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Modify stencil example to do separate runs with and without task parallelism.

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This commit is contained in:
Matt Pharr
2011-08-30 05:08:21 -07:00
parent ad9e66650d
commit a94cabc692
2 changed files with 74 additions and 22 deletions
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37
examples/stencil/stencil.cpp
View File

@@ -116,20 +116,38 @@ int main() {
InitData(Nx, Ny, Nz, Aispc, vsq);
//
// Compute the image using the ispc implementation; report the minimum
// time of three runs.
// Compute the image using the ispc implementation on one core; report
// the minimum time of three runs.
//
double minISPC = 1e30;
double minTimeISPC = 1e30;
for (int i = 0; i < 3; ++i) {
reset_and_start_timer();
loop_stencil_ispc(0, 6, width, Nx - width, width, Ny - width,
width, Nz - width, Nx, Ny, Nz, coeff, vsq,
Aispc[0], Aispc[1]);
double dt = get_elapsed_mcycles();
minISPC = std::min(minISPC, dt);
minTimeISPC = std::min(minTimeISPC, dt);
}
printf("[stencil ispc]:\t\t\t[%.3f] million cycles\n", minISPC);
printf("[stencil ispc 1 core]:\t\t[%.3f] million cycles\n", minTimeISPC);
InitData(Nx, Ny, Nz, Aispc, vsq);
//
// Compute the image using the ispc implementation with tasks; report
// the minimum time of three runs.
//
double minTimeISPCTasks = 1e30;
for (int i = 0; i < 3; ++i) {
reset_and_start_timer();
loop_stencil_ispc_tasks(0, 6, width, Nx - width, width, Ny - width,
width, Nz - width, Nx, Ny, Nz, coeff, vsq,
Aispc[0], Aispc[1]);
double dt = get_elapsed_mcycles();
minTimeISPCTasks = std::min(minTimeISPCTasks, dt);
}
printf("[stencil ispc + tasks]:\t\t[%.3f] million cycles\n", minTimeISPCTasks);
InitData(Nx, Ny, Nz, Aserial, vsq);
@@ -137,19 +155,20 @@ int main() {
// And run the serial implementation 3 times, again reporting the
// minimum time.
//
double minSerial = 1e30;
double minTimeSerial = 1e30;
for (int i = 0; i < 3; ++i) {
reset_and_start_timer();
loop_stencil_serial(0, 6, width, Nx-width, width, Ny - width,
width, Nz - width, Nx, Ny, Nz, coeff, vsq,
Aserial[0], Aserial[1]);
double dt = get_elapsed_mcycles();
minSerial = std::min(minSerial, dt);
minTimeSerial = std::min(minTimeSerial, dt);
}
printf("[stencil serial]:\t\t[%.3f] millon cycles\n", minSerial);
printf("[stencil serial]:\t\t[%.3f] millon cycles\n", minTimeSerial);
printf("\t\t\t\t(%.2fx speedup from ISPC)\n", minSerial/minISPC);
printf("\t\t\t\t(%.2fx speedup from ISPC, %.2f from ISPC + tasks)\n",
minTimeSerial / minTimeISPC, minTimeSerial / minTimeISPCTasks);
// Check for agreement
int offset = 0;

59
examples/stencil/stencil.ispc
View File

@@ -32,7 +32,7 @@
*/
static task void
static void
stencil_step(uniform int x0, uniform int x1,
uniform int y0, uniform int y1,
uniform int z0, uniform int z1,
@@ -67,14 +67,26 @@ stencil_step(uniform int x0, uniform int x1,
}
export void loop_stencil_ispc(uniform int t0, uniform int t1,
uniform int x0, uniform int x1,
uniform int y0, uniform int y1,
uniform int z0, uniform int z1,
uniform int Nx, uniform int Ny, uniform int Nz,
uniform const float coef[4],
uniform const float vsq[],
uniform float Aeven[], uniform float Aodd[])
static task void
stencil_step_task(uniform int x0, uniform int x1,
uniform int y0, uniform int y1,
uniform int z0, uniform int z1,
uniform int Nx, uniform int Ny, uniform int Nz,
uniform const float coef[4], uniform const float vsq[],
uniform const float Ain[], uniform float Aout[]) {
stencil_step(x0, x1, y0, y1, z0, z1, Nx, Ny, Nz, coef, vsq, Ain, Aout);
}
export void
loop_stencil_ispc_tasks(uniform int t0, uniform int t1,
uniform int x0, uniform int x1,
uniform int y0, uniform int y1,
uniform int z0, uniform int z1,
uniform int Nx, uniform int Ny, uniform int Nz,
uniform const float coef[4],
uniform const float vsq[],
uniform float Aeven[], uniform float Aodd[])
{
for (uniform int t = t0; t < t1; ++t) {
// Parallelize across cores as well: each task will work on a slice
@@ -83,14 +95,35 @@ export void loop_stencil_ispc(uniform int t0, uniform int t1,
uniform int dz = 1;
for (uniform int z = z0; z < z1; z += dz) {
if ((t & 1) == 0)
launch < stencil_step(x0, x1, y0, y1, z, z+dz, Nx, Ny, Nz, coef, vsq,
Aeven, Aodd) >;
launch < stencil_step_task(x0, x1, y0, y1, z, z+dz, Nx, Ny, Nz,
coef, vsq, Aeven, Aodd) >;
else
launch < stencil_step(x0, x1, y0, y1, z, z+dz, Nx, Ny, Nz, coef, vsq,
Aodd, Aeven) >;
launch < stencil_step_task(x0, x1, y0, y1, z, z+dz, Nx, Ny, Nz,
coef, vsq, Aodd, Aeven) >;
}
// We need to wait for all of the launched tasks to finish before
// starting the next iteration.
sync;
}
}
export void
loop_stencil_ispc(uniform int t0, uniform int t1,
uniform int x0, uniform int x1,
uniform int y0, uniform int y1,
uniform int z0, uniform int z1,
uniform int Nx, uniform int Ny, uniform int Nz,
uniform const float coef[4],
uniform const float vsq[],
uniform float Aeven[], uniform float Aodd[])
{
for (uniform int t = t0; t < t1; ++t) {
if ((t & 1) == 0)
stencil_step(x0, x1, y0, y1, z0, z1, Nx, Ny, Nz, coef, vsq,
Aeven, Aodd);
else
stencil_step(x0, x1, y0, y1, z0, z1, Nx, Ny, Nz, coef, vsq,
Aodd, Aeven);
}
}