LHCb S&A Week: Some Issues Related to Computing Architectures

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Denis McDonald
7 years ago
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1 LHCb S&A Week: Some Issues Related to Computing Architectures beyond x86 November 16, 2015 LHCb S&A Week: Some Issues Related to Computing Architectures 0 / 5

2 CPU Possibilities Intel/AMD x86: Backward compatible instruction architectures descended from Intel s This is the architecture we all use. ARM: The Advanced RISC Machine architectures (originally developed by Acorn RISC Machines) have Reduced Instruction Set Computing. This is supposed to allow them to operate at a fraction of the power demand of CISC (Complex Instruction Set Computing) devices, such as x86 CPUs. Several vendors are entering the HPC market with ARM offerings. OpenPOWER: POWER8 is a family of superscalar symmetric multiprocessors based on the Power Architecture, and introduced in August 2013 at the Hot Chips conference. The designs are available for licensing under the OpenPOWER Foundation, which is the first time for such availability of IBM s highest-end processors. Why consider non-x86 architectures? They may provide more bang per buck. They may provide more bang per watt. They may provide better integration with accelerators (or not). Competition is healthy. It drives performance up and cost down. LHCb S&A Week: Some Issues Related to Computing Architectures 1 / 5

3 Some Accelerator Possibilities Intel s MIC (Many Integrated Core) Xeon Phi: The current generation boards have of order 60 Pentium generation CPU cores on a single board. The next generation is expected to share the same architecture and instruction set as ordinary Intel cores. Importantly, code produced by an ordinary compiler will also run on a Xeon Phi. With the current generation, a cross-compiler is required. nvidia GPGPUs: nvidia makes HPC boards with thousands of cores (and no video-out), gamer boards whose performance rivals that of their HPC boards, and credit-card sized modules with 256 CUDA cores as well as a Quad-core ARM processor and 4 GB of RAM. AMD FirePro GPUs: Focus seems to be gaming rather than HPC, but gaming performance and some OpenCL performance is often best-in-class. FPGAs: Field Programmable Gate Arrays might provide high performance for specialized computations. They can be combined with ARM processors on a single chip, sometimes called SoC (System on a Chip) devices. A prime vendor is Altera, recently purchased by Intel. LHCb S&A Week: Some Issues Related to Computing Architectures 2 / 5

4 Some Issues Adapting to a new software and computing model for Run 3 (and beyond) will require considering a large number of issues. In no particular order, we can consider a number. The list here is meant to start a discussion, nothing more. One set of issues is technical. languages algorithms speed of executions (in wall-clock time) operating systems portability of code sustainability of code In addition, cost should be big issue: cost of hardware cost of power/cooling cost of developing/maintaining software LHCb S&A Week: Some Issues Related to Computing Architectures 3 / 5

5 More Issues for Discussion Compatibility with the rest of HEP and the outside computing world introduces another set of considerations: must the EFF run the same hardware/software as offline? what hardware/software will be available on the HEP grid? what hardware/software will be available on commercial grids? what hardware/software will individual users have on their platforms? Some random considerations do we want to consider using proprietary hardware/software or do we want to use only open technologies? do we care about big-endian v. little-endian in terms of how code producing.dst/.root files interacts with code consuming these files? LHCb S&A Week: Some Issues Related to Computing Architectures 4 / 5

6 Final Thoughts Run 3 will require much more computing power than Run 2 to fully take advantage of the flood of data enabled by operating at 30 MHz with much higher pile-up. What R&D is required to understand what hardware will provide what benefits? What R&D is required to understand what software will provide what benefits? What is the trajectory for making decisions? LHCb S&A Week: Some Issues Related to Computing Architectures 5 / 5

GPU System Architecture. Alan Gray EPCC The University of Edinburgh

GPU System Architecture. Alan Gray EPCC The University of Edinburgh GPU System Architecture EPCC The University of Edinburgh Outline Why do we want/need accelerators such as GPUs? GPU-CPU comparison Architectural reasons for GPU performance advantages GPU accelerated systems