Meeting 21 July 2014

MAGEEC Meeting 21/07/2014 - Lymington

Review of action points from last time

Greg

• Script to generate PCA configurations
• 700 runs on 10 programs from BEEBS: training ~15s
• GC Q: Is the training exponential in programs
• Communal database needs SC input
• Auto-generation of benchmarks.

George

• DejaGnu framework
• ARM tools
• Cuttlefishes made. Programmers needed.
• Plackett-Burnham
  • Aliasing: not a high prority
  • Assuming factors independent
  • Aim it to find factors that actually matter
  • FFD on factors in cascaded manner to make number of tests tractable. Estimate ~2000 tests taking ~5h in parallel on 6 boards.

Stoil

• SG: Categorisation of BEEBS V2.0 not started

Generic issues

• [AB+JP+GF] Agreed method to compile in pseudo-random data sets in a generic manner

• GIMPL SSA headers missing from Ubuntu => MAGEEC build
• [JP+SG] Energy measurement code needs to be compilable.
• [SH] IDD header on measurement boards needs to be taller.

BEEBS

• Branching

Calibration of hardware

• From tech node analysis, perhaps 2% total variation in system energy (0.4% static power; 1-2% dynamic power) with temperature variation.
• Board-to-board variation needs more analysis.
  • [GC+JP] Measure and analyse the variation
• [JP] Actually measure board-to-board variation.
• We may need multiple runs of energy measurements across multiple boards to smooth the probability distribution.

BEEBS

• CMSIS-DSP tests
• BEEBS name across repository → “Bristol/Embecosm Energy Benchmark Suite”
• ARM CMSIS Maths + OS functions to add
• Push on self-validation with conditional compilation
  • Can turn off for code size analysis
  • Validation after the measurement STOP trigger
• AB 'gatekeeper' of gitbub repository. Push requests to him.

Case studies

• ARM – built out of CMSIS DSP functions
• CMSIS-RTOS – Keil RTX

Optimisations on a per-function basis

• Some kind of profiling to show the per-function distribution of execution costs is needed
  •  ? Is -O2 a good basis for counting instructions
• We may need to assume that time and energy are proportional for this.

Work going forward

Stoil

• Simulation of BEEBS for categorisation
  • AVR simulavr simulator → trace
  • qemu for ARM for each instruction. Also CGEN & Keil.
  • [2 week challenge] Analyse different evaluations of the BEEBS at three different levels, following this question:
•  ??? Do we categorise based on input program (generic) or instruction output (architecture-specific). What does the feature vector (intermediate level) expose from these for the generic level.
  • SC will help from 28/07/2014
  • gprof for dynamic execution count
  • Raspberry Pi may be a good compilation platform.

George

• • [2 weeks] AVR tests to do with new hardware

Greg

• Start moving on PCA of BEEBS.
  • Coordinate with Craig.

Oliver

• Short blog post

Simon

• Boards quotations
  • 100, 250, (500), 1000 volumes
  • Lead times