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Programming Models for Multithreaded Architectures: The EARTH Threaded-C Experience

Programming Models for Multithreaded Architectures: The EARTH Threaded-C Experience. EARTH-MANNA Testbed. Local Memory. Local Memory. EU. EU. SU. SU. PE. PE. NETWORK. Features of Threaded Programming. Thread partition Thread length vs useful parallelism Where to “cut”?

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Programming Models for Multithreaded Architectures: The EARTH Threaded-C Experience

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  1. Programming Models forMultithreaded Architectures:The EARTH Threaded-C Experience \course\eleg652-03F\Topic5b-652.ppt

  2. EARTH-MANNA Testbed Local Memory Local Memory EU EU SU SU PE PE NETWORK \course\eleg652-03F\Topic5b-652.ppt

  3. Features of Threaded Programming • Thread partition • Thread length vs useful parallelism • Where to “cut”? • Split-phase synchronization and communication • Parallel threaded function invocation • Dynamic load balancing Latency tolerance and management \course\eleg652-03F\Topic5b-652.ppt

  4. cluster cluster cluster cluster cluster cluster cluster Crossbar- Hierarchies cluster cluster cluster cluster cluster cluster cluster cluster cluster Node CP CP i860XP i860XP 8 Network Interface I/O 8 32 Mbyte Memory The EARTH-MANNA Multiprocessor Testbed Cluster Node Node Node Node Node Crossbar 4 \course\eleg652-03F\Topic5b-652.ppt

  5. i860XP (EU) i860XP (SU) I/O Buf & Ctrl Arbiter 400 MB/s 50 MB/s Link Control MANNA Architecture Model LBE Memory (32MB) 50 MB/s \course\eleg652-03F\Topic5b-652.ppt

  6. Main Features of EARTH Multiprocessor • Fast thread context switching • Efficient parallel function invocation • Good support of fine-grain dynamic load balancing • Separate SU to hide thread sync/scheduling overhead and support of split-phase transaction Using off-the shell microprocessors \course\eleg652-03F\Topic5b-652.ppt

  7. Table 1. EARTH Instruction Set • Basic instructions: Arithmetic, Logic and Branching typical RISC instructions, e.g., those from the i860 • Thread Switching FETCH_NEXT • Synchronization SPAWN fp, ip SYNC fp, ss_off INIT_SYNC ss_off, sync_cnt, reset_cnt, ip INCR_SYNC fp, ss_off, value \course\eleg652-03F\Topic5b-652.ppt

  8. Con’d Table 1. EARTH Instruction Set • Data Transfer & Synchronization DATA_SPAWN value, dest_addr, fp, ip DATA_SYNC value, dest_addr, fp, ss_off BLOCKDATA_SPAWN src_addr, dest_addr, size, fp, ip BLOCKDATA_SYNC src_addr, dest_addr, size, fp, ss_off • Split_phase Data Requests GET_SPAWN src_addr, dest_addr, fp, ip GET_SYNC src_addr, dest_addr, fp, ss_off GET_BLOCK_SPAWN src_addr, dest_addr, size, fp, ip GET_BLOCK_SYNC src_addr, dest_addr, size, fp, ip • Function Invocation INVOKE dest_PE, f_name, no_params, params TOKEN f_name, no_params, params END_FUNCTION \course\eleg652-03F\Topic5b-652.ppt

  9. Threaded-C: A Base-Language • To serve as a target language for high-level language compilers • To serve as a machine language for the EARTH architecture \course\eleg652-03F\Topic5b-652.ppt

  10. The Role of Threaded-C C Fortran High-level Language Translation Users Threaded-C Threaded-C Compiler EARTH Platforms \course\eleg652-03F\Topic5b-652.ppt

  11. Features of Threaded Programming • Thread partition • Thread length vs useful parallelism • Where to “cut”? • Split-phase synchronization and communication (e.g. GET_SYNC) • Parallel threaded function invocation • Dynamic load balancing (e..g. TOKEN) • Other advanced features Latency tolerance and management \course\eleg652-03F\Topic5b-652.ppt

  12. EARTH-MANNA Benchmark Programs • Ray Tracing is a program for rendering 3-D photo-realistic images • Protein Folding is an application which computes all possible folding structures of a given polymer • TSP is an application to find a minimal-length Hamiltonian cycle in a graph with N cities and weighted paths. • Tomcatv is one of the SPEC benchmarks which operates upon a mesh • Paraffins is another application which enumerates the distinct isomers of paraffins • 2D-SLT is a program implementing the 2D-SLT Semi-Lagrangian Advection Model on a Gaussian Grid for numerical weather predication • N-queens is a benchmark program typical of graph searching problem. \course\eleg652-03F\Topic5b-652.ppt

  13. Parallel Function Invocation fib n-2 fib n-3 SYNC slots local vars fib n-1 fib n-2 caller’s <fp,ip> Links between frames fib n Tree of “Activation Frames” \course\eleg652-03F\Topic5b-652.ppt

  14. result n done fib 0 0 If n < 2 DATA_RSYNC (1, result, done) else { TOKEN (fib, n-1, & sum1, slot_1); TOKEN (fib, n-2, & sum2, slot_1); } END_THREAD( ) ; 2 2 THREAD-1; DATA_RSYNC (sum1 + sum2, result, done); END_THREAD ( ) ; END_FUNCTION The Fibonacci Example \course\eleg652-03F\Topic5b-652.ppt

  15. Matrix Multiplication void main ( ) { int i, j, k; float sum; for (i=0; i < N; i++) for (j=0; j < N ; j++) { sum = 0; for (k=0; k < N; k++) sum = sum + a [i] [k] * b [k] [j] c [i] [j] = sum; } } Sequential Version \course\eleg652-03F\Topic5b-652.ppt

  16. result a b done inner 0 0 2 2 THREAD-1; for (i=0; i<N; i++ ); sum = sum + (row_a[i] * column_b[i]); DATA_RSYNC (sum, result, done); END_THREAD ( ) ; BLKMOV_SYNC (a, row_a, N, slot_1); BLKMOV_SYNC (b, column_b, N, slot_1); sum = 0; END_THREAD; END_FUNCTION The Inner Product Example \course\eleg652-03F\Topic5b-652.ppt

  17. main 0 0 for (i=0; i<N; i++) for (j=0; j<N; j++) { row_a = a [i]; column_b = b [j]; TOKEN (inner, &c[I][j], row_a, column_b,slot_1); } END_THREAD; N*N N*N THREAD-1; RETURN ( ); END- THREAD The Matrix Multiplication Example \course\eleg652-03F\Topic5b-652.ppt

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