schizophrenic G5 ...

schizophrenic G5 ...

[Kevin Diggs]

Hi,

	I have a water cooled dual 2.5 GHz G5 (Powermac7,3). It has YDL 6.0 on 
it. Using the stock YDL 2.6.23 kernel this machine "appears" to work fine.

	After finally getting it to boot under 2.6.27, it will shut itself off 
if put under any significant load. And it is doing it very quickly. Like 
within a few seconds of becoming busy. I just discovered it is spitting 
out messages about "temperature way above maximum" (from therm_pm72.c).

	This one has the Panasonic cooling system. I have checked behind the 
cover and see no evidence of leaks.

	When put under load under the stock YDL kernel, the cpu fans will speed 
up for about 2 minutes. Then over the next minute or so they will slow 
down almost to idle. Thereafter a whirring sound can be heard every 15 
to 30 seconds lasting about 5 seconds. Which I am guessing is the pump? 
The exhaust air barely gets warm?

	Anyone have any ideas? Could the cooling system NOT be correctly 
thermally connected to the cpus?

kevin

Re: schizophrenic G5 ...

[Benjamin Herrenschmidt]

On Sun, 2008-12-21 at 16:11 -0800, Kevin Diggs wrote:
> Hi,
> 
> 	I have a water cooled dual 2.5 GHz G5 (Powermac7,3). It has YDL 6.0 on 
> it. Using the stock YDL 2.6.23 kernel this machine "appears" to work fine.
> 
> 	After finally getting it to boot under 2.6.27, it will shut itself off 
> if put under any significant load. And it is doing it very quickly. Like 
> within a few seconds of becoming busy. I just discovered it is spitting 
> out messages about "temperature way above maximum" (from therm_pm72.c).
> 
> 	This one has the Panasonic cooling system. I have checked behind the 
> cover and see no evidence of leaks.
> 
> 	When put under load under the stock YDL kernel, the cpu fans will speed 
> up for about 2 minutes. Then over the next minute or so they will slow 
> down almost to idle. Thereafter a whirring sound can be heard every 15 
> to 30 seconds lasting about 5 seconds. Which I am guessing is the pump? 
> The exhaust air barely gets warm?
> 
> 	Anyone have any ideas? Could the cooling system NOT be correctly 
> thermally connected to the cpus?

I have approx. the same here taking dust under the desk, I'll give it a
spin but i might have to wait a couple of days...

If mine works, then we'll have to run some more intensive debugging to
see what's going on.

Cheers,
Ben.

Re: schizophrenic G5 ...

[Kevin Diggs]

Benjamin Herrenschmidt wrote:
> On Sun, 2008-12-21 at 16:11 -0800, Kevin Diggs wrote:
> 
>>Hi,
>>
>>	I have a water cooled dual 2.5 GHz G5 (Powermac7,3). It has YDL 6.0 on 
>>it. Using the stock YDL 2.6.23 kernel this machine "appears" to work fine.
>>
>>	After finally getting it to boot under 2.6.27, it will shut itself off 
>>if put under any significant load. And it is doing it very quickly. Like 
>>within a few seconds of becoming busy. I just discovered it is spitting 
>>out messages about "temperature way above maximum" (from therm_pm72.c).
>>
>>	This one has the Panasonic cooling system. I have checked behind the 
>>cover and see no evidence of leaks.
>>
>>	When put under load under the stock YDL kernel, the cpu fans will speed 
>>up for about 2 minutes. Then over the next minute or so they will slow 
>>down almost to idle. Thereafter a whirring sound can be heard every 15 
>>to 30 seconds lasting about 5 seconds. Which I am guessing is the pump? 
>>The exhaust air barely gets warm?
>>
>>	Anyone have any ideas? Could the cooling system NOT be correctly 
>>thermally connected to the cpus?
> 
I would appreciate it if one of the many people on this list that are 
way more smarterer than me could tell me something like, "If this were 
true you would have toasted the cpus already!"
> 
> I have approx. the same here taking dust under the desk, I'll give it a
> spin but i might have to wait a couple of days...
> 
> If mine works, then we'll have to run some more intensive debugging to
> see what's going on.
> 
> Cheers,
> Ben.
> 
> 
Ben,

	I would appreciate it. I am now kinda afraid to turn the thing on.

Re: schizophrenic G5 ...

[Christian Krafft]

On Sun, 21 Dec 2008 16:11:43 -0800
Kevin Diggs <kevdig@hypersurf.com> wrote:

> Hi,
> 
> 	I have a water cooled dual 2.5 GHz G5 (Powermac7,3). It has
> YDL 6.0 on it. Using the stock YDL 2.6.23 kernel this machine
> "appears" to work fine.
> 
> 	After finally getting it to boot under 2.6.27, it will shut
> itself off if put under any significant load. And it is doing it very
> quickly. Like within a few seconds of becoming busy. I just
> discovered it is spitting out messages about "temperature way above
> maximum" (from therm_pm72.c).
> 

I have a very similar problem on my mac at work.
I don't know atm how to look up the critical temperature that is
fused. My mac reported only 55 degrees for the one cpu.
The critical temperature can be read from the device-tree if i remember
it correctly.
I heard that there exists a bootable CD which contains a tool to refuse
the CPU. Dont know where to download it, so my pragmatic solution was to
relocate the machine to a room with air conditioning ;-)
And I also run the ONE cpu at lowest frequency.

ck

-- 
Hi, I am a signature virus. Please copy me into your ~/.signature to
help me spread.

Re: schizophrenic G5 ...

[Benjamin Herrenschmidt]

> I have a very similar problem on my mac at work.
> I don't know atm how to look up the critical temperature that is
> fused. My mac reported only 55 degrees for the one cpu.
> The critical temperature can be read from the device-tree if i remember
> it correctly.
> I heard that there exists a bootable CD which contains a tool to refuse
> the CPU. Dont know where to download it, so my pragmatic solution was to
> relocate the machine to a room with air conditioning ;-)
> And I also run the ONE cpu at lowest frequency.

The calibration info is in an i2c EEPROM iirc, though we read it's
content via the device-tree.

Cheers,
Ben.

Re: schizophrenic G5 ...

[Kevin Diggs]

Christian Krafft wrote:
> On Sun, 21 Dec 2008 16:11:43 -0800
> Kevin Diggs <kevdig@hypersurf.com> wrote:
> 
> 
>>Hi,
>>
>>	I have a water cooled dual 2.5 GHz G5 (Powermac7,3). It has
>>YDL 6.0 on it. Using the stock YDL 2.6.23 kernel this machine
>>"appears" to work fine.
>>
>>	After finally getting it to boot under 2.6.27, it will shut
>>itself off if put under any significant load. And it is doing it very
>>quickly. Like within a few seconds of becoming busy. I just
>>discovered it is spitting out messages about "temperature way above
>>maximum" (from therm_pm72.c).
>>
> 
> 
> I have a very similar problem on my mac at work.
> I don't know atm how to look up the critical temperature that is
> fused. My mac reported only 55 degrees for the one cpu.
> The critical temperature can be read from the device-tree if i remember
> it correctly.
> I heard that there exists a bootable CD which contains a tool to refuse
> the CPU. Dont know where to download it, so my pragmatic solution was to
> relocate the machine to a room with air conditioning ;-)
> And I also run the ONE cpu at lowest frequency.
> 
> ck
> 

Critical temperature? If it is in the device tree are we sure it isn't 
(from the 970fx_thermal_diode_an, page 2, second paragraph):

In the PowerPC970FX family, the thermal diode is calibrated at a 
specified calibration temperature, usually around 70C, with no power on 
the chip, VDD = 0.0V, and 100 micro-amps being driven through the diode. 
The voltage across the diode is measured; it should be between 0.60V and 
0.80V. The measured voltage and temperature is stored in Thermal Diode 
Calibration fuse bits. A second lower temperature value is used to set 
the second calibration point, refer to the datasheet for this value.

On page 3 it also has:

Reading Thermal Diode Calibration Data Via JTAG
In order to access the Thermal Diode Calibration data stored in each 
processor, a sequence of JTAG commands must be issued, usually over the 
IIC bus. By using JTAG commands, the desired data will appear serially 
on the PowerPC970FX TDO pin or can be read using IIC. The detailed 
information on how to perform the read operation of the calibration 
registers is found in the PowerPC970FX User s Manual. Reading the 
thermal diode calibration register should be a one-time-only procedure. 
It is assumed that the Thermal Diode Calibration data stored in each 
processor will be captured and stored in system ROM for subsequent use.

kevin

Re: schizophrenic G5 ...

[Kevin Diggs]

Kevin Diggs wrote:
> Hi,
> 
>     I have a water cooled dual 2.5 GHz G5 (Powermac7,3). It has YDL 6.0 
> on it. Using the stock YDL 2.6.23 kernel this machine "appears" to work 
> fine.
> 
>     After finally getting it to boot under 2.6.27, it will shut itself 
> off if put under any significant load. And it is doing it very quickly. 
> Like within a few seconds of becoming busy. I just discovered it is 
> spitting out messages about "temperature way above maximum" (from 
> therm_pm72.c).
> 
>     This one has the Panasonic cooling system. I have checked behind the 
> cover and see no evidence of leaks.
> 
>     When put under load under the stock YDL kernel, the cpu fans will 
> speed up for about 2 minutes. Then over the next minute or so they will 
> slow down almost to idle. Thereafter a whirring sound can be heard every 
> 15 to 30 seconds lasting about 5 seconds. Which I am guessing is the 
> pump? The exhaust air barely gets warm?
> 
> 

If I run:

while true; do
	echo -n "cpu0\:  "; cat cpu0_temperature;
	echo -ne "\t"; cat cpu0_current; echo "";
	echo -n "cpu1\:  "; cat cpu1_temperature;
	echo -ne "\t"; cat cpu1_current;
	echo ""; sleep 1;
done

in one window and:

time /home/kevdig//r-970 -b4 -s1|nice -19 bzip2 -9v|dd bs=4b
count=400000 of=/dev/null

in two others I see different results between 2.6.23 and 2.6.27. Under 
the stock YDL 6.0 2.6.23 kernel, the temperatures level off at 50 and 
70. Peak temps are about 56 and 76. Idle temps are about 46 and 54.

Under 2.6.27, if I run ONE I see cpu1 temps range from 74 -> 89 -> 105
-> 111 -> 86. All one second apart. This happened pretty fast. Once I 
saw the 111 I ^c'ed the process. Can the temp really change that fast?

kevin