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sgemm_tcore: Double-buffer over K-dimension

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TODO: Not completely parameterized with DOUBLE_BUFFER yet.
This commit is contained in:
Hansung Kim
2024-06-04 18:23:27 -07:00
parent 18e3653d31
commit d8944db369
2 changed files with 155 additions and 92 deletions
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241
tests/regression/sgemm_tcore/kernel.cpp
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@@ -15,6 +15,8 @@
#define BK_LOOP 1
#define TRANSPOSE_AS 1
#define DOUBLE_BUFFER 1
// Constraints on parameters:
// * Memory:
// (BM + BN) * BK * sizeof(float) <= sharedmem size.
@@ -29,7 +31,7 @@
// BM <= BK*TM*TN
#define BM 32
#define BN 32
#define BK 32
#define BK 8
#define WM 16
#define WN 8
#define TCM 8
@@ -44,7 +46,12 @@
#define TM 1
#define TN 1
#endif
#define ELEM_PER_THREAD (WMITER * WNITER * TM * TN)
#define ELEM_PER_THREAD (WMITER * WNITER * TM * TN / (DOUBLE_BUFFER ? 2 : 1))
// FIXME: NUM_THREADS and NUM_WARPS hardcoded
#if ((BM * BN / ELEM_PER_THREAD) > (CORES_PER_CLUSTER * 8 * 8))
#error "threadblock size too big for cluster"
#endif
inline constexpr void map_operand_32lanes(const int tid, int &row, int &col) {
const int tg = tid / 4;
@@ -156,8 +163,6 @@ inline void vx_wmma_load_a(volatile float *smem_A, const int local_k,
constexpr int smem_A_cols = BK;
constexpr int smem_AS_rows = BK;
constexpr int smem_AS_cols = BM;
constexpr int smem_B_rows = BK;
constexpr int smem_B_cols = BN;
if constexpr (!TRANSPOSE_AS) {
int A_offset = (WM * warp_row + TCM * wm_iter + row) * smem_A_cols;
@@ -201,10 +206,6 @@ inline void vx_wmma_load_b(volatile float *smem_B, const int local_k,
int col = 0;
map_operand(tid, row, col);
constexpr int smem_A_rows = BM;
constexpr int smem_A_cols = BK;
constexpr int smem_AS_rows = BK;
constexpr int smem_AS_cols = BM;
constexpr int smem_B_rows = BK;
constexpr int smem_B_cols = BN;
@@ -294,11 +295,21 @@ inline void threadblock_barrier(unsigned int tid_in_threadblock,
inline void
global_dmem_load(const uint32_t dim_n, const uint32_t dim_k, const uint32_t k,
const float *A, const float *B, volatile float *local_a,
volatile float *local_b, const uint32_t threadblock_id_x,
const uint32_t threadblock_id_y, const uint32_t local_a_row,
const uint32_t local_a_col, const uint32_t local_as_row,
const uint32_t local_as_col, const uint32_t local_b_row,
const uint32_t local_b_col) {
volatile float *local_b, const uint32_t tid_in_threadblock,
const uint32_t threadblock_id_x,
const uint32_t threadblock_id_y) {
constexpr uint32_t BM_d = BM;
constexpr uint32_t BN_d = BN;
const uint32_t local_a_row = tid_in_threadblock / BK;
const uint32_t local_a_col = tid_in_threadblock % BK;
const uint32_t local_as_row = tid_in_threadblock / BM;
const uint32_t local_as_col = tid_in_threadblock % BM;
const uint32_t local_b_row = tid_in_threadblock / BN;
const uint32_t local_b_col = tid_in_threadblock % BN;
constexpr uint32_t threads_in_warpgroup =
(BM * BN) / ELEM_PER_THREAD / (DOUBLE_BUFFER ? 2 : 1); // FIXME
// Data move from GMEM to SMEM
//
@@ -307,24 +318,24 @@ global_dmem_load(const uint32_t dim_n, const uint32_t dim_k, const uint32_t k,
//
// TODO: Sharedmem swizzling is important here
if constexpr (!TRANSPOSE_AS) {
const uint32_t global_a_row = BM * threadblock_id_y + local_a_row;
const uint32_t global_a_row = BM_d * threadblock_id_y + local_a_row;
// number of rows a full TB can read at a time
constexpr uint32_t row_stride_a = (BM * BN) / ELEM_PER_THREAD / BK;
constexpr uint32_t row_stride_a = threads_in_warpgroup / BK;
#pragma GCC unroll 1
for (uint32_t local_row_offset = 0; local_row_offset < BM;
for (uint32_t local_row_offset = 0; local_row_offset < BM_d;
local_row_offset += row_stride_a) {
const uint32_t global_a_offset =
dim_k * (global_a_row + local_row_offset) + (k + local_a_col);
// NOTE: all threads in TB will do this load; make sure this is not
// out-of-bounds of BM*BK
// out-of-bounds of BM_d*BK
local_a[BK * (local_a_row + local_row_offset) + local_a_col] =
A[global_a_offset];
}
} else {
const uint32_t global_a_row = BM * threadblock_id_y + local_as_col;
// const uint32_t global_a_row = BM * threadblock_id_y + local_as_row;
constexpr uint32_t row_stride_as = (BM * BN) / ELEM_PER_THREAD / BM;
#pragma GCC unroll 1
const uint32_t global_a_row = BM_d * threadblock_id_y + local_as_col;
// const uint32_t global_a_row = BM_d * threadblock_id_y + local_as_row;
constexpr uint32_t row_stride_as = threads_in_warpgroup / BM_d;
#pragma GCC unroll 4
for (uint32_t local_row_offset = 0; local_row_offset < BK;
local_row_offset += row_stride_as) {
// @perf: bank conflicts here
@@ -333,25 +344,26 @@ global_dmem_load(const uint32_t dim_n, const uint32_t dim_k, const uint32_t k,
// FIXME experimenting with global coalescing
// const uint32_t global_a_offset =
// dim_k * (global_a_row + local_row_offset) + (k + local_as_col);
local_a[BM * (local_as_row + local_row_offset) + local_as_col] =
local_a[BM_d * (local_as_row + local_row_offset) + local_as_col] =
A[global_a_offset];
}
}
constexpr uint32_t row_stride_b = (BM * BN) / ELEM_PER_THREAD / BN;
const uint32_t global_b_col = BN * threadblock_id_x + local_b_col;
#pragma GCC unroll 1
constexpr uint32_t row_stride_b = threads_in_warpgroup / BN_d;
const uint32_t global_b_col = BN_d * threadblock_id_x + local_b_col;
#pragma GCC unroll 2
for (uint32_t load_offset = 0; load_offset < BK;
load_offset += row_stride_b) {
const uint32_t global_b_offset =
dim_n * (k + local_b_row + load_offset) + global_b_col;
local_b[BN * (local_b_row + load_offset) + local_b_col] =
local_b[BN_d * (local_b_row + load_offset) + local_b_col] =
B[global_b_offset];
}
}
void thread_block_gemm(kernel_arg_t *__UNIFORM__ arg,
const uint32_t tid_in_threadblock,
const uint32_t threads_per_threadblock,
const uint32_t threadblock_dim_x,
const uint32_t threadblock_dim_y,
const uint32_t threadblock_id_x,
@@ -376,14 +388,20 @@ void thread_block_gemm(kernel_arg_t *__UNIFORM__ arg,
const uint32_t local_c_row = tid_in_threadblock / (BN / TN);
const uint32_t local_c_col = tid_in_threadblock % (BN / TN);
#if !USE_TENSOR_CORE
// each thread generates TM output element
float reg_c[TM * TN] = { 0.0f };
float reg_a[TM] = { 0.0f };
float reg_b[TN] = { 0.0f };
#endif
const uint32_t warp_in_threadblock = tid_in_threadblock / NUM_LANES;
const uint32_t warp_row = warp_in_threadblock / (BN / WN);
const uint32_t warp_col = warp_in_threadblock % (BN / WN);
const uint32_t threads_per_warpgroup = threads_per_threadblock / (DOUBLE_BUFFER ? 2 : 1);
const uint32_t warpgroup_id = tid_in_threadblock / threads_per_warpgroup;
const uint32_t tid_in_warpgroup = tid_in_threadblock % threads_per_warpgroup; // FIXME
const uint32_t warp_in_warpgroup = tid_in_warpgroup / NUM_LANES;
// FIXME: warp_row / BN should be warp-specialized?
const uint32_t warp_row = warp_in_warpgroup / (BN / WN);
const uint32_t warp_col = warp_in_warpgroup % (BN / WN);
const uint32_t tid_in_warp = tid_in_threadblock % NUM_LANES;
volatile float *local_a = sharedmem_per_threadblock;
@@ -391,69 +409,109 @@ void thread_block_gemm(kernel_arg_t *__UNIFORM__ arg,
const size_t local_a_elems = (BM * BK);
volatile float *local_b = sharedmem_per_threadblock + local_a_elems;
const size_t local_b_elems = (BK * BN);
volatile float *local_a_buf = local_b + local_b_elems;
volatile float *local_b_buf = local_a_buf + local_a_elems;
volatile float *local_warp_results =
local_b + local_b_elems + (warp_in_threadblock * TCM * TCN);
local_b_buf + local_b_elems + (warp_in_warpgroup * TCM * TCN);
// clear out C
initialize_C(0);
initialize_C(1);
#pragma GCC unroll 1
for (uint32_t k = 0; k < dim_k; k += BK) {
global_dmem_load(dim_n, dim_k, k, A, B, local_a, local_b,
threadblock_id_x, threadblock_id_y, local_a_row,
local_a_col, local_as_row, local_as_col, local_b_row,
local_b_col);
threadblock_barrier(tid_in_threadblock, threadblock_id_in_cluster,
threadblock_dim_y);
#if USE_TENSOR_CORE
// @perf: this loop spills to stack a lot because of all the flws in
// vx_wmma_load
#pragma GCC unroll 1
for (int i = 0; i < BK_LOOP; i++) {
#pragma GCC unroll 1
for (uint32_t local_k = 0; local_k < BK; local_k += TCK) {
// perform wmma
// vx_wmma_load(local_a, local_b, warp_x, warp_y, tid_in_warp);
// FIXME: this is wrong!! need separate accumulation register for
// WM/WN_ITERS
#pragma GCC unroll 2
for (int wn_iter = 0; wn_iter < WNITER; wn_iter++) {
vx_wmma_load_b(local_b, local_k, warp_col, wn_iter, tid_in_warp);
// vx_wmma_load_b(local_b, 0, 0, 0, tid_in_warp);
#pragma GCC unroll 2
for (int wm_iter = 0; wm_iter < WMITER; wm_iter++) {
#if TC_SINGLE_WARP
if (warp_in_threadblock == 0) {
#endif
// if ((threadblock_id_in_cluster % 2) == 0) {
// asm volatile("addi a0, a0, 0");
// asm volatile("addi a0, a0, 0");
// asm volatile("addi a0, a0, 0");
// asm volatile("addi a0, a0, 0");
// asm volatile("addi a0, a0, 0");
// asm volatile("addi a0, a0, 0");
// asm volatile("addi a0, a0, 0");
// asm volatile("addi a0, a0, 0");
// asm volatile("addi a0, a0, 0");
// }
// SMEM -> RF
vx_wmma_load_a(local_a, local_k, warp_row, wm_iter, tid_in_warp);
// vx_wmma_load_a(local_a, 0, 0, 0, tid_in_warp);
// compute
vx_wmma(wm_iter);
#if TC_SINGLE_WARP
}
#endif
}
}
}
if constexpr (DOUBLE_BUFFER) {
// initiate software pipeline
if (warpgroup_id == 0) {
global_dmem_load(dim_n, dim_k, 0 /*k*/, A, B, local_a, local_b,
tid_in_warpgroup, threadblock_id_x, threadblock_id_y);
}
threadblock_barrier(tid_in_threadblock, threadblock_id_in_cluster,
threadblock_dim_y);
}
uint32_t k_index = 0;
#pragma GCC unroll 1
for (uint32_t k = 0; k < dim_k; k += BK) {
volatile float *local_a_produce;
volatile float *local_b_produce;
volatile float *local_a_consume;
volatile float *local_b_consume;
if constexpr (DOUBLE_BUFFER) {
local_a_produce = (k_index % 2) ? local_a : local_a_buf;
local_b_produce = (k_index % 2) ? local_b : local_b_buf;
local_a_consume = (k_index % 2) ? local_a_buf : local_a;
local_b_consume = (k_index % 2) ? local_b_buf : local_b;
} else {
local_a_produce = local_a;
local_b_produce = local_b;
local_a_consume = local_a;
local_b_consume = local_b;
}
k_index++;
if (warpgroup_id == 0) {
if (k != (dim_k - BK)) {
global_dmem_load(dim_n, dim_k, k + BK /*runahead*/, A, B,
local_a_produce, local_b_produce, tid_in_warpgroup,
threadblock_id_x, threadblock_id_y);
}
threadblock_barrier(tid_in_threadblock, threadblock_id_in_cluster,
threadblock_dim_y);
}
else {
#if USE_TENSOR_CORE
// @perf: this loop spills to stack a lot because of all the flws in
// vx_wmma_load
#pragma GCC unroll 1
for (int i = 0; i < BK_LOOP; i++) {
#pragma GCC unroll 1
for (uint32_t local_k = 0; local_k < BK; local_k += TCK) {
// perform wmma
// vx_wmma_load(local_a_consume, local_b_consume, warp_x, warp_y, tid_in_warp);
// FIXME: this is wrong!! need separate accumulation register for
// WM/WN_ITERS
#pragma GCC unroll 2
for (int wn_iter = 0; wn_iter < WNITER; wn_iter++) {
vx_wmma_load_b(local_b_consume, local_k, warp_col, wn_iter, tid_in_warp);
// vx_wmma_load_b(local_b_consume, 0, 0, 0, tid_in_warp);
#pragma GCC unroll 1
for (int wm_iter = 0; wm_iter < WMITER; wm_iter++) {
#if TC_SINGLE_WARP
if (warp_in_warpgroup == 0) {
#endif
// if ((threadblock_id_in_cluster % 2) == 0) {
// asm volatile("addi a0, a0, 0");
// asm volatile("addi a0, a0, 0");
// asm volatile("addi a0, a0, 0");
// asm volatile("addi a0, a0, 0");
// asm volatile("addi a0, a0, 0");
// asm volatile("addi a0, a0, 0");
// asm volatile("addi a0, a0, 0");
// asm volatile("addi a0, a0, 0");
// asm volatile("addi a0, a0, 0");
// }
// SMEM -> RF
vx_wmma_load_a(local_a_consume, local_k, warp_row, wm_iter,
tid_in_warp);
// vx_wmma_load_a(local_a_consume, 0, 0, 0, tid_in_warp);
// compute
vx_wmma(wm_iter);
#if TC_SINGLE_WARP
}
#endif
}
}
}
}
threadblock_barrier(tid_in_threadblock, threadblock_id_in_cluster,
threadblock_dim_y);
}
#else
@@ -498,11 +556,13 @@ void thread_block_gemm(kernel_arg_t *__UNIFORM__ arg,
#pragma GCC unroll 1
for (int wn_iter = 0; wn_iter < WNITER; wn_iter++) {
#if TC_SINGLE_WARP
if (warp_in_threadblock == 0) {
if (warp_in_warpgroup == 0) {
#endif
write_results(local_warp_results, tid_in_warp, warp_col, warp_row,
wn_iter, wm_iter, dim_m, dim_n, C, threadblock_id_x,
threadblock_id_y);
if (warpgroup_id == 1) {
write_results(local_warp_results, tid_in_warp, warp_col, warp_row,
wn_iter, wm_iter, dim_m, dim_n, C, threadblock_id_x,
threadblock_id_y);
}
#if TC_SINGLE_WARP
}
#endif
@@ -554,9 +614,12 @@ void kernel_body(int task_id, kernel_arg_t *__UNIFORM__ arg) {
// occupancy of a single cluster
float *sharedmem_per_threadblock =
(float *)DEV_SMEM_START_ADDR + (2 * BM * BK) * threadblock_id_in_cluster;
thread_block_gemm(arg, tid_in_threadblock, threadblock_dim_x,
threadblock_dim_y, threadblock_id_x, threadblock_id_y,
threadblock_id_in_cluster, sharedmem_per_threadblock);
const int warp_id = vx_warp_id();
thread_block_gemm(arg, tid_in_threadblock, threads_per_threadblock,
threadblock_dim_x, threadblock_dim_y, threadblock_id_x,
threadblock_id_y, threadblock_id_in_cluster,
sharedmem_per_threadblock);
}
int main() {

6
tests/regression/sgemm_tcore/main.cpp
View File

@@ -155,9 +155,9 @@ int main(int argc, char *argv[]) {
RT_CHECK(vx_dev_open(&device));
// FIXME: hardcoded
uint32_t dim_m = 16;
uint32_t dim_n = 16;
uint32_t dim_k = 16;
uint32_t dim_m = 32;
uint32_t dim_n = 32;
uint32_t dim_k = 32;
generate_source_matrix(dim_m, dim_n, dim_k);
generate_reference_matmul(dim_m, dim_n, dim_k);