Batched GEMM¶

Exercises the LIBXS batched GEMM API (libxs_gemm.h) in several flavors: strided, pointer-array, indexed, and grouped. All programs are multithreaded via OpenMP, report wall-clock time and GFLOPS/s, and optionally validate results via libxs_matdiff.

Building¶

cd samples/gemm
make GNU=1

LIBXS must be built first from the repository root.

Programs¶

gemm_strided¶

Strided batch DGEMM: all matrices packed contiguously with constant stride. Uses libxs_gemm_index with index_stride=0.

./gemm_strided.x [M [N [K [batchsize [nrepeat [beta [pad]]]]]]]

Defaults: M=N=K=23, batchsize=30000, nrepeat=3, beta=1.0, pad=0.

gemm_batch¶

Pointer-array batch DGEMM: matrices accessed through pointer arrays. Supports a duplicate C-matrix mode to exercise lock-forward sync.

./gemm_batch.x [M [N [K [batchsize [nrepeat [dup [beta [pad]]]]]]]]

Defaults: M=N=K=23, batchsize=30000, nrepeat=3, dup=0, beta=1.0, pad=0.

dup	Mode	Description
0	None	Each C-matrix is unique (LIBXS_GEMM_FLAG_NOLOCK)
1	Sorted	Half-unique C-pointers, duplicates consecutive
2	Shuffled	Half-unique C-pointers, randomly shuffled

gemm_index¶

Index-array batch DGEMM: matrices in contiguous buffers, addressed through explicit element-offset index arrays (ia, ib, ic).

./gemm_index.x [M [N [K [batchsize [nrepeat [beta [pad]]]]]]]

Defaults: M=N=K=23, batchsize=30000, nrepeat=3, beta=1.0, pad=0.

gemm_indexf¶

Fortran variant of gemm_index. Demonstrates the LIBXS Fortran module interface with one-based index arrays and C_LOC/C_SIZEOF interop. Requires a Fortran compiler.

./gemm_indexf.x [M [N [K [batchsize [nrepeat]]]]]

Defaults: M=N=K=23, batchsize=30000, nrepeat=3.

gemm_groups¶

Grouped batch DGEMM: multiple groups of different matrix shapes dispatched in sequence, each with its own libxs_gemm_config_t. Per-group dimensions grow by 4 starting from base_m.

./gemm_groups.x [ngroups [batch_per_group [nrepeat [base_m [beta [pad]]]]]]

Defaults: ngroups=2 (max 4), batch_per_group=30000, nrepeat=3, base_m=8, beta=1.0, pad=0.

Validation¶

Set the CHECK environment variable to validate results:

CHECK=1 ./gemm_strided.x
CHECK=1 ./gemm_batch.x 23 23 23 1000 1 2
CHECK=1 ./gemm_index.x
CHECK=1 ./gemm_groups.x

When padding is enabled (pad>0), the check also verifies that leading-dimension padding in C-matrices has not been overwritten.

Runtime Controls¶

Set LIBXS_GEMM_PRINT=0 to print a compact GEMM registry summary at termination. The first line reports registry size, capacity, memory, and the selected LIBXS_GEMM_BACKEND policy; the second line reports a histogram by datatype and backend.