Introduction to the BOINC software David P. Anderson Space Sciences Laboratory University of California, Berkeley

Outline Abstractions The BOINC server software The BOINC client software and runtime system

Design goals A few applications, lots of jobs High performance – millions of jobs per day Scalability Fault tolerance

Abstractions Platform App version – a collection of files, one of which is an executable main program – associated with a platform App – a set of app versions that all perform roughly the same computation – may have versions for different platforms – may have different versions for one platform (GPU, non-GPU)

Abstractions Workunit (job) – a collection of input files – associated with an app (not an app version!) – attributes resource estimates and bounds latency bound Result (job instance) – a collection of output files – associated with a workunit

Anatomy of a BOINC project MySQL database project root/ bin/ cgi-bin/ download/ 00/.. 3ff/ html/ log_*/ templates/ upload/ 00/.. 3ff/ servers daemons and periodic tasks clients

Work generator MySQL database project root/ bin/ cgi-bin/ download/ 00/.. 3ff/ html/ log_*/ templates/ upload/ 00/.. 3ff/ work generator Creates input files Creates workunits One per app Flow control – disk space – DB size

Specifying a job Workunit template – XML document describing input files (logical, physical names) job attributes Result template – XML document describing output files create_work() – specifies templates, app, input files

Validator Check result validity Compare replicas May be app-specific MySQL database project root/ bin/ cgi-bin/ download/ 00/.. 3ff/ html/ log_*/ templates/ upload/ 00/.. 3ff/ validator

Validation Clients may – return bad results – exaggerated claimed credit Strategies – app-specific consistency checking – replication fuzzy comparison homogeneous redundancy – adaptive replication

Assimilator Processes completed results App-specific MySQL database project root/ bin/ cgi-bin/ download/ 00/.. 3ff/ html/ log_*/ templates/ upload/ 00/.. 3ff/ assimilator

Summary Create app, app versions for different platforms Develop work generator Develop validator Develop assimilator Isn’t there a simpler way?

Single-job submission Assemble your input files and executable, then boinc_submit --input foo --output blah program How this works: – uses “wrapper” app – executable is part of workunit – templates are created automatically What it doesn’t do: – multi-platform – validation

Job dispatch MySQL database project root/ bin/ cgi-bin/ download/ 00/.. 3ff/ html/ log_*/ templates/ upload/ 00/.. 3ff/ transitioner feeder scheduler (CGI or FastCGI) share-memory job cache clients

File transfer project root/ bin/ cgi-bin/ download/ 00/.. 3ff/ html/ log_*/ templates/ upload/ 00/.. 3ff/ Apache file upload handler clients

Janitorial daemons MySQL database project root/ bin/ cgi-bin/ download/ 00/.. 3ff/ html/ log_*/ templates/ upload/ 00/.. 3ff/ file deleter DB purger

Ways to deploy a BOINC server Linux server Server VM for VMWare Server VM for Amazon EC2

The BOINC runtime system Directory structure: BOINC/ projects/ lhcathome/ physical_name0 physical_name1 setiathome/ slots/ 0/ logical_name0 (link file) logical_name1 1/ BOINC client application share-memory message-passing BOINC runtime fraction done CPU time suspend resume quit

Basic API boinc_init() – creates a thread that handles messages boinc_finish() – creates a “finish file” boinc_resolve_filename() – maps logical to physical file names

Checkpointing boinc_time_to_checkpoint() – call at points where you can checkpoint boinc_checkpoint_done() – call when you’re finished checkpointing

Compound applications Examples: – coordinator program runs several worker programs in sequence – “switcher” program probes CPU architecture, selects which executable to run Variants of boinc_init() let you specify which app is main program, and how messages are handled Each message type must be handled by 1 process

Long-running applications Trickle-up messages Trickle-down messages Intermediate file transfers

Legacy applications The BOINC wrapper – takes XML “job file” – handles all messages

GPU and multithread apps Server – you supply a function that takes an app version and a host, and returns resource usage and estimated FLOPS – the BOINC scheduler chooses the best version Client – senses and reports coprocessors (e.g. NVIDIA GPUs) – coprocessor-aware scheduling and work fetch