Conference title1 A New Methodology for Studying Realistic Processors in Computer Science Degrees Crispín Gómez, María E. Gómez y Julio Sahuquillo DISCA. Technical University of Valencia DSI. University of Castilla-La Mancha

2 Outline Motivation Simulator Proposed Methodology Case Study Conclusions

3 Motivation Astonishingly quick evolution of processor architecture: Teaching should cover from the basics to the most realistic up-to-date concepts In-Order Execution Superscalar Out-Of-Order Execution ManycoreMulticore POWER

4 Motivation Current designs imply a big complexity Out-Of-order complex cores Multi-level memory hierarchy On-chip Interconnection network

5 Outline Motivation Simulator Proposed Methodology Case Study Conclusions

6 Simulator Multi2Sim: multicore and multithreaded X86 binary compatibility Application-only Free simulator: Open source project – Widely used on research –Academia –Industry

7 Simulator – Cores CPU: 6-staged pipelined processors, out-of-order execution – Execution stage maybe customized to be multicycle. Speculative execution Three mutithreading paradigms are supported: –Coarse grain, fine grain, simultaneous multithreading All microarchitectural parameters are customizable –Type of branch predictor –Issue width –Etc. GPUs

8 Simulator – Memory Hierarchy Complete memory hierarchy Coherency: MOESI Flexible hierarchy: # of memory levels and memory structures in each level Each memory structure is fully customizable –#Sets –#Ways –Block size

9 Simulator – Interconnection Network Interconnection network: Any topology can be implemented Forwarding tables routing (any routing algorithm can be used) Each network element is fully customizable –Buffer size at switches –Link bandwidth

10 Outline Motivation Simulator Proposed Methodology Case Study Conclusions

11 Proposed Methodology Tries to motivate the students into processor architecture Realistic examples Increasing difficulty levels Shared use in several courses Develop basic skills for final projects, MS thesis or Ph.D thesis Based on a progressive interaction with Multi2Sim 4 learning phases with increasing difficulty due to the simulator’s complexity

12 Proposed Methodology 1 st phase: Simulation parameters modifications ( at labs) –Configure the system components –Launch simulations –Analyze the effects of the parameters on the system performance

13 Proposed Methodology 2 nd phase: Modify small pieces of code –Very small and bounded fragments of source code –Completely guided by the instructors –Modification of a provided baseline –Examples: Branch predictor, prefetch mechanisms,… –Final work of the course

14 Proposed Methodology 3 rd phase: Implementation complete functionalities –Consolidated simulator skills –Development of functionalities from scratch –Examples: Memory controller, Stream-buffers based prefetcher,… –Final project or MS thesis –Some works have been published in top level conferences 4 th phase: Complete autonomy –The students are in a privileged position to start a Ph.D.

15 Outline Motivation Simulator Proposed Methodology Case Study Conclusions

16 Case study The methodology has been implanted at the UPV in two courses Advanced Processor Architectures –Computer Science Degree and Master Degree Networks on-chip –Master Degree We have defined several learning stages with the simulator Baseline system modeling Execution of standard benchmark suites Prefetching mechanisms implementation

17 Case study Baseline system modeling

18 Case study Baseline system modeling Detailed explanation of the configuration for –Memory –Cores –Interconnection network Sample configuration files are used

19 Case study Benchmark Execution Parallel (Splash 2) Multiprogrammed mixes (Spec) Performance study (IPC, Execution Time, Network latency) varying L2 block size

20 Case study Prefetching mechanisms implementation Base simple prefetching mechanism provided –OBL (One Block Look-ahead) on L2 miss Modification to this mechanism –N-block sequential –N-block with regular stride

21 Case study Results This year 2 final projects have been performed in memory controller and prefetching Results from these projects are expected to be sent to first level international conferences These projects are expected to be evolved into MS thesis Results projection is based on the experiences from previous year, in which results from the projects were accepted in PACT and IPDPS conferences

22 Outline Motivation Simulator Proposed Methodology Case Study Conclusions

23 Conclusions We have reduced the gap between theoretical contents on Computer Architecture topics and real processors By using a well-established CMP-simulator in the international research community Methodology based on an increasing degree of difficulty First steps are very guided by instructors Students are encouraged to go ahead to more complex implementations Methodology + simulator = good platform for future works as the range of design choices is very wide

Conference title24 Thanks you for your attention