MilkyWay@Home andVolunteer Computing

at RPI

Travis Desell

RCOS, April 23, 2010

MilkyWay@Home & Open Source Software

•Milky Way Modeling Application• Multi-Platform Development: ATI,

CUDA, OpenCL, Windows, OS X, Linux

•Generic Optimization Code (in the works)

•BOINC - Berkeley Open Infrastructure for Network Computing

MilkyWay@Home Statistics

•~20,000 active users•~30,000 active hosts

•~1.6 petaflops:• most powerful BOINC project• 3rd most powerful computing system

(behind Folding@Home and the fastest supercomputer)

• most of this from GPU computing

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MilkyWay@Home GPU Application

First GPU implementation was user-contributed

Compared to 3.0Ghz AMD Phenom(tm) II X4 940:• ATI HD5870 GPU - 109x speedup• NVidia GeForce GTX 285 GPU - 17x speedup

Requires double-precision calculations:• NVidia GPUs have less double precision real estate• Application would be 6.2x faster on the ATI GPU, 7.8x

faster on the NVidia GPU using single-precision math

Travis Desell, Anthony Waters, Malik Magdon-Ismail, Boleslaw Szymanski, Carlos Varela, Matthew Newby, Heidi Newberg, Andreas Przystawik and Dave Anderson. Accelerating the MilkyWay@Home volunteer computing project with GPUs. In the 8th International Conference on Parallel Processing and Applied Mathematics (PPAM 2009) , Wroclaw, Poland, September 2009.

The Sagittarius Dwarf Tidal Stream

Image (above): [Ibata et al. 1997, AJ]

Image (below): David Martinez-Delgado (MPIA) & Gabriel Perez (IAC)

• The Sagittarius Dwarf Galaxy is merging with the Milky Way • The dwarf is being tidally disrupted by the Milky Way, creating long “tails.”

• Provide information on matter distribution in Milky Way• Provide constraints on Galactic Halo

Mapping the Tidal Stream will:

Image: sdss.org

• 230+ million objects• 8,400 square degrees in the sky• Large percentage of north galactic cap• Very little data in galactic plane (too much dust)• Several hundred thousand stars

SLOAN Digital Sky Survey

The Milky WayHaloBulgeThin DiskThick Disk

~30 kiloparsecs (100,000 light-years)

Sun

Sagittarius Dwarf Galaxy

Tidal Stream

Data Wedge

Image:Matthew Newby

Sagittarius Stream Model

• Assume stream is a cylinder• Radial drop-off given by a Gaussian Distribution

• 2 background parameters (new model has 4):r0, q• 6 parameters per stream:ε, μ, r, θ, φ, σ

• A single stream with the old model has an 8 dimensional search space• Often fit multiple streams for search spaces with more than 20 dimensions!

Background distribution:

BOINC

Active development mailing lists:• boinc_dev@ssl.berkeley.edu• boinc_projects@ssl.berkeley.edu• boinc_alpha@ssl.berkeley.edu

Client Development:• Supporting different architectures (GPUs)• Awarding fair “credit” for work done

Server Development:• Scheduling• Validation & Verification

DNA@Home

• Find protein binding sites using Gibbs sampling

• Use random walks (Markov chains) which result in sites distributed according to their actual probability of being the correct binding site

• Initial sequences:• Mycobacterium tuberculosis• Yersinia pestis (cause of the

Bubonic plague)

Participate

• http://milkyway.cs.rpi.edu : astro@cs.rpi.edu

• http://dnahome.cs.rpi.edu : dna@cs.rpi.edu

• http://boinc.berkeley.edu