Il sistema di calcolo ad alte prestazioni del CINECA: evoluzione di ...

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Thread A thread is defined as an independent stream of instructions that can be scheduled to run as such by the operating system. Threads use and exist within the process resources - are able to be scheduled by the operating system - run as independent entities - they duplicate only the bare essential resources that enable them to exist as executable code. This independent flow of control is accomplished because a thread maintains its own: - Stack pointer - Registers - Scheduling properties (such as policy or priority) - Set of pending and blocked signals - Thread specific data. Threads may share the process resources with other threads that act equally independently (and dependently) Reading and writing to the same memory locations is possible, and therefore requires explicit synchronization by the programmer. Thread die if the parent process dies Thread Iis "lightweight" because most of the overhead has already been accomplished through the creation of its process. www.cineca.it 6
MPI Execution Model - Single Program Multiple Data - A copy of the code is executed by each process - the execution flow is differnt dipending from the context (process id, local data, etc) www.cineca.it 7
Page 1 and 2: CINECA Casalecchio di Reno (BO) www
Page 3 and 4: Parallel Architectures P P M P P SM
Page 5: Process A process is created by the
Page 9 and 10: Processors: trends Aggregate Number
Page 11 and 12: Hybrid Model Multi-node SMP (Symmet
Page 13 and 14: www.cineca.it 13
Page 15 and 16: Domain decomposition /1 The hybrid
Page 17 and 18: MPI plus OpenMP Pro: Better use o
Page 19 and 20: Hybrid pseudo code call MPI_INIT (i
Page 21 and 22: Mixed paradigm www.cineca.it 21
Page 23 and 24: MPI_THREAD_SINGLE (master only) !$O
Page 25 and 26: MPI_THREAD_FUNNELED - calls outside
Page 27 and 28: MPI_THREAD_SERIALIZED • Outside t
Page 29 and 30: HPC Evolution From Herb Sutter Moor
Page 31 and 32: Real HPC Crisis is with Software A
Page 33: Some Current Unmet Needs Performanc

Il sistema di calcolo ad alte prestazioni del CINECA: evoluzione di ...

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