64.
When I disconnect, it falls to 54 C degrees, again gradually. 

This problem is oly with 2.6.7. Actually i have not tried ltmodem
drivers with older 2.6.x kernels. Maybe they do not cause the same
problem.

And, as an additional information, when dialing (and during connection)
using linux 2.6.x drivers, there is a sound coming not from the speakers
(I am sure, I paste my ears to them :)), but I think from the power
supply. It is heard around the ac connection plug. When disconnected,
the sound disappears. 

Maybe there is some interference between ltmodem driver and the AC power
part of the ACPI driver in linux 2.6.x.
==========
Subject: Re: information about heat problem with fedora core 2 + 2.6.7
From: Christoph Hebeisen <heby@lphys.chem.utoronto.ca>
Date: Mon, 21 Jun 2004 01:33:31 -0400

ok, that sounds pretty conclusive, the actual cpu temperature is going up...

i haven't looked at the code in detail lately but to me it sounds 
unlikely (not totally inconceivable, though either) that the driver 
messes directly with the power status of your machine. the ltmodem 
driver needs some cpu time regularly at ms (or something on that order) 
intervals, though - it's possible that this activity prevents your 
computer from entering some power save mode it would normally go to 
(e.g. if the maximum cpu frequency is lower in battery mode than ac 
mode, then your description sounds like a very plausible result of this).

by the way, mozilla and kde are not exactly a good comparison - while 
they are big resource guzzlers, they typically aren't for constant cpu 
usage when they are just sitting there doing nothing (which they are, 
90% of the time at least). if my theory is right, then e.g. recoding a 
video with mencoder into a different audio/video format should bring 
your cpu to a boil in no time as well when on ac power. in that case, 
you might want to consider checking if your bios has the option to 
reduce the max. cpu frequency because that would indicate that your 
machine's cooling just isn't up to the job.

christoph
============



ok, that sounds pretty conclusive, the actual cpu temperature is going up...

i haven't looked at the code in detail lately but to me it sounds unlikely (not totally inconceivable, though either) that the driver messes directly with the power status of your machine. the ltmodem driver needs some cpu time regularly at ms (or something on that order) intervals, though - it's possible that this activity prevents your computer from entering some power save mode it would normally go to (e.g. if the maximum cpu frequency is lower in battery mode than ac mode, then your description sounds like a very plausible result of this).

by the way, mozilla and kde are not exactly a good comparison - while they are big resource guzzlers, they typically aren't for constant cpu usage when they are just sitting there doing nothing (which they are, 90% of the time at least). if my theory is right, then e.g. recoding a video with mencoder into a different audio/video format should bring your cpu to a boil in no time as well when on ac power. in that case, you might want to consider checking if your bios has the option to reduce the max. cpu frequency because that would indicate that your machine's cooling just isn't up to the job.

christoph

Haris Saybasili wrote:

> Yeah you are right  is not very reliable, but the fans that are turning
> at full speed justify it. I even received an alarm beep.
> The temperature changes gradually. For example, before the connection it
> is 54 C degrees. After connecting, in about two minutes it becomes 64.
> When I disconnect, it falls to 54 C degrees, again gradually.
> This problem is oly with 2.6.7. Actually i have not tried ltmodem
> drivers with older 2.6.x kernels. Maybe they do not cause the same
> problem.
>
> And, as an additional information, when dialing (and during connection)
> using linux 2.6.x drivers, there is a sound coming not from the speakers
> (I am sure, I paste my ears to them :)), but I think from the power
> supply. It is heard around the ac connection plug. When disconnected,
> the sound disappears.
> Maybe there is some interference between ltmodem driver and the AC power
> part of the ACPI driver in linux 2.6.x.
>
> On Sun, 2004-06-20 at 17:17, Christoph Hebeisen wrote:
>
>> in my experience, the measurement of cpu temperature, fan speed etc.
>
>
> is
>
>> not all that reliable in linux. hence my question: does the
>
>
> temperature
>
>> increase at connect and decrease at disconnect instantaneously or gradually? an instantaneous increase/decrease would indicate that the modem driver is interfering with the temperature measurement (while annoying, not very worrysome) while a gradual change would indicate an
>> actual temperature change.
>>
>> christoph
>>
>> Haris Saybasili wrote:
>>
>>> No no, that is not the problem, I know that the processor' speed is
>>> reduced in battery mode. I think there is a problem with ltmodem
>
>
> linux
>
>>> 2.6.x drivers.
>>>
>>> Because of the modem driver, with linux 2.6.7, there is overheating
>
>
> when
>
>>> connecting to the internet. After connecting to the internet, the
>
>
> heat
>
>>> of the processor increases 12 C degrees, which can be very
>
>
> dangereous
>
>>> (only kde running). After disconnecting, the heat decreases to
>
>
> normal
>
>>> level. But this overheating occur only in the AC online mode. When I
>>> disconnect, the temperature becomes normal. (ltmodem-2.6-alk-4
>
>
> patched
>
>>> with ltmodem-8.31alek).
>>>
>>> For example now, I returned to my od 2.4.22 and everything is
>
>
> normal,
>
>>> there is no overheating in battery mode nor in ac adapter online
>
>
> mode.
>
>>> Now, I am connected by modem and the CPU temperature is 42 degree,
>
>
> with
>
>>> evolution, mozilla, kde 3.2 and one konsole running. With 2.6.7, it
>
>
> was
>
>>> 64 degreees, even only with kde!!!
>>>
>>> I wrote this, because maybe there is some problem in the ltmodem
>
>
> driver
>
>>> with cpufreq or acpi drivers of the 2.6.x kernel.
>>> There are anybody experienced the same problem???
>>>

-- 
Christoph Hebeisen
Dept. of Chemistry, University of Toronto
80 St George St, Toronto, ON, M5S 3H6 Canada
Phone/Fax: +1 416 978 0366


=============
Subject: Re: [Fwd: Re: information about heat problem with fedora core 2 + 2.6.7]
From: Aleksey Kondratenko <alk@tut.by>
Date: Sun, 20 Jun 2004 23:55:01 +0300

Possible cause of overheating is 1000Hz timer in 2.6. This decreases
frequency in which ltmodem background task is run. 

Try the following patch:
--- lt_modem.c~	2004-06-20 23:52:50.000000000 +0300
+++ lt_modem.c	2004-06-07 02:19:16.000000000 +0300
@@ -247,7 +247,7 @@
 asmlinkage
 void lt_add_timer(asmlinkage void (*timerfunction)(unsigned long))
 {
-	timerList.expires = jiffies+1;
+	timerList.expires = jiffies+10;
 	timerList.function = __timer_wrapper;
 	timerList.data = (unsigned long)timerfunction;
 	add_timer(&timerList);

P.S: Include alk@tut.by in reply addresses.


> Reply to discuss@linmodems.oreg
=====================================
Subject: Re: heat.patch
From: Haris Saybasili <hsaybasili@gsu.edu.tr>
Date: Mon, 21 Jun 2004 10:39:30 +0300

I just tried it. It works, and it works very well :)) There is no
increase in temperature (It is 49-50C degrees). 8 minutes passed since I
connected, and everything is normal. I will report problems, if any. But
I think this patch solves the problem.

Thank you very much....

haris

===================================
From: Aleksey Kondratenko <alk@tut.by>

As we all know 2.6 uses 1Khz timers. 2.4 uses 100Hz.
This patch just sets background task maximim run frequency to be equal
to 2.4. I'm using this already a couple of weeks or so. No problems yet.

P.S. I also got report about unusually high CPU consumption
and this patch seems to solved the problem.