Using Kilim's isolation types for multicore efficiency

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Introduction to multi-core hardware semantics Two ‘obvious’ but incorrect statements: 1. If a program with two threads runs on a single-core processor then it will run unchanged on a two-core processor. UNIVERSITYOF CAMBRIDGE 2. (After correcting problems in 1.) a two-thread program will run faster on a two-core processor than it runs on a single-core processor. Brief answer: need to think of multi-core processors as distibuted systems not merely as concurrent systems. Using Kilim’s isolation types for multicore efficiency 10 FoVeOOS’2011
Multi-core and sequential consistency On a single-core (implementing tasking using interrupts) the instructions in each thread are interleaved. volatile int x=0,y=0; thread1: { x=1; print "y=",y; } thread2: { y=1; print "x=",x; } For most executions this program prints x=0, y=1 or x=1, y=0; • relatively rarely it prints x=1, y=1; • but it never prints x=0, y=0. UNIVERSITYOF CAMBRIDGE But on multi-core x=0, y=0 can happen! Not all executions interleave instructions from the two threads (they do on a single-core processor with interrupt-driven scheduling). Failure of sequential consistency. Using Kilim’s isolation types for multicore efficiency 11 FoVeOOS’2011
Page 1 and 2: UNIVERSITYOF CAMBRIDGE Using Kilim
Page 3 and 4: The big picture • Traditional obj
Page 5 and 6: Why does multi-core affect things?
Page 7 and 8: • an example • modern hardware
Page 9: • an example • modern hardware
Page 13 and 14: Multi-core hardware semantics (2) I
Page 15 and 16: Multi-core-chip memory models Today
Page 17 and 18: How should we react? Shared memory
Page 19 and 20: Caches are multiple-reader/single-w
Page 23 and 24: Type Systems - weakness UNIVERSITYO
Page 25 and 26: Classical and Linear Type Systems (
Page 27 and 28: Substructural type systems (WEAKEN)
Page 29 and 30: An algebra of capabilities UNIVERSI
Page 31 and 32: From algebra to algorithm UNIVERSIT
Page 35 and 36: Kilim qualifiers UNIVERSITYOF CAMBR
Page 37 and 38: Core Kilim syntax FuncDcl ::= free
Page 39 and 40: Kilim isolation type checking Many
Page 41 and 42: One neat point UNIVERSITYOF CAMBRID
Page 43 and 44: What I didn’t say about Kilim UNI
Page 45: Conclusions • multi-core works be

Using Kilim's isolation types for multicore efficiency

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