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switch boundary exchange / stencil direction

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Contiguous staging vectors are required for multi-d exchange
when the non outer most dimension is exchanged. The previous
version was exchanging y, the outer most dimension, and the
data was already contiguous.
This commit is contained in:
Bryce Allen
2022-10-29 12:41:12 +00:00
parent 936f0851c8
commit b2ed53adc1
1 changed files with 72 additions and 58 deletions
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118
mpi_stencil2d_gt.cc
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@@ -27,6 +27,16 @@
using namespace gt::placeholders; using namespace gt::placeholders;
inline void check(const char* fname, int line, int mpi_rval)
{
if (mpi_rval != MPI_SUCCESS) {
printf("%s:%d error %d\n", fname, line, mpi_rval);
exit(2);
}
}
#define CHECK(x) check(__FILE__, __LINE__, (x))
// little hack to make code parameterizable on managed vs device memory // little hack to make code parameterizable on managed vs device memory
namespace gt namespace gt
{ {
@@ -65,18 +75,18 @@ static const gt::gtensor<double, 1> stencil5 = {1.0 / 12.0, -2.0 / 3.0, 0.0,
/* /*
* Return unevaluated expression that calculates the 1d stencil in the * Return unevaluated expression that calculates the 1d stencil in the
* second dimension of a 2d array. * first dimension of a 2d array.
* *
* Size of the result will be size of z with minus 4 in second dimension. * Size of the result will be size of z with minus 4 in second dimension.
*/ */
inline auto stencil2d_1d_5(const gt::gtensor_device<double, 2>& z, inline auto stencil2d_1d_5(const gt::gtensor_device<double, 2>& z,
const gt::gtensor<double, 1>& stencil) const gt::gtensor<double, 1>& stencil)
{ {
return stencil(0) * z.view(_all, _s(0, -4)) + return stencil(0) * z.view(_s(0, -4), _all) +
stencil(1) * z.view(_all, _s(1, -3)) + stencil(1) * z.view(_s(1, -3), _all) +
stencil(2) * z.view(_all, _s(2, -2)) + stencil(2) * z.view(_s(2, -2), _all) +
stencil(3) * z.view(_all, _s(3, -1)) + stencil(3) * z.view(_s(3, -1), _all) +
stencil(4) * z.view(_all, _s(4, _)); stencil(4) * z.view(_s(4, _), _all);
} }
void set_rank_device(int n_ranks, int rank) void set_rank_device(int n_ranks, int rank)
@@ -104,11 +114,11 @@ void set_rank_device(int n_ranks, int rank)
// exchange in non-contiguous second dimension, staging into contiguous buffers // exchange in non-contiguous second dimension, staging into contiguous buffers
// on device // on device
void boundary_exchange_y(MPI_Comm comm, int world_size, int rank, void boundary_exchange_x(MPI_Comm comm, int world_size, int rank,
gt::gtensor_device<double, 2>& d_z, int n_bnd, gt::gtensor_device<double, 2>& d_z, int n_bnd,
bool stage_host = false) bool stage_host = false)
{ {
auto buf_shape = gt::shape(d_z.shape(0), n_bnd); auto buf_shape = gt::shape(n_bnd, d_z.shape(1));
gt::gtensor_device<double, 2> sbuf_l(buf_shape); gt::gtensor_device<double, 2> sbuf_l(buf_shape);
gt::gtensor_device<double, 2> sbuf_r(buf_shape); gt::gtensor_device<double, 2> sbuf_r(buf_shape);
gt::gtensor_device<double, 2> rbuf_r(buf_shape); gt::gtensor_device<double, 2> rbuf_r(buf_shape);
@@ -133,13 +143,13 @@ void boundary_exchange_y(MPI_Comm comm, int world_size, int rank,
// start async copy of ghost points into send buffers // start async copy of ghost points into send buffers
if (rank_l >= 0) { if (rank_l >= 0) {
sbuf_l = d_z.view(_all, _s(n_bnd, 2 * n_bnd)); sbuf_l = d_z.view(_s(n_bnd, 2 * n_bnd), _all);
if (stage_host) { if (stage_host) {
gt::copy(sbuf_l, h_sbuf_l); gt::copy(sbuf_l, h_sbuf_l);
} }
} }
if (rank_r <= world_size) { if (rank_r <= world_size) {
sbuf_r = d_z.view(_all, _s(-2 * n_bnd, -n_bnd)); sbuf_r = d_z.view(_s(-2 * n_bnd, -n_bnd), _all);
if (stage_host) { if (stage_host) {
gt::copy(sbuf_r, h_sbuf_r); gt::copy(sbuf_r, h_sbuf_r);
} }
@@ -153,8 +163,8 @@ void boundary_exchange_y(MPI_Comm comm, int world_size, int rank,
} else { } else {
rbuf_l_data = rbuf_l.data().get(); rbuf_l_data = rbuf_l.data().get();
} }
MPI_Irecv(rbuf_l_data, rbuf_l.size(), MPI_DOUBLE, rank_l, 123, comm, CHECK(MPI_Irecv(rbuf_l_data, rbuf_l.size(), MPI_DOUBLE, rank_l, 123, comm,
&req_l[0]); &req_l[0]));
} }
if (rank_r < world_size) { if (rank_r < world_size) {
@@ -164,8 +174,8 @@ void boundary_exchange_y(MPI_Comm comm, int world_size, int rank,
} else { } else {
rbuf_r_data = rbuf_r.data().get(); rbuf_r_data = rbuf_r.data().get();
} }
MPI_Irecv(rbuf_r_data, rbuf_r.size(), MPI_DOUBLE, rank_r, 456, comm, CHECK(MPI_Irecv(rbuf_r_data, rbuf_r.size(), MPI_DOUBLE, rank_r, 456, comm,
&req_r[0]); &req_r[0]));
} }
// wait for send buffer fill // wait for send buffer fill
@@ -179,8 +189,8 @@ void boundary_exchange_y(MPI_Comm comm, int world_size, int rank,
} else { } else {
sbuf_l_data = sbuf_l.data().get(); sbuf_l_data = sbuf_l.data().get();
} }
MPI_Isend(sbuf_l_data, sbuf_l.size(), MPI_DOUBLE, rank_l, 456, comm, CHECK(MPI_Isend(sbuf_l_data, sbuf_l.size(), MPI_DOUBLE, rank_l, 456, comm,
&req_l[1]); &req_l[1]));
} }
if (rank_r < world_size) { if (rank_r < world_size) {
@@ -190,31 +200,35 @@ void boundary_exchange_y(MPI_Comm comm, int world_size, int rank,
} else { } else {
sbuf_r_data = sbuf_r.data().get(); sbuf_r_data = sbuf_r.data().get();
} }
MPI_Isend(sbuf_r_data, sbuf_r.size(), MPI_DOUBLE, rank_r, 123, comm, CHECK(MPI_Isend(sbuf_r_data, sbuf_r.size(), MPI_DOUBLE, rank_r, 123, comm,
&req_r[1]); &req_r[1]));
} }
// wait for send/recv to complete, then copy data back into main data array // wait for send/recv to complete, then copy data back into main data array
int mpi_rval; int mpi_rval;
if (rank_l >= 0) { if (rank_l >= 0) {
mpi_rval = MPI_Waitall(2, req_l, MPI_STATUSES_IGNORE); MPI_Status status[2];
mpi_rval = MPI_Waitall(2, req_l, status);
if (mpi_rval != MPI_SUCCESS) { if (mpi_rval != MPI_SUCCESS) {
printf("send_l error: %d\n", mpi_rval); printf("send_l error: %d (%d %d)\n", mpi_rval, status[0].MPI_ERROR,
status[1].MPI_ERROR);
} }
if (stage_host) { if (stage_host) {
gt::copy(h_rbuf_l, rbuf_l); gt::copy(h_rbuf_l, rbuf_l);
} }
d_z.view(_all, _s(0, n_bnd)) = rbuf_l; d_z.view(_s(0, n_bnd), _all) = rbuf_l;
} }
if (rank_r < world_size) { if (rank_r < world_size) {
mpi_rval = MPI_Waitall(2, req_r, MPI_STATUSES_IGNORE); MPI_Status status[2];
mpi_rval = MPI_Waitall(2, req_r, status);
if (mpi_rval != MPI_SUCCESS) { if (mpi_rval != MPI_SUCCESS) {
printf("send_r error: %d\n", mpi_rval); printf("send_r error: %d (%d %d)\n", mpi_rval, status[0].MPI_ERROR,
status[1].MPI_ERROR);
} }
if (stage_host) { if (stage_host) {
gt::copy(h_rbuf_r, rbuf_r); gt::copy(h_rbuf_r, rbuf_r);
} }
d_z.view(_all, _s(-n_bnd, _)) = rbuf_r; d_z.view(_s(-n_bnd, _), _all) = rbuf_r;
} }
gt::synchronize(); gt::synchronize();
@@ -245,10 +259,10 @@ int main(int argc, char** argv)
int world_size, world_rank, device_id; int world_size, world_rank, device_id;
uint32_t vendor_id; uint32_t vendor_id;
MPI_Init(NULL, NULL); CHECK(MPI_Init(NULL, NULL));
MPI_Comm_size(MPI_COMM_WORLD, &world_size); CHECK(MPI_Comm_size(MPI_COMM_WORLD, &world_size));
MPI_Comm_rank(MPI_COMM_WORLD, &world_rank); CHECK(MPI_Comm_rank(MPI_COMM_WORLD, &world_rank));
if (n_global % world_size != 0) { if (n_global % world_size != 0) {
printf("%d nmpi (%d) must be divisor of domain size (%d), exiting\n", printf("%d nmpi (%d) must be divisor of domain size (%d), exiting\n",
@@ -272,50 +286,50 @@ int main(int argc, char** argv)
printf("stage_host = %d\n", stage_host); printf("stage_host = %d\n", stage_host);
} }
auto h_z = gt::empty<double>({n_global, n_local_with_ghost}); auto h_z = gt::empty<double>({n_local_with_ghost, n_global});
auto d_z = gt::empty_device<double>({n_global, n_local_with_ghost}); auto d_z = gt::empty_device<double>({n_local_with_ghost, n_global});
auto h_dzdy_numeric = gt::empty<double>({n_global, n_local}); auto h_dzdx_numeric = gt::empty<double>({n_local, n_global});
auto h_dzdy_actual = gt::empty<double>({n_global, n_local}); auto h_dzdx_actual = gt::empty<double>({n_local, n_global});
auto d_dzdy_numeric = gt::empty_device<double>({n_global, n_local}); auto d_dzdx_numeric = gt::empty_device<double>({n_local, n_global});
double lx = 8; double lx = 8;
double dx = lx / n_global; double dx = lx / n_global;
double lx_local = lx / world_size; double lx_local = lx / world_size;
double scale = n_global / lx; double scale = n_global / lx;
auto fn = [](double x, double y) { return x * x + y * y; }; auto fn = [](double x, double y) { return x * x * x + y * y; };
auto fn_dzdy = [](double x, double y) { return 2 * x; }; auto fn_dzdx = [](double x, double y) { return 3 * x * x; };
struct timespec start, end; struct timespec start, end;
double iter_time = 0.0; double iter_time = 0.0;
double total_time = 0.0; double total_time = 0.0;
double x_start = world_rank * lx_local; double x_start = world_rank * lx_local;
for (int i = 0; i < n_local; i++) {
double xtmp = x_start + i * dx;
for (int j = 0; j < n_global; j++) { for (int j = 0; j < n_global; j++) {
double ytmp = j * dx; double ytmp = j * dx;
h_z(j, i + n_bnd) = fn(xtmp, ytmp); for (int i = 0; i < n_local; i++) {
h_dzdy_actual(j, i) = fn_dzdy(xtmp, ytmp); double xtmp = x_start + i * dx;
h_z(i + n_bnd, j) = fn(xtmp, ytmp);
h_dzdx_actual(i, j) = fn_dzdx(xtmp, ytmp);
} }
} }
// fill boundary points on ends // fill boundary points on ends
if (world_rank == 0) { if (world_rank == 0) {
for (int i = 0; i < n_bnd; i++) {
double xtmp = (i - n_bnd) * dx;
for (int j = 0; j < n_global; j++) { for (int j = 0; j < n_global; j++) {
double ytmp = j * dx; double ytmp = j * dx;
h_z(j, i) = fn(xtmp, ytmp); for (int i = 0; i < n_bnd; i++) {
double xtmp = (i - n_bnd) * dx;
h_z(i, j) = fn(xtmp, ytmp);
} }
} }
} }
if (world_rank == world_size - 1) { if (world_rank == world_size - 1) {
for (int i = 0; i < n_bnd; i++) {
double xtmp = lx + i * dx;
for (int j = 0; j < n_global; j++) { for (int j = 0; j < n_global; j++) {
double ytmp = j * dx; double ytmp = j * dx;
h_z(j, n_bnd + n_local + i) = fn(xtmp, ytmp); for (int i = 0; i < n_bnd; i++) {
double xtmp = lx + i * dx;
h_z(n_bnd + n_local + i, j) = fn(xtmp, ytmp);
} }
} }
} }
@@ -334,7 +348,7 @@ int main(int argc, char** argv)
for (int i = 0; i < n_warmup + n_iter; i++) { for (int i = 0; i < n_warmup + n_iter; i++) {
clock_gettime(CLOCK_MONOTONIC, &start); clock_gettime(CLOCK_MONOTONIC, &start);
boundary_exchange_y(MPI_COMM_WORLD, world_size, world_rank, d_z, n_bnd, boundary_exchange_x(MPI_COMM_WORLD, world_size, world_rank, d_z, n_bnd,
stage_host); stage_host);
clock_gettime(CLOCK_MONOTONIC, &end); clock_gettime(CLOCK_MONOTONIC, &end);
iter_time = iter_time =
@@ -345,27 +359,27 @@ int main(int argc, char** argv)
} }
// do some calculation, to try to more closely simulate what happens in GENE // do some calculation, to try to more closely simulate what happens in GENE
d_dzdy_numeric = stencil2d_1d_5(d_z, stencil5) * scale; d_dzdx_numeric = stencil2d_1d_5(d_z, stencil5) * scale;
gt::synchronize(); gt::synchronize();
} }
printf("%d/%d exchange time %0.8f\n", world_rank, world_size, printf("%d/%d exchange time %0.8f\n", world_rank, world_size,
total_time / n_iter); total_time / n_iter);
gt::copy(d_dzdy_numeric, h_dzdy_numeric); gt::copy(d_dzdx_numeric, h_dzdx_numeric);
/* /*
for (int i = 0; i < 5; i++) { for (int i = 0; i < 5; i++) {
printf("%d la %f\n%d ln %f\n", world_rank, h_dzdy_actual(8, i), world_rank, printf("%d la %f\n%d ln %f\n", world_rank, h_dzdx_actual(8, i), world_rank,
h_dzdy_numeric(8, i)); h_dzdx_numeric(8, i));
} }
for (int i = 0; i < 5; i++) { for (int i = 0; i < 5; i++) {
int idx = n_local - 1 - i; int idx = n_local - 1 - i;
printf("%d ra %f\n%d rn %f\n", world_rank, h_dzdy_actual(8, idx), printf("%d ra %f\n%d rn %f\n", world_rank, h_dzdx_actual(8, idx),
world_rank, h_dzdy_numeric(8, idx)); world_rank, h_dzdx_numeric(8, idx));
} }
*/ */
double err_norm = std::sqrt(gt::sum_squares(h_dzdy_numeric - h_dzdy_actual)); double err_norm = std::sqrt(gt::sum_squares(h_dzdx_numeric - h_dzdx_actual));
printf("%d/%d [%d:0x%08x] err_norm = %.8f\n", world_rank, world_size, printf("%d/%d [%d:0x%08x] err_norm = %.8f\n", world_rank, world_size,
device_id, vendor_id, err_norm); device_id, vendor_id, err_norm);