More probing why test harness vs. slate was a little faster running Grid's dense inverse than normal environment

This commit is contained in:
Peter Boyle
2026-08-27 13:42:18 -04:00
parent 68b9fa86d7
commit 6cea81bc2c
4 changed files with 171 additions and 0 deletions
+4
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@@ -114,15 +114,18 @@ public:
// NB: written to rocSOLVER's documented z*_64 signatures; not compiled on
// HIP in the air-gapped loop -- verify on first hipcc build.
///////////////////////////////////////////////////////////////////////////
double lastGetrfUs = 0.0, lastGetrsUs = 0.0; // split timing of the last inverseLU (HIP path)
void inverseLU(int64_t N, ComplexD *A)
{
#ifdef GRID_HIP
rocblas_handle handle = Handle();
deviceVector<int64_t> ipiv((uint64_t)N);
deviceVector<int64_t> info(1);
double t0 = usecond();
auto st1 = rocsolver_zgetrf_64(handle, N, N, (rocblas_double_complex *)A, N, &ipiv[0], &info[0]);
GRID_ASSERT(st1 == rocblas_status_success);
accelerator_barrier();
lastGetrfUs = usecond()-t0;
int64_t info_h = -1; acceleratorCopyFromDevice(&info[0], &info_h, sizeof(int64_t));
GRID_ASSERT(info_h == 0);
deviceVector<ComplexD> X((uint64_t)N*N);
@@ -134,6 +137,7 @@ public:
(rocblas_double_complex *)&X[0], N);
GRID_ASSERT(st2 == rocblas_status_success);
accelerator_barrier();
lastGetrsUs = usecond()-t0-lastGetrfUs;
acceleratorCopyDeviceToDevice((void *)&X[0], (void *)A, (uint64_t)N*N*sizeof(ComplexD));
#else
deviceVector<ComplexD*> bp(1); std::vector<ComplexD*> ptr(1); ptr[0] = A;
@@ -439,6 +439,50 @@ public:
}
}
///////////////////////////////////////////////////////////////////////
// ONE-GCD LEAF MICROBENCHMARK (boss only). The big-leaf inverse at
// W=4320 measured 0.53 s with BOTH getri_batched and getrf_64+getrs_64
// (2026-08-27) -- ~0.4 TF/s on a GCD that runs zgemm at ~15. Time the
// three primitives in isolation on a well-conditioned dense matrix so the
// leaf's rate can be compared with the machine's, and getrf split from
// getrs. Sizes: the W of span 4 / 9 / 18 leaves on accelerator builds;
// tiny on CPU builds (Eigen would take minutes at 4320).
///////////////////////////////////////////////////////////////////////
if ( me == 0 ) {
#if defined(GRID_HIP) || defined(GRID_CUDA) || defined(GRID_SYCL)
std::vector<int64_t> Ws({1920, 4320, 8640});
#else
std::vector<int64_t> Ws({240, 480});
#endif
for(int64_t W : Ws){
deviceVector<ComplexD> M((uint64_t)W*W), C((uint64_t)W*W);
{ ComplexD *m = &M[0]; const int64_t WW = W; // diagonally dominant: (i==j ? W : 0) + cos/sin noise
accelerator_for(idx,(uint64_t)W*W,1,{ int64_t j=idx/WW, i=idx-j*WW; double x=0.37*i+0.61*j;
m[idx] = ComplexD((i==j)?(double)WW:0.0,0.0) + ComplexD(std::cos(x),std::sin(1.3*x)); });
accelerator_barrier(); }
double flopLU = 8.0/3.0*(double)W*W*W; // complex LU ~ (4 real flops per complex mult-add) * (2/3 n^3)
double flopGEMM = 8.0*(double)W*W*W; // complex GEMM
// 1. getri_batched (batch 1)
double tb;
{ deviceVector<ComplexD*> bp(1); std::vector<ComplexD*> ptr(1); ptr[0]=&M[0];
acceleratorCopyToDevice(&ptr[0],&bp[0],sizeof(ComplexD*));
double t0=usecond(); INV.inverseBatched(W,bp); tb=usecond()-t0; }
// 2. inverseLU (getrf_64 + identity getrs_64), timed inside
double tl; { double t0=usecond(); INV.inverseLU(W,&M[0]); tl=usecond()-t0; }
// 3. one zgemm W x W x W for the machine rate
double tg;
{ deviceVector<ComplexD*> ap(1),bp(1),cp(1); std::vector<ComplexD*> ptr(1);
ptr[0]=&M[0]; acceleratorCopyToDevice(&ptr[0],&ap[0],sizeof(ComplexD*)); acceleratorCopyToDevice(&ptr[0],&bp[0],sizeof(ComplexD*));
ptr[0]=&C[0]; acceleratorCopyToDevice(&ptr[0],&cp[0],sizeof(ComplexD*));
double t0=usecond();
SUMMA.BLAS.gemmBatched(GridBLAS_OP_N,GridBLAS_OP_N,(int)W,(int)W,(int)W,ComplexD(1.0,0.0),ap,(int)W,bp,(int)W,ComplexD(0.0,0.0),cp,(int)W);
SUMMA.BLAS.synchronise(); tg=usecond()-t0; }
std::cout << GridLogMessage << "Schur2D PROBE leaf W=" << W
<< ": getri_batched " << tb/1.0e6 << " s (" << flopLU/tb/1.0e6 << " TF/s)"
<< " getrf_64+getrs_64 " << tl/1.0e6 << " s (getrf " << INV.lastGetrfUs/1.0e6 << " getrs " << INV.lastGetrsUs/1.0e6 << ")"
<< " zgemm " << tg/1.0e6 << " s (" << flopGEMM/tg/1.0e6 << " TF/s)" << std::endl;
}
}
///////////////////////////////////////////////////////////////////////
// The SUMMA's conditions, one at a time, at 8 MB on ring B:
// (a) LARGE persistent buffers (the rings use ~0.5 GB Abuf/Bbuf), sending
// from offset 0 and from deep inside the region;
+91
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@@ -0,0 +1,91 @@
#!/bin/bash -l
#SBATCH --job-name=schur2d-env
#SBATCH --nodes=36
#SBATCH --ntasks-per-node=8
#SBATCH --cpus-per-task=7
#SBATCH --gpus-per-node=8
#SBATCH --time=0:40:00
#SBATCH --account=phy157_dwf
#SBATCH --gpu-bind=none
#SBATCH --exclusive
#SBATCH --mem=0
#SBATCH -S 0
##############################################################################
# Environment walk for the 2D Schur inverse (2026-08-27).
#
# The SAME inverse (N=138240, 18x16, nb 480, SCHUR2D_LEAF_SPAN=9, LU leaf)
# runs 20.8 s in Test_schur2d_vs_slate and 26.5 s in the production example,
# and the LOCAL GPU work is what differs: GEMM 2.47 vs 3.11 s, leaf inverse
# 0.53 vs 0.76 s for identical calls; rings about equal. The environments
# differ in (a) OMP_NUM_THREADS 1 vs 7, (b) MPI_THREAD_MULTIPLE init (SLATE
# harness) vs SERIALIZED (example), (c) ~10.6 GB of fine-grid state resident
# on the device in the example. Test_schur2d_scale is the SLATE-free harness
# (same library code, plain Grid_init); walk it from the harness environment
# to the example's one knob at a time.
#
# Readout per cell (identical work in every cell):
# "gemm min/max" vs 2.45/2.61 (harness) / 3.01/3.24 (example)
# "BIG LEAVES ... inverse (max over ranks)" vs 0.53 / 0.76
# "SCHUR fp64 ... invert" / "GRID : ... invert" vs 20.8 / 26.5
# "Schur2D PROBE leaf W=" one-GCD getri / getrf+getrs / zgemm TF/s
##############################################################################
cat << EOF > select_gpu
#!/bin/bash
export GPU_MAP=(0 1 2 3 7 6 5 4)
export NUMA_MAP=(3 3 1 1 2 2 0 0)
export GPU=\${GPU_MAP[\$SLURM_LOCALID]}
export NUMA=\${NUMA_MAP[\$SLURM_LOCALID]}
export HIP_VISIBLE_DEVICES=\$GPU
unset ROCR_VISIBLE_DEVICES
if [ \$SLURM_PROCID = "0" ]; then echo \$*; fi
exec numactl -m \$NUMA -N \$NUMA \$*
EOF
chmod +x ./select_gpu
root=$HOME/ParallelIO/systems/Frontier
source $root/sourceme-rocm7.2.sh
export MPICH_GPU_SUPPORT_ENABLED=1
export MPICH_SMP_SINGLE_COPY_MODE=CMA
export MPICH_OFI_NIC_POLICY=GPU
module load libfabric
BIN=$root/tests/debug/Test_schur2d_scale
OPTS1="--accelerator-threads 8 --shm 4096 --shm-mpi 1 --device-mem 32000"
vol=48.48.48.96
MPI_GEOM=3.6.4.4
export S2D_N=138240
export S2D_NB=480
export SCHUR2D_LEAF_SPAN=9
export SCHUR2D_LEAF_LU=1
export SUMMA_HANDSHAKE=1
# SCHUR2D_PROBE unset: probe on, including the one-GCD leaf microbenchmark
run_cell () {
name=$1; shift
echo "----- $name : $* -----"
fname=log.env.$name
env "$@" srun -N36 -n288 --kill-on-bad-exit=1 ./select_gpu $BIN --mpi ${MPI_GEOM} --grid $vol $OPTS1 > $fname 2>&1
echo " exit $?"; sleep 30
grep -h "PROBE banner\|device ballast\|PROBE leaf\|BIG LEAVES\|gemm min/max\|invert\|certificate" $fname \
| sed 's/^Grid : Message : [0-9.]* s : //' | cut -c1-170
}
# name environment
run_cell E1_omp1 OMP_NUM_THREADS=1
run_cell E2_omp1_multiple OMP_NUM_THREADS=1 GRID_MPI_THREAD_MULTIPLE=1 MPICH_MAX_THREAD_SAFETY=multiple # = the SLATE harness environment
run_cell E3_omp7 OMP_NUM_THREADS=7 # the example's thread count
run_cell E4_omp7_ballast OMP_NUM_THREADS=7 S2D_BALLAST_GB=10.6 # + the example's device residency
run_cell E5_omp1_ballast OMP_NUM_THREADS=1 S2D_BALLAST_GB=10.6 # ballast alone
run_cell E6_omp1_again OMP_NUM_THREADS=1 # repeat E1: the noise floor
echo "========================================================="
echo "summary"
for f in log.env.E*; do
echo "$f: $(grep -h "invert" $f | grep -h "TOTAL\|took" | sed 's/^Grid : Message : [0-9.]* s : //' | cut -c1-80 | head -1) gemm $(grep -oh "gemm min/max [0-9./]*" $f) leaf $(grep -oh "inverse (max over ranks) [0-9.]*" $f)"
done
echo "harness (SLATE build, OMP=1, MULTIPLE): invert 20.8 gemm 2.45/2.61 leaf 0.53; example (OMP=7, SERIALIZED, 10.6 GB resident): 26.5 3.01/3.24 0.76"
echo "========================================================="
+32
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@@ -76,6 +76,20 @@ static ComplexD Fill(int64_t i, int64_t j, int64_t N)
int main(int argc, char **argv)
{
// Environment walk (2026-08-27): the SAME inverse runs 20.8 s in the SLATE
// harness and 26.5 s in the example, with the local GPU work (GEMM, leaf
// inverse) 25-40% slower in the example. Knobs to reproduce the example's
// environment here, one at a time (systems/Frontier/schur2d_env.job):
// GRID_MPI_THREAD_MULTIPLE=1 MPI_Init_thread(MULTIPLE) before Grid_init (SLATE harness does this)
// S2D_BALLAST_GB=x x GB of Lattice fields made device-resident before the invert
// (the example carries ~10.6 GB of fine-grid state in the MemoryManager)
// OMP_NUM_THREADS set in the job, read by nothing here but the runtime
if ( getenv("GRID_MPI_THREAD_MULTIPLE") ) {
int provided = 0;
MPI_Init_thread(&argc, &argv, MPI_THREAD_MULTIPLE, &provided);
std::cout << "GRID_MPI_THREAD_MULTIPLE: requested MPI_THREAD_MULTIPLE, provided " << provided
<< (provided==MPI_THREAD_MULTIPLE ? " (MULTIPLE)" : " (NOT multiple)") << std::endl;
}
Grid_init(&argc, &argv);
GridCartesian *grid = SpaceTimeGrid::makeFourDimGrid(GridDefaultLatt(),
@@ -125,6 +139,24 @@ int main(int argc, char **argv)
BlockCyclicMatrix A0(grid,N,nb,Pr,Pc);
BlockCyclicSchurInverse RSI2;
// Device ballast: Lattice fields written on the accelerator so they sit in
// the MemoryManager's device LRU exactly as the example's fine-grid state does.
typedef Lattice<iVector<iVector<vComplexD,Nc>,Ns> > BallastField;
std::vector<BallastField> ballast;
if ( getenv("S2D_BALLAST_GB") ) {
double gb = atof(getenv("S2D_BALLAST_GB"));
uint64_t fbytes = (uint64_t)grid->oSites()*sizeof(BallastField::vector_object);
int nf = (int)(gb*1.0e9/(double)fbytes + 0.5);
ballast.reserve(nf);
for(int i=0;i<nf;i++){
ballast.emplace_back(grid);
autoView(v, ballast[i], AcceleratorWriteDiscard);
accelerator_for(ss, grid->oSites(), 1, { v[ss] = Zero(); });
}
std::cout << GridLogMessage << "Test_schur2d_scale: device ballast " << nf << " fields x " << fbytes/1.0e6
<< " MB = " << nf*fbytes/1.0e9 << " GB resident (S2D_BALLAST_GB=" << gb << ")" << std::endl;
}
BlockCyclicRedistribute::RowsToCyclic(grid,rowStart,&rows1d[0],myrows,A);
double t2 = usecond();
if ( A.data.size() )