lce12

Posted on by Jean-Luc Aufranc (CNXSoft) - No Comments on SoC Power Measurement with ARM Energy Probes and Linux EAP Tools

SoC Power Measurement with ARM Energy Probes and Linux EAP Tools

Andy Green, TI Landing Team lead at Linaro,  gave an interesting presentation entitled “How to measure SoC power” at Linaro Connect Europe 2012. This talk was specifically aimed at software engineers, so that they know how to properly measure power consumption, and take actions to optimize the software to decrease it. In the first part of the presentation, he gives an overview of electronics basics with definition of voltage, load, current and power, units used for power measurements (Clue: you need to use Watts), and how voltage, current and power can be measured with voltmeters and ammeters. When you want to measure power in a rail, you would usually insert a shun resistor, use a multimeter and derive the power from the resistance and the measured voltage (P=V2/R). He also gives details about regulator efficiency, choosing measurement sampling… There are 4 common measurements strategies: DC IN – Easiest way, gives the complete […]

Posted on by Jean-Luc Aufranc (CNXSoft) - 5 Comments on Big.LITTLE Processing Implementations and Current Status

Big.LITTLE Processing Implementations and Current Status

There was a big,LITTLE mini-summit during Linaro Connect Europe 2012, where an update was given on current big.LITTLE implementations and the results of measurement of power vs performance. Big.LITTLE Processing Implementations Overview As briefly mentioned in “Versatile Express TC2 (2xA15, 3xA7) Development Board at ARM Techcon 2012“, there are 2 big.LITTLE implementations: In-kernel switcher (IKS) This implementation is already available through Linaro and only required minimal changed to the kernel as it mainly an augmentation to DVFS (Dynamic Voltage and Frequency Scaling) except instead of only adjusting voltage and frequency depending on the load, it will also move the load to different cores. The main drawback is that this implementation only uses half the cores. For example, on a 2x Cortex A15 / 2x Cortex A7 system, it can only use 2 cores at the same time (either A15 or A7 cores), as the load is managed between one type […]

Posted on by Jean-Luc Aufranc (CNXSoft) - 1 Comment on List of Android Benchmarks, Optimizations Results & Benchmarks Analysis

List of Android Benchmarks, Optimizations Results & Benchmarks Analysis

Linaro Connect Europe occurred in Copenhagen on Oct. 29 – Nov. 2 2012 (LCE12) and included 3 mini-summits about Android, big.LITTLE and ARMv8. Linaro has recently posted the presentation slides and I’ll have a look at a few of those slides in details and try to post information that I feel can be interesting. Today. I’ll go over the “Benchmarking and Optimization Opportunities” slides, where we can learn which Android Benchmarks Linaro use, how they’ve decreased benchmark results variance, which parts of the system are actually tested by benchmarks (profiling), and what they plan to do to further optimize Android on ARM. When I do some reviews, I usually simply use Antutu and Quadrant benchmarks to assess the performance of the devices, but Linaro uses many more benchmarks which I’ll list below. I’ll provide 2 links for each benchmark. The first link is to the official website and the other […]