int sum;... sum = sum + c?

Transcription

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3 int sum;... sum = sum + c?

4 Version Cores Time (secs) Speedup

5 manycore

6 Message Passing Interface

7 mpiexec

8 int main( ) { int ; char ; } MPI_Init( ); MPI_Comm_size(, &N); MPI_Comm_rank(, &R); gethostname( ); cout << "Hello from master!"; for (int w=1; w<n; ) { MPI_Recv(buf,, w, ); cout << buf; } MPI_Finalize(); return 0; int main( ) { int ; char ; } MPI_Init( ); MPI_Comm_size(, &N); MPI_Comm_rank(, &R); gethostname( ); sprintf_s(buf, "Hi from %d", R); MPI_Send(buf,, 0, ); MPI_Finalize(); return 0;

9 mpiexec -n Size Install Visual Studio PowerCommands to open command prompt from within Visual Studio:

10 SPMD Single-Program, Multiple-Data int main( ) int main(int argc, char* argv[]) { { int ; MPI_Init(&argc, &argv); char ; MPI_Comm_size(MPI_COMM_WORLD, &N); MPI_Comm_rank(MPI_COMM_WORLD, &R); MPI_Init( ); gethostname(host, 128 /*buf size*/); MPI_Comm_size( ); MPI_Comm_rank( ); if (R > 0) { // "worker" processes: gethostname( );. cout << "Hello } " ; for ( ) { else { // "master" process: MPI_Recv( ); cout << buf. << ; } }//else } MPI_Finalize(); MPI_Finalize(); return 0; return 0; } } int main( ) { int ; char ; MPI_Init( ); MPI_Comm_size( ); MPI_Comm_rank( ); gethostname( ); sprintf_s( ); MPI_Send( ); MPI_Finalize(); return 0;

11 #include <iostream> #include <winsock2.h> /* requires: Ws2_32.lib */ #include <mpi.h> /* requires msmpi.lib */ int main(int argc, char* argv[]) { int R, N; char host[128], buf[256]; MPI_Init(&argc, &argv); MPI_Comm_size(MPI_COMM_WORLD, &N); // number of processes involved in run: MPI_Comm_rank(MPI_COMM_WORLD, &R); // my rank: 0 <= R < N: gethostname(host, size(host)/sizeof(host[0])); // name of machine we are running on: if (R > 0) { // "worker" processes send their hello to "master": sprintf_s(buf, sizeof(buf)/sizeof(buf[0]), "Hello from process %d on %s.", R, host); MPI_Send(buf, (int) strlen(buf)+1, MPI_CHAR, 0 /*dest*/, 0 /*tag*/, MPI_COMM_WORLD); } else { // "master" process collects messages & outputs: MPI_Status stat; cout << "Hello from process 0 on " << host << "." << endl; for (int w = 1; w < N; w++) { MPI_Recv(buf, size(buf)/sizeof(buf[0]), MPI_CHAR, MPI_ANY_SOURCE, 0, MPI_COMM_WORLD, &stat); cout << buf << endl; } }//else } MPI_Finalize(); return 0;

12 #include <mpi.h> mpi.h MPI_Init int main(int argc, char* argv[]) { int rank, N; MPI_Finalize MPI_Init(&argc, &argv); MPI_Comm_size(MPI_COMM_WORLD, &N); MPI_Comm_rank(MPI_COMM_WORLD, &rank);... MPI_Comm_size MPI_Comm_rank } MPI_Finalize(); return 0;

13 envelopes source destination tag communicator

14 int MPI_Send( void* buf, int count, MPI_Datatype datatype, int dest, int tag, MPI_Comm communicator ); int MPI_Recv( void* buf, int count, MPI_Datatype datatype, int src, int tag, MPI_Comm communicator, MPI_Status* status );

15 int MPI_Send( void* buf, int count, MPI_Datatype datatype, int dest, int tag, MPI_Comm comm );

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17 double pi; int dest = 3, tag = 0; pi = 3.14; MPI_Send(&pi, 1, MPI_DOUBLE, dest, tag, MPI_COMM_WORLD); pi++; MPI_Send(&pi, 1, MPI_DOUBLE, dest, tag, MPI_COMM_WORLD);

18 int MPI_Recv( void* buf, int count, MPI_Datatype datatype, int src, int tag, MPI_Comm comm, MPI_Status* status );

19 double d; int src, tag; MPI_Status status; MPI_Recv(&d, 1, MPI_DOUBLE, MPI_ANY_SOURCE, MPI_ANY_TAG, MPI_COMM_WORLD, &status); src = status.mpi_source; // status contains process # of sender tag = status.mpi_tag; // status contains tag used by sender cout << "Received " << d << " from process " << src << endl; MPI_Recv(&d, 1, MPI_DOUBLE, src, tag, MPI_COMM_WORLD, &status); cout << "Received " << d << " from process " << src << endl; MPI_ANY_SOURCE MPI_ANY_TAG

20 double int MPI_Status *results; count; status; MPI_Probe(src, tag, comm, &status); // probe for msg from src MPI_Get_count(&status, MPI_DOUBLE, &count); // # elements in msg results = new double[count]; // allocate memory for data: MPI_Recv(results, count, MPI_DOUBLE, src, tag, ); // now recv: MPI_Probe blocks waiting for a matching message, much like MPI_Recv

21 mpiexec

22 ...

23 int main(int argc, char* argv[]) { int myrank, a; MPI_Init(&argc, &argv); MPI_Comm_rank(MPI_COMM_WORLD, &myrank); cin >> a; cout << "Process " << myrank << " just input " << a << endl; cerr << "Testing." << endl; use Task properties to redirect and collect

24 ...

25 RAM Version Cores (1 Node) Time (secs) Speedup

26 Kernel By-Pass Socket- Based App MPI App MS-MPI TCP/Ethernet Networking Windows Sockets (Winsock + WSD) RDMA Networking Networking WinSock Networking Hardware Hardware Direct NetworkDirect Networking Provider Provider Hardware Networking Networking Hardware Hardware User Mode Access Layer TCP IP NDIS Networking Networking Mini-port Hardware Hardware Driver Networking Hardware Networking Hardware Hardware Driver Networking Hardware Networking Hardware Networking Hardware

27 e.g. matching a fingerprint against a database of fingerprints e.g. running N distinct Monte Carlo simulations across the cluster // send out initial work: for (w=1; w < numprocs; w++) MPI_Send(work,, w, ); // as workers finish, send out more work: for (sim=0; sim < NUM_SIMS; sim++) { MPI_Recv(, &status); // worker is done w = status.mpi_source; // which worker? } MPI_Send(work,, w, ); // more work

28 simrun = 0; simcompleted = 0; for (w=1; w < numprocs; w++) { //start simrun++; // initial run for w: params =...; MPI_Send(params,, w, WORK, ); } while (simcompleted < NUM_SIMS) { MPI_Recv(results,, MPI_ANY_SOURCE, DONE,, &status); } if (simrun < NUM_SIMS) { // more? simrun++; // next run: params =...; w = status.mpi_source; MPI_Send(params,, w, WORK, ); } ProcessResults(results); simcompleted++; // wait for work (or exit): MPI_Recv(params,, 0 /*master*/, MPI_ANY_TAG, ); while (status.mpi_tag!= EXIT) { // we have work to do: results = RunSimulation(params); } /* tags */ #define WORK 1 #define DONE 2 #define EXIT 3 // send results back: MPI_Send(results,, 0, DONE, ); // wait for more work (or exit): MPI_Recv(params,, 0, MPI_ANY_TAG, ); // done, tell workers to exit: for (w=1; w < numprocs; w++) MPI_Send(NULL,, w, EXIT, );

29 MPI forces you to think carefully about design, which is a good thing. W. Gropp & E. Lusk Argonne National Lab

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31 complete msmpi.lib mpi.h mpiexec

32 mpi.h msmpi.lib

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35 msmpi.lib Ws2_32.lib gethostname msmpi.lib Ws2_32.lib

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