Asim/AWB Training Mohit Gambhir Intel Massachusetts Content: Joel Emer, Michael Pellauer, Chris Weaver

Agenda  AWB Overview  Modular Software Design  AWB Abstractions & Terminology  AWB Tools  Configuration File Formats  Asimcore (libasim) Overview

AWB  Architects Workbench  Originally written to create software performance models  Core Principle: Modularity  AWB facilitates the modular plug-n-play style construction of software and hybrid software/hardware projects

AWB (contd.)  A suite of tools to support rapid modular construction and analysis of performance model  GUI and command-line based  Publically released under the GPL (models are not)  Across Multiple:  Code bases:  Different repositories, or even types of repositories  Model configurations:  Alternative modules, knobs, levels of accuracy  ISA variations  Benchmark suites  Results from different runs, etc.

Why Modularity  Speed of model development  Shared components between products  Reuse across generations  Encourages isomorphism to design  Improved fidelity  Facilitates speed/fidelity trade-offs  Architectural experimentation  Factorial development and evaluations  Sharing

AWB Abstractions & Terminology  Packages (codebases) are stored in repositories  Packages can be grouped into related bundles  Users check out bundles into local workspaces  The set of packages in a workspace is viewed a Union Dir  Bundle packages contain modules (modular source code)  Modules are arranged into models (configurations)  Each workspace can contain multiple model build directories  Each build directory can contain multiple benchmark runs

AWB Abstractions and Terminology  Workspace  Configure (a model)  Repository  Bundle  Package  Model  Module  Uniondir Search Path

Workspace  Directory where one works on the AWB based project  awb commands that need a workspace context in which to operate search up the directory tree until they find the root of a workspace.  contain a stylized directory structure

Workspace

Configure  Collect a set of source files together that can be built into a specific design or model  The specific set of modules (and hence source code) that comprise a specific model are specified in an.apm file.  Since a model is created from a pool of modules, the build paradigm adds a new step to “configure” a model source tree from a pool of modules.  Thus given an.apm file, the configure process involves placing copies of the designated source files (via symbolic links) and some automatically created glue files into a model-specific subtree in the build area of the workspace.

Repository  A repository is a source code repository using one of the supported source code management systems.  Supported versioning systems - CVS, SVN, Bitkeeper and git  Repository specification  [/ ]  The set of available repository names are specified in a.pack file.  /etc/respositories/.pack  ~/.asim/respositories/.pack

Bundle  Collection of repositories (with optional versions) – used to checkout a group of packages together.  Bundle specification  [/ ]  Bundles are specified in bundlefiles  /etc/asim/bundles.d/  ~/.asim/bundles.d/  files files

Package

 Portion of repository that is checked out in the workspace  the configure/Makefile.in/Makefile files are optional and do not build a user's model, but simply the tools that might exist in the package  Globally installed packages that can be shared by all users  /share/asim/ /  Private packages:  /src/

Model  An AWB model is a hierarchical representation of a design, where each node of the hierarchy is a module  Each workspace may have multiple models configured/built each constructed plug-n-play style out of the pool of modules available in all packages in a workspace  Represented in.apm file  Typically found in config/pm directory inside a package  Can be edited by apm-edit  In the AWB editor GUI, models are marked with an icon which looks like a double cog

Module  Modules represent the unit of “swapability” in source code  If two modules provide the same awb type then this is an assertion that they can be swapped for one another and that the result will be a coherent model that will successfully build  Each module is specified in an.awb file which specifies  ‘awb-type’of the module,  Awb-types of the children modules that it 'requires'  Source files that implement the module.

Uniondir Search Path  awb supports a union mount-like directory structure that overlays the files from a set of packages.  This set of packages is specified as a uniondir search path  File references resolved through search of all package directories in the search path  Packages added to search path at checkout awb-resolver config/pm/simcore/model.apm /home/mgambhir/asim/src/asim- simcore/config/pm/simcore/model.pm

AWB Operation Example Repositories Workspace

AWB Tools  awb-shell  awb  apm-edit

Awb-shell  This is a program that provides a command line interface to manipulate various ASIM objects.  Has default values for these Asim objects  Can set reset default values through set command  help command displays all possible commands   awb-shell help quickstart

Awb-shell % awb-shell awb> set model pm/Arana/arana_aint_dev.apm awb> clean model awb> configure model awb> build model awb> run model bm/Micro/maxipc.cfg awb> quit % awb-shell awb> set model pm/Arana/arana_aint_dev.apm awb> clean model awb> configure model awb> build model awb> run model bm/Micro/maxipc.cfg awb> quit % awb-shell --package=arana commit package % awb-shell help % awb-shell help code

Awb-shell  Primer for most commonly used awb-shell wrapped svn commands  awb-shell checkout package  awb-shell update package  awb-shell commit package  Make sure that environment variable EDITOR is set to your favorite EDITOR  setenv EDITOR vi  awb-shell checkout package /  To checkout a package branch  awb-shell checkout package /  To checkout a particular revision of a package

Awb-shell  Bundle commands  awb-shell new bundle [/ ]  By default takes a snapshot of packages in the current workspace  By default adds the file into ~/.asim/bundles/release  Use --head to specify the head version  Use --install to publicly install in /p/asim  Requires asimadm permissions  awb-shell checkout bundle [/ ]  awb-shell update bundle [/ ]  awb-shell show bundle [/ ]

Awb  cd into your workspace  Type: “awb”

Awb

Lets Select an ape softsdv model

Awb Nuke

Awb Configure

Awb Build

Apm-edit

Configuration File formats  Workspace configuration: awb.config   Model description:.apm file   Module description:.awb file   Benchmark description:.cfg file   Multiple benchmark description:.cfx file 

Asimcore (libasim) overview  Clocking  Ports  Stats

Clocking  Cycle accurate models:  Hierarchical and explicit time control void ASIM_CPU_CLASS::Clock (UINT64 cycle) { efmmbx.Clock(cycle); mbx.Clock(cycle); qbx.Clock(cycle); ibx.Clock(cycle); … }  Clock Server bool ASIM_RBOX_CLASS::InitModule () { ostringstream os; os << "SYSINT_CLOCK_DOMAIN_" << myUniqueRboxId; RegisterClock(os.str()); }  Clock techniques can be combined

Clocking  Creating Clock domains  void newClockDomain (string name, float freq, INT32 threadId = -1)  void newClockDomain (string name, list freqs, INT32 threadId = -1) List of valid frequencies

Clocking  Set Domain Frequency void setDomainFrequency (string domainName, float freq)  Register Clock void RegisterClock (string domainName, UINT32 skew = 0, INT32 threadId = -1, bool referenceDomain = false) void RegisterClock (string domainName, CLOCK_CALLBACK_INTERFACE cb, UINT32 skew = 0, INT32 threadId = -1, bool referenceDomain = false) void RegisterClock (string domainName, CLOCK_CALLBACK_INTERFACE cb, CLK_EDGE ed, UINT32 skew = 0, INT32 threadId = -1, bool referenceDomain = false)

Clocking template CLOCK_CALLBACK_INTERFACE newCallback (T *obj, void (T::*meth)(UINT64))  Traditionally all the module work happen in one method: void Clock(UINT64 cycle)  Callbacks enable:  Having more that one clock method in a module  Clocking a module at different frequencies

Clocking bool ASIM_CBOX_CLASS::InitModule () { … ostringstream os; os.str(""); os << "RING_CLOCK_DOMAIN_" << myChipNum; RegisterClock(os.str()); os.str(""); os << "CBOX_CLOCK_DOMAIN_" << myChipNum; RegisterClock(os.str(), newCallback(this, &ASIM_CBOX_CLASS::ClockCBOX)); … } void ASIM_CBOX_CLASS::ClockCBOX (const UINT64 cycle) { // Clocked at CBOX frequency …} void ASIM_CBOX_CLASS::Clock (const UINT64 cycle) { // Clocked at Ring frequency …}

Ports  In an Asim model, time only passes when messages flow through ports  Activity within each module is instantaneously fast  Each port defines a latency and a bandwidth  BW: Number of abstract objects that can enter/exit in a cycle  LAT: Number of cycles that objects travel through port  Sender defines BW and receiver defines LAT  Benefits:  LAT and BW are often useful knobs for architectural exploration  Separates functionality from timing  Encourages reuse  Can ease burden of coding “NetworkInUse” 2

Ports  Connect modules  Read port and write port make a connection  BW set by writer  Latency set be reader  What gets passed through ports?  Pointers to objects  allows for generic interfaces between modules  does make it easier to “cheat” by accessing info that shouldn’t be available to certain modules  Bools & integers

Ports WritePort var1_WPort; var1_WPort.Init("Unique_String"); var1_WPort.SetBandwidth(bandwidth); ReadPort var1_RPort; var1_RPort.Init("Unique_String"); var1_RPort.SetLatency(latency);

Ports // Write data into the port in cycle C CPU_INST inst; var1_WPort.Write(inst1, cycle); // Read data in cycle C + latency CPU_INST inst2; var2_RPort.Read(inst2, cycle);

Ports WritePort var1_WPort; var1_WPort.Init("Unique_String"); var1_WPort.Config(bandwidth); ReadPort var2_RPort var2_RPort.Init("Unique_String"); var2_RPort.Config(latency); ReadPort var3_RPort var3_RPort.Init("Unique_String"); var3_RPort.Config(latency + 1); ReadPort var4_RPort var4_RPort.Init("Unique_String"); var4_RPort.Config(latency +2);

Ports  Other Kinds of Ports  Stall Ports  Enable reader to stall the port to disable write from writing  Rate Matcher Ports  To connect modules in different frequency domains  Skid Ports  Allow lazy reading of data

Stats  Stat Types  Scalar  Stats that comprise of one value collected over the entire simulation run.  For eg. DCacheMisses  Multidimensional (Histograms)  These stats show the number of times particular clusters of events occur.  For eg, the number of times N instructions were issued in a cycle where N for an 8 way processor varies from 0 to 8.  Per Instructions Stats  Global  Per instruction type  Per instruction

Stats  Declare the stats data member of a class as a UINT64, Double, UINT64* or a Double*  UINT64 dstreamFull;  UINT64 instsRetired[CPU_THREADS];  Register the stats variable with StatsRegistry class  RegisterState(dstreamFull, "PremafDstreamFull", "Number of dstream full events");  RegisterState(instsRetired, CPU_THREADS, "RetiredInstructions", "Retired Instructions");  Accumulate Stats  dstreamFull++;  instRetired[tpu]++;

Stats  Histograms Stats  Declaration  HISTOGRAM_TEMPLATE instrIssuedPerCycle  Initilization  HISTOGRAM_TEMPLATE (UINT32 num_rows, UINT32 num_cols = 1, UINT32 row_size = 1, BOOL row_flex_cap = FALSE, UINT32 col_size = 1, BOOL col_flex_cap = FALSE )  Register  RegisterState(&instrIssuedPerCycle, "instrIssuedPerCycle", "Number of instructions issued from the IQ per cycle");  Accumulate Stats  AddEvent(UINT32 row_val, UINT32 col_val = 0, UINT64 value = 1)  AddEventWideBins(UINT32 row_val, UINT32 col_val = 0, UINT64 value = 1)

Stats  Command line switches  -sc Emit stats file every cycles  -sn Emit stats file every nanoseconds  -si Emit stats file every instructions  -sm Emit stats file every macro instructions  -rsc Reset stats on cycle  -rsi Reset stats on instruction  -rsm Reset stats on macro instruction  -rsn Reset stats on nanosecond  Adding a p after the previous flags (for instance -rscp) will reset stats periodically after events