PowerMac G5 quad-core, CPU A1 DIODE TEMP: 90.8 C (for example): How to handle? [Mac OS X behavior]

[Adrian Chadd]

Intel CPUs do the same thing these days. They do it without the OS assistance.

So maybe we need to add a thermal throttling module that inserts a
fixed number of HLT cycles with a timer, or something along those
lines, to try and enforce some form of processing duty cycle. (And
there'll be a minimum length to stay asleep regardless; as entering
sleep states does consume juice.)



-adrian


On 17 January 2015 at 21:36, Justin Hibbits <chmeeedalf at gmail.com> wrote:
> I noticed on my quad running OS X spins up the fans all the way down at
> 55C. Perhaps you can try that, set the initial multiplier to 300 or more.
> I can add a sysctl to change the multiplier, if that would help people.
>
> -Justin
> On Jan 17, 2015 2:25 PM, "Mark Millard" <markmi at dsl-only.net> wrote:
>
>> Looks like only Justin and Nathan got the graph (since I directly sent the
>> message to them but the mail list stripped it).
>>
>> ===
>> Mark Millard
>> markmi T dsl-only.net
>>
>> On 2015-Jan-17, at 02:20 PM, Mark Millard <markmi at dsl-only.net> wrote:
>>
>> I've included a picture of the graph of core temperatures from Mac OS X,
>> spanning a little over 6 minutes. The core temperature plots are colored
>> non-black.
>>
>> The "5 to 7" that I mentioned below is more like "3 to 12" over this time
>> interval.
>>
>>
>>
>>
>> ===
>> Mark Millard
>> markmi at dsl-only.net
>>
>> On 2015-Jan-17, at 02:04 PM, Mark Millard <markmi at dsl-only.net> wrote:
>>
>> Mac OS X 10.5 does force idle time of some form to keep core temperatures
>> down! My evidence is as follows.
>>
>> The application Temperature monitor does show me temperature records
>> (including graphs over time) under Mac OS X 10.5 for the G5. (No rpms.) It
>> displays the information as for cpu A 1&2 and cpu B 1&2 (instead of 0 and
>> 1). A2 is what it shows as a the hot one, matching FreeBSD's a1. I watched
>> with the current short-term temperature display updating once a second (set
>> via preferences).
>>
>> Once it reached around the low 90C range on A2 the temperature on A2
>> started oscillating, going from the mid/low 90C's down to the 60C's/70C's
>> and back up again, over and over, fairly rapidly. But the graph of the
>> temperatures for all the cores shows all the CPU/core temperatures as
>> oscillating in matching timing.
>>
>> So I conclude that Mac OS X is doing something to give all the CPUs/cores
>> time to cool down as soon as any one of them gets too hot.
>>
>> So I do not expect Mac OS X to automatically power down, it has already
>> been far longer than it takes for FreeBSD to shutdown with the patched
>> RPM/cooling code. Menu meters shows the cores as fully used (mostly 100%,
>> occasional 99%). They are mostly running 6 of my double/long-long HINT
>> benchmark variants built various ways with parameter values input that are
>> designed for long runs. (HINT is memory/CPU limited until it causes
>> noticeable paging. But I've configured to not page with the 16GB of RAM
>> avilable.)
>>
>> So far the maximum temperature is 95.8C, and that is on A2. The next
>> highest core is A1 at 81.2C so far. During this oscillation A2's minumum is
>> 60.7C so far.
>>
>> There is a pattern to the drops: there is a sequence of 5 to 7 in a row
>> where the drop starts back up almost immediately but then there is a longer
>> duration with the temperatures staying down before it starts back up again.
>> After the longer duration drop the temperature rise is not as rapid so it
>> is longer until the next forced-drop.
>>
>> For the 5-7 in a row they tend to get somewhat closer together the further
>> into the sequence. It may be that the time between triggers the longer
>> cooling duration.
>>
>> The G5 has been kept busy for well over an hour, far longer than FreeBSD
>> did for "make -j 8 buildworld buildkernel"
>>
>> ===
>> Mark Millard
>> markmi at dsl-only.net
>>
>> <ShortTermTempGraph.jpg>
>>
>>
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