#include "pvm3.h"
#include <pthread.h>
#include <cl.h>
#include <malloc.h>
float *x, *y;
#define PROC (8)
float e_vec[PROC];
int n_thread0, n_thread1;
// kernel
#define BLOCK (512)
const char *source =
"__kernel void sub1(__global float* fx,\
__global const float* fy,\
__local float* se, __global float* fe) {\
const unsigned int t = get_global_id(0);\
const unsigned int b = get_group_id(0);\
const unsigned block = 512;\
const unsigned int i = block*b+t;\
float e;\
/* do computation */\
fx[t] += ( fy[t+2] + fy[t] )*.5;\
e = fy[t+1] * fy[t+1];\
/* reduction */\
se[t] = e;\
barrier(CLK_LOCAL_MEM_FENCE);\
if (t<256) {\
se[t] += se[t+256];\
barrier(CLK_LOCAL_MEM_FENCE);\
}\
if (t<128) {\
se[t] += se[t+128];\
barrier(CLK_LOCAL_MEM_FENCE);\
}\
if (t<64) {\
se[t] += se[t+64];\
barrier(CLK_LOCAL_MEM_FENCE);\
}\
if (t<32) {\
se[t] += se[t+32];\
se[t] += se[t+16];\
se[t] += se[t+8];\
se[t] += se[t+4];\
se[t] += se[t+2];\
se[t] += se[t+1];\
}\
if (t==0)\
fe[b] = se[0];\
}";
void *thread1(void *arg) {
int p = (int)arg;
int n0 = n_thread0 + (p * (n_thread1-n_thread0)) / PROC;
int n1 = n_thread0 + ((p+1) * (n_thread1-n_thread0)) / PROC;
// allocate GPU
cl_context ct = clCreateContextFromType(0, CL_DEVICE_TYPE_GPU, 0, 0, 0);
size_t ctsize;
clGetContextInfo(ct, CL_CONTEXT_DEVICES, 0, 0, &ctsize);
cl_device_id *aDevices = (cl_device_id*)malloc(ctsize);
clGetContextInfo(ct, CL_CONTEXT_DEVICES, ctsize, aDevices, 0);
// compile kernel
cl_program prog = clCreateProgramWithSource(ct, 1, &source, 0, 0);
clBuildProgram(prog, 0, 0, 0, 0, 0);
cl_kernel kern = clCreateKernel(prog, "sub1", 0);
float e = 0;
// pick GPU
cl_command_queue queue = clCreateCommandQueue(ct, aDevices[p], 0, 0);
// allocate GPU memory
cl_mem fx = clCreateBuffer(ct, CL_MEM_READ_WRITE | CL_MEM_COPY_HOST_PTR,
(n1-n0)*sizeof(cl_float), &x[n0], 0);
cl_mem fy = clCreateBuffer(ct, CL_MEM_READ_ONLY | CL_MEM_COPY_HOST_PTR,
(n1-n0+2)*sizeof(cl_float), &y[n0-1], 0);
cl_mem se = clCreateBuffer(ct, CL_MEM_READ_WRITE,
BLOCK*sizeof(cl_float), 0, 0);
cl_mem fe = clCreateBuffer(ct, CL_MEM_WRITE_ONLY,
(n1-n0)/BLOCK*sizeof(cl_float), 0, 0);
clSetKernelArg(kern, 0, sizeof(cl_mem), (void *)&fx);
clSetKernelArg(kern, 1, sizeof(cl_mem), (void *)&fx);
clSetKernelArg(kern, 2, sizeof(cl_mem), (void *)&se);
clSetKernelArg(kern, 3, sizeof(cl_mem), (void *)&fe);
float *d = new float[(n1-n0)/BLOCK];
// call GPU
const unsigned int size = BLOCK;
const unsigned int dim = n1-n0+2;
clEnqueueNDRangeKernel(queue, kern, 1, 0, &dim, &size, 0, 0, 0);
// copy to host memory
clEnqueueReadBuffer(queue, fx, CL_TRUE, 0,
(n1-n0) * sizeof(cl_float), &x[n0], 0, 0, 0);
clEnqueueReadBuffer(queue, fe, CL_TRUE, 0,
(n1-n0) * sizeof(cl_float), d, 0, 0, 0);
float ee = 0;
for (int i=0; i<(n1-n0)/BLOCK; ++i)
ee += d[i];
e += ee;
delete[] d;
// release GPU memory
clReleaseMemObject(fx);
clReleaseMemObject(fy);
clReleaseMemObject(se);
clReleaseMemObject(fe);
e_vec[p] = e;
return (void*) 0;
}
int main(int argc, char *argv[]) {
int n = ...;
if (pvm_parent() == PvmNoParent) {
#define N (4)
int tid[N];
pvm_spawn("program", argv, PvmTaskDefault, (char*)0, N, &tid[0]);
} else {
int mytid = pvm_mytid();
int *tids, me = -1;
int ntids = pvm_siblings(&tids);
for (int i=0; i<ntids; ++i)
if ( tids[i] == mytid) {
me = i;
break;
}
int p_left = -1, p_right = -1;
if (me > 0)
p_left = tids[me-1];
if (me < ntids-1)
p_right = tids[me+1];
int n_local0 = 1 + (me * (n-1)) / ntids;
int n_local1 = 1 + ((me+1) * (n-1)) / ntids;
pvm_joingroup("worker");
// allocate only local part + ghost zone of the arrays x,y
float *x, *y;
x = new float[n_local1 - n_local0 + 2];
y = new float[n_local1 - n_local0 + 2];
x -= (n_local0 - 1);
y -= (n_local0 - 1);
... // fill x, y
// fill ghost zone
if (p_left != -1) {
pvm_initsend(PvmDataDefault);
pvm_pkfloat(&y[n_local0], 1, 1);
int msgtag = 1;
pvm_send(p_left, msgtag);
}
if (p_right != -1) {
int msgtag = 1;
pvm_recv(p_right, msgtag);
pvm_upkfloat(&y[n_local1], 1, 1);
pvm_initsend(PvmDataDefault);
pvm_pkfloat(&y[n_local1-1], 1, 1);
msgtag = 2;
pvm_send(p_right, msgtag);
}
if (p_left != -1) {
int msgtag = 2;
pvm_recv(p_left, msgtag);
pvm_upkfloat(&y[n_local0-1], 1, 1);
}
pthread_t threads[PROC];
pthread_attr_t attr;
pthread_attr_init(&attr);
n_thread0 = n_local0;
n_thread1 = n_local1;
float e = 0;
// start threads and wait for termination
for (int p=0; p<PROC; ++p)
pthread_create(&threads[p], &attr, thread1, (void *)p);
for (int p=0; p<PROC; ++p) {
pthread_join(threads[p], NULL);
e += e_vec[p];
}
int msgtag = 3;
pvm_reduce(PvmSum, &e, 1, PVM_FLOAT, msgtag, "worker", tids[0]);
msgtag = 4;
if (me==0) {
pvm_initsend(PvmDataDefault);
pvm_pkfloat(&e, 1, 1);
pvm_bcast("worker", msgtag);
} else {
pvm_recv(tids[0], msgtag);
pvm_upkfloat(&e, 1, 1);
}
... // output x, e
x += (n_local0 - 1);
y += (n_local0 - 1);
delete[] x, y;
}
pvm_exit();
return 0;
}
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