Shared Last-Level TLBs for Chip

MultiprocessorsAbhishek Bhattacharjee

Daniel Lustig Margaret Martonosi

HPCA 2011

Presented by: Apostolos KotsiolisCS 7123 – Research Seminar

Translation Lookaside Buffer

ContributionSLL TLB design explored for the

first timeAnalyze SLL TLB benefits for

parallel programsAnalyze multi-programmed

fashion workloads consisting of sequential applications

Previous and Related workPrivate Multilevel TLB Hierarchies

◦Intel i7, AMD K7-K8-K10, SPARC64-III◦No Sharing between cores◦Waste of resources

Inter-Core Cooperative Prefetching◦Two types of predictable misses:◦Inter-Core Shared (ICS)

Leader-Follower Prefetching◦Inter-Core Predictable Stride (ICPS)

Distance-Based Cross-Core Prefetching

Shared Last-Level TLBsExploit inter-core sharing in

parallel programsFlexible regarding where entries

can be placedBoth parallel and sequential

workloads are benefitedGreater Hit rateCPU Performance boosted

Shared Last-Level TLBs

Shared Last-Level TLBs with simple Stride Prefetching

Methodology

◦Parallel applications

◦Different Sequential application on each core

Two distinct evaluation sets

MethodologyBenchmarks

SLL TLBs: Parallel Workload ResultsSLL TLBs versus Private L2 TLBs

SLL TLBs: Parallel Workload ResultsSLL TLBs versus ICC Prefetching

SLL TLBs: Parallel Workload ResultsSLL TLBs versus ICC Prefetching

SLL TLBs: Parallel Workload Results

SLL TLBs with Simple Stride Prefetching

SLL TLBs: Parallel Workload ResultsSLL TLBs at Higher Core Counts

SLL TLBs: Parallel Workload ResultsPerformance Analysis

SLL TLBs: Multiprogrammed Workload ResultsMultiprogrammed Workloads with

One Application Pinned per Core

SLL TLBs: Multiprogrammed Workload ResultsPerformance Analysis

Conclusion-Benefits:On Parallel Workloads:

◦Elimination of 7-79% of L1 TLBs misses exploiting parallel program inter-core sharing

◦Outperform conventional per-core private L2 TLBs by average of 27%

◦Improve CPI up to 0.25On multiprogrammed sequential

workloads:◦Improve over private L2 TLBs by

average of 21%◦Improve CPI up to 0.4

Thank You!Questions?

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