1. Progetto MAIS - WP5 esplorazione di architetture alternative Resoconto delle attività svolte Andrea Pagni STMicroelectronics Advanced System Architectures Group Milano, 17-18 Novembre 2004

2. Resoconto WP5 2 Topics Part 1: VLIW-SIM Overview. Part 2: VLIW-SIM Performance. Part 3: VLIW-SIM Library. Part 4: Next Steps.

3. Part 1: VLIW-SIM Overview

4. Resoconto WP5 4 Part 1: VLIW-SIM Overview Simulation Approach (1-7). Modeled Target Architectures. Supported platforms. Simulation functionalities.

5. Resoconto WP5 5 Simulation Approach 1/7 Overview s Interpretative Simulation Approach s Simulation Technology based on a set of re-usable sub-blocks s Pipeline modeling s Instruction execution s Memory modeling s Register file management s I/O simulation s Efficient Host Resources Allocation s Target Architecture Description capability (IS, TAD) s Challenging compromise between Speed and Accuracy

6. Resoconto WP5 6 During simulation, the pipeline is represented as a 3-dimensional space (phase, operation, time): operation means the instructions position in the bundle, phase is the pipelines phase and time is the given time stamp. Simulation Approach 2/7 pipeline modelling

7. Resoconto WP5 7 Simulation Approach 3/7 Pipeline modelling s The pipeline status is modelled via a two-dimension array: s The first index is the pipeline phase and the second one is the position of a certain instruction in the fetch-packet. s The simulation process is based on two arrays like the one described above, to represent the current and the following pipeline statuses. s At each machine cycle the pipeline status is processed: actions depending on which instructions are at that phase and then the instructions are moved to the next pipeline phase.

8. Resoconto WP5 8 At each machine cycle the pipeline status is processed Simulation Approach 4/7 pipeline status update

9. Resoconto WP5 9 Instructions execution is simulated through an Instruction Table which contains the instruction-routine address and the instruction latency value. Simulation Approach 5/7 Instruction execution

10. Resoconto WP5 10 s The simulation environment is based on the progressive pipeline status updating taking into account the data coherence in memory locations and in the register file. s To support data coherence two Register files have been used: one for the current Register File status and the other one for the following. s Each time an instruction is executed its operands are loaded from the current register file and results are stored in the following. s This allows sequential simulation of parallel instruction execution. Simulation Approach 6/7 register file status update

11. Resoconto WP5 11 Simulation Approach 7/7 I/O simulation s I/O Target Architecture specific features separated from Simulation kernel s The SYSCALL pseudo- instruction manages the interface between internal I/O instruction (processor side) and File System I/O calls (OS side). s SYSCALL handle also the general Exception Handling s This mechanism is transparent to other simulator modules: Performance and data flow are not influenced if I/O operation are not present. Details

12. Resoconto WP5 12 Modeled Target Architectures s Multi-cluster Architecture s 4-issue VLIW core s I/D-cache memories s 6-stages pipeline s RISC-like Instruction Set s 64 32-bit General registers, 8 1-bit special registers ST210TI C62x s 8-issue VLIW core s Optional I-cache memory s 11-stages pipeline s RISC-like Instruction Set s 32 32-bit General registers TI C64x s 8-issue VLIW core s I/D cache memories s 11-stages pipeline s RISC/SIMD Instruction Set s 64 32-bit General registers

13. Resoconto WP5 13 Windows OS (Visual C++): text mode: project file in vliw_sim/vliw_sim graphical mode: project file in vliw_sim/gui/gui Windows OS (Cygwin, gcc): text mode: makefile in vliw_sim/vliw_sim graphical mode (with XWindows on Cygwin) Linux OS (RedHat, gcc): text mode: makefile in vliw_sim/vliw_sim graphical mode: makefile in vliw_sim/gui/gui Sun OS (Solaris, gcc) text mode: makefile in vliw_sim/vliw_sim graphical mode: makefile in vliw_sim/gui/gui vliw_sim bin_loader cache gui/gui instruction_set io_interf memory pipeline profdebug registers vliw_sim vliw_sim_dll Supported Platforms

14. Resoconto WP5 14 Simulation functionalities Debug Support Step-by-step execution Breakpoint Register & Memory access Pipeline Visibility (instruction & addresses) Profiling Application Code region Profile Statistics extraction for profiled code Simulator Dynamic Library Simulation API SoC simulation facilities Exception Handling simulation Efficient I/O interface simulation

15. Part 2: VLIW-SIM Performance

16. Resoconto WP5 16 Part 2: VLIW-SIM Performance Tested Applications. SW apps on ST210. SW apps on TI C62x. SW apps on TI C64x. SW apps on ST210 (1-2).

17. Resoconto WP5 17 Tested Applications ST210. MPEG-2 Intra Video Encoder (0.2s, 5 frames, 15 Mbit/s). MPEG-1 Layer 2 Audio Encoder (1s, 32KHz 256 kbit/s). MPEG-2 M=3 MP@ML Video Decoder (1s, 25 frames/s, 15 Mbit/s). MPEG-4 QCIF SP@L3 Video Decoder (1s, 25 frames/s, 512 kbit/s). MPEG-4 QCIF SP@L3 Video Encoder (27 frames, 64 kbit/s, QP=12). H.263+ QCIF Video Encoder (10 frames, No rate-control). G.723.1 Audio Enc-Dec (20 frames, 8 kHz, 5.3 kbit/s). Automatic Speech Recognition (HMM, 5 words, 8 MEL, 50 active words). TI C62x & C64x. H.263+ Video Enc QCIF (5 frames, No rate-control) G.726 Audio Enc-Dec (10 frames, 8kHz, 32 kbit/s)

18. Resoconto WP5 18 SW apps on TI-C62x Operation = one syllable (elementary 32-bit RISC instruction)

19. Resoconto WP5 19 SW apps on TI-C64x Bundle = more syllables (max 8 for TI C6xx, max 4 for ST210) per clock cycle

20. Resoconto WP5 20 SW apps on ST210 1/3 HP ISS configured with: ignore_non_cacheable_areas TRUE profile_gprof_on FALSE

21. Resoconto WP5 21 SW apps on ST210 2/3 HP ISS configured with: ignore_non_cacheable_areas TRUE profile_gprof_on FALSE

22. Resoconto WP5 22 SW apps on ST210 3/3 MOPS = Millions Of Operations Per Sec

23. Part 3: VLIW-SIM Library

24. Resoconto WP5 24 Part 3: VLIW-SIM Library VLIW-SIM Library (1-2).

25. Resoconto WP5 25 VLIW-SIM Library 1/2 The VLIW-SIM can be configured as both stand-alone and dynamic library (DLL). extremely useful to interface VLIW-SIM with other applications (system on chip simulation environment, Graphical User Interface, etc.). The simulator-exported functionalities can be divided into two subgroups: Command Functionalities: used to control the simulation (Run, Stop, Insert/remove breakpoint, Continue, Step, etc.) Status Functionality: used to retrieve the simulator internal status and resource allocation (pipeline status and size, register file content and size, etc.)

26. Resoconto WP5 26 VLIW-SIM Library 2/2 The simulator DLL exports the following functionalities: Control Functions Load Init Step / Step N / Stall Run Restart Debug Support View simulator status ( Pipeline, Register File, Memory ) Breakpoint Utility functions Code profiling Simulated Program Arguments

27. Part 4: Next Steps

28. Resoconto WP5 28 Part 4: Next Steps Where we are. VLIW-SIM Developments.

29. Resoconto WP5 29 Released version 2.0 and 3.0 of VLIW-SIM. A lot of SW engineering work to improve: Modularity Readibility (doxygen generated documentation) Simulation speed Architectural accuracy: ST210: IPU, DPU, Interrupt Controller, Core Memory Controller, I-cache, D-cache TI C6x: I-cache and D-cache for CPU style, program memory and data memory for DSP style Accurate and not invasive flat profiling (GNU format compatible) Architectural flexible re-configurability Host platform independency Future integration into high level system tools Where we are

30. Resoconto WP5 30 ST220 accurate modelling Integration inside MaxSim system simulation tools and related experiments VLIW-SIM developments

31. Fine Domande?