On 10/02/15 06:49, Chris Clepper wrote:
In general, the ARM will do all sorts of things to keep energy usage to the bare minimum: Video decoding runs on dedicated DSP/GPU rather than the main cores, parts of the cores are shutdown, RAM is put to sleep and so on.
Using -nosleep on a root process at elevated could defeat enough of the low power safeguards as that is something an Android phone/tablet would never do. All of those devices have heatsinks just due to space constraints, and Apple ran afoul of customers due to excessive heat on a dual A8 based iPad.
Without any heat treatment on top of the CPU most of the heat flows through the PCB. So in some cases the issue wouldn't be with the ARM but some other part reaching its thermal limit (like a power regulator or RAM that have to be physically close to the CPU). The UDOO board's WiFi chip gets hotter than the ARM heatsink for example. Freescale recommend heat spreaders and sinks for all of their iMX.6 parts although not all of the low eval boards have them.
the Udoo I have has a very substantial heatsink, much much bigger than the older models, I guess this could be the reason.
Simon
The Pi 2 doesn't have much thermal cooling on the chip and the RAM is directly UNDER the CPU so the heat from both will largely go into the same place PCB. Maybe there is enough copper in the PCB to dissipate the heat, but the thermal docs I have from Freescale say it's not possible to do for a 5W+ quad A9.
On Mon, Feb 9, 2015 at 1:53 PM, Miller Puckettemsp@ucsd.edu wrote:
Interesting. Of course, it _should_ be thermally permitted to run all cores at speed - and the Pi folk are taking heat dissipation very seriously in their thinking. So my leaning would be to risk $35 on a week-long stress test using -nosleep. Hmm, time to order a machine...