(1) SIMICS Overview

(2) SIMICS – A Full System Simulator Models disks, runs unaltered OSs etc. Accuracy is high (e.g., pollution effects factored in) Simulates all benchmarks Requires in-depth OS knowledge –paging, scheduling, even sendmail! Bottom line : System runs unmodified instructions and code

(3) SIMICS – Features Snapshot Multi-processor full system simulator Processors are simulated at the instruction-set level –Support for various ISAs, e.g., SPARC, x86, PPC, ARM Extensible –Mix and match architectures with operating systems –Facilitates gathering of timing information –Extensible instructions "bare bones" simulation possible

(4) Applications Processor Design MP architecture OS Development and Emulation Debugging Memory hierarchy design

(5) SIMICS Architecture

(6) Breaking Down SIMICS SIMICS Central High-level architecture specification Features –New device modules plug in to Simics framework – Simics API provides functions, interfaces, etc for user extensions –Global time can be paused to inspect state –Access memory traffic or set breakpoints anywhere, –Checkpoint simulations –Timestamp user inputs

(7) SIMICS Central Heterogeneous nodes can be connected into a network using Simics Central –Synchronizes virtual time –Distributes simulated traffic between nodes Imposes a minimum latency on all messages Network simulation speed is limited by the slowest process Currently supports Ethernet networks

(8) Memory and I/O Users can extend a simulated memory space by adding a timing model (such as Ruby) Simple cache models can be added to the base simulator Device models supported extensively –Keyboard/mouse controller, DMA, Interrupt controller, floppy controller, Graphics cards, etc. –Users can write new device models

(9) Event Handling Simics can mix event-driven and time- driven components –step queue and time queue step queue  pc steps time queue resolution  clock cycle

(10) SIMICS Slowdown Best case 10X - 100X –Limited statistics Cache 1000X X –in-order processor Processor 10000X - 1million –cycle-accurate Implication  choose simulations wisely

(11) References Micro 35 Tutorial: currentsemester/handouts/simics_tuto rial.pdf currentsemester/handouts/simics_tuto rial.pdf er01/magnusson pdf