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Type of Talk: UTCS Colloquia/Architecture

Speaker/Affiliati

on: Daniel Jiménez/University of Texas, San Antonio

Date/Time: Wedne

sday, November 10, 2010, 3:30 pm

Location: ACES 2.302

Host: Ka

thryn McKinley

Talk Title: Reducing Wasted Speculation

Talk Abstr

act:
Modern microprocessors achieve high performance through aggressive

speculation. However, large amounts of energy and potential performance ar

e lost by speculating fruitlessly. The two most important speculation techn

iques are caches and speculative execution.

Caches hold a subset of th

e blocks from the high-latency main memory, speculating that quick access

to these blocks will benefit the program. Unfortunately, most blocks in th

e last-level cache will not be referenced again before they are removed fro

m the cache. These dead blocks waste time and energy as they reduce the eff

ective capacity of the cache.

Speculative execution mitigates pipeline
control hazards by predicting the outcome of branches, allowing subsequen

t instructions to be fetched and executed down the predicted path. Many ins

tructions will be wrongly executed before an incorrect prediction is discov

ered, again wasting time and energy.

This talk discusses novel techni

ques for reclaiming lost performance and energy through reducing speculatio

n wasted by caches and speculative execution. The talk will also discuss on

going projects and future research directions.

Speaker Bio:
Daniel A

. Jimenez is an Associate Professor in the Department of Computer Science a

t The University of Texas at San Antonio. He is currently on leave at the B

arcelona Supercomputing Center. His research focuses on microarchitecture a

nd low-level compiler optimizations. From 2002 through 2007, Daniel was an
Assistant Professor in the Department of Computer Science at Rutgers. In 2

005 Daniel took sabbatical leave at the Technical University of Catalonia (

UPC) in Barcelona, Catalonia, Spain. In 2008 he was promoted to Associate
Professor with tenure at Rutgers. Daniel earned his B.S. (1992) and M.S. (

1994) in Computer Science at The University of Texas at San Antonio and his
Ph.D. (2002) in Computer Sciences at The University of Texas at Austin. He
is an NSF CAREER award recipient, an ACM Senior Member, and General Chai

r of the 2011 HPCA conference.