193 lines
7.6 KiB
C++
193 lines
7.6 KiB
C++
#include <stdint.h>
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#include <vx_intrinsics.h>
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#include <vx_print.h>
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#include <vx_spawn.h>
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#include "common.h"
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// Constraints on parameters:
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// * Memory:
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// (BM + BN) * BK * sizeof(float) <= sharedmem size.
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// BM * BK == BN * BK >= threadblock size >= NT * CORES_PER_CLUSTER
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// When larger, the kernel runs a sequential loop to read into sharedmem;
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// but smaller case is not handled.
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// * Compute:
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// ( M* N) / (TM*TN) == grid size >= NC*NW*NT
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// (BM*BN) / (TM*TN) == threadblock size < NT * NW * CORES_PER_CLUSTER
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// (BM*BN) / (TM*TN) == threadblock size >= NT * CORES_PER_CLUSTER
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// * Combining BM * BK >= (BM*BN) / (TM*TN) == threadblock yields
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// BM <= BK*TM*TN
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#define BM 32
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#define BN BM
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#define BK 8
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#define TM 4
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#define TN 4
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void threadblock_barrier(unsigned int tid_in_threadblock, unsigned int barrier_id, unsigned int count) {
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vx_fence();
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vx_barrier(barrier_id, count);
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}
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void thread_block_gemm(kernel_arg_t *__UNIFORM__ arg,
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const uint32_t tid_in_threadblock,
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const uint32_t threadblock_dim_x,
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const uint32_t threadblock_dim_y,
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const uint32_t threadblock_id_x,
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const uint32_t threadblock_id_y,
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const uint32_t threadblock_id_in_cluster,
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float *sharedmem_per_threadblock) {
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const float *A = (const float *)arg->addr_a;
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const float *B = (const float *)arg->addr_b;
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float *C = (float *)arg->addr_c;
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// assumes NT == NW == matrix_dim
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const uint32_t dim_m = arg->dim_m;
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const uint32_t dim_n = arg->dim_n;
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const uint32_t dim_k = arg->dim_k;
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// FIXME: Output block size is assumed to be square, i.e. BM == BN
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// const uint32_t BM = threadblock_dim_y;
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// const uint32_t BN = threadblock_dim_y;
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// const uint32_t BK = threadblock_dim_x;
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// constexpr uint32_t BM = 8;
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// constexpr uint32_t BN = 8;
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// constexpr uint32_t BK = 2;
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const uint32_t local_a_row = tid_in_threadblock / BK;
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const uint32_t local_a_col = tid_in_threadblock % BK;
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const uint32_t local_b_row = tid_in_threadblock / BN;
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const uint32_t local_b_col = tid_in_threadblock % BN;
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const uint32_t global_a_row = BM * threadblock_id_y + local_a_row;
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const uint32_t global_b_col = BN * threadblock_id_x + local_b_col;
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const uint32_t local_c_row = tid_in_threadblock / (BN / TN);
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const uint32_t local_c_col = tid_in_threadblock % (BN / TN);
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// each thread generates TM output element
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float reg_c[TM * TN] = { 0.0f };
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float reg_a[TM] = { 0.0f };
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float reg_b[TN] = { 0.0f };
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volatile float *local_a = sharedmem_per_threadblock;
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// const size_t local_a_elems = threadblock_dim_x * threadblock_dim_y;
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const size_t local_a_elems = (BM * BK);
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volatile float *local_b = sharedmem_per_threadblock + local_a_elems;
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constexpr uint32_t stride_a = (BM * BN) / BK / (TM * TN);
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constexpr uint32_t stride_b = (BM * BN) / BN / (TM * TN);
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for (uint32_t k = 0; k < dim_k; k += BK) {
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// Data move from GMEM to SMEM
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//
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// Make sure global offset values for A and B are contiguous between
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// neighboring threads to ensure GMEM coalescing.
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#pragma GCC unroll 2
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for (uint32_t load_offset = 0; load_offset < BM; load_offset += stride_a) {
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const uint32_t global_a_offset =
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dim_k * (global_a_row + load_offset) + (k + local_a_col);
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local_a[BK * (local_a_row + load_offset) + local_a_col] =
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A[global_a_offset];
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}
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#pragma GCC unroll 2
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for (uint32_t load_offset = 0; load_offset < BK; load_offset += stride_b) {
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const uint32_t global_b_offset =
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dim_n * (k + local_b_row + load_offset) + global_b_col;
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local_b[BN * (local_b_row + load_offset) + local_b_col] =
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B[global_b_offset];
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}
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threadblock_barrier(tid_in_threadblock, threadblock_id_in_cluster,
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threadblock_dim_y);
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// Compute single tile*tile matmul
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#pragma GCC unroll 4
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for (uint32_t local_k = 0; local_k < BK; local_k++) {
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// First, pump data from SMEM->RF
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#pragma GCC unroll TM
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for (uint32_t res_idx_m = 0; res_idx_m < TM; res_idx_m++) {
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reg_a[res_idx_m] =
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local_a[BK * (TM * local_c_row + res_idx_m) + local_k];
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}
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#pragma GCC unroll TN
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for (uint32_t res_idx_n = 0; res_idx_n < TN; res_idx_n++) {
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reg_b[res_idx_n] =
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local_b[BN * local_k + (TN * local_c_col + res_idx_n)];
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}
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// Next, compute multiple result elements (TM*TN) by reusing data in RF
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#pragma GCC unroll TM
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for (uint32_t res_idx_m = 0; res_idx_m < TM; res_idx_m++) {
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#pragma GCC unroll TN
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for (uint32_t res_idx_n = 0; res_idx_n < TN; res_idx_n++) {
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// NOTE use of local_b_row
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reg_c[TN * res_idx_m + res_idx_n] +=
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reg_a[res_idx_m] * reg_b[res_idx_n];
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// reg_c[TN * res_idx_m + res_idx_n] +=
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// local_a[BK * (TM * local_c_row + res_idx_m) + local_k] *
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// local_b[BN * local_k + (TN * local_c_col + res_idx_n)];
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}
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}
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}
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threadblock_barrier(tid_in_threadblock, threadblock_id_in_cluster,
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threadblock_dim_y);
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}
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// Store result data from RF to GMEM
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#pragma GCC unroll TM
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for (uint32_t res_idx_m = 0; res_idx_m < TM; res_idx_m++) {
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#pragma GCC unroll TN
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for (uint32_t res_idx_n = 0; res_idx_n < TN; res_idx_n++) {
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C[dim_n * (BM * threadblock_id_y + TM * local_c_row + res_idx_m) +
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(BN * threadblock_id_x + TN * local_c_col + res_idx_n)] =
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reg_c[TN * res_idx_m + res_idx_n];
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}
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}
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}
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void kernel_body(int task_id, kernel_arg_t *__UNIFORM__ arg) {
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// @perf: All threads are running these compute whose result is mostly same
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// across the threadblock
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const uint32_t threads_per_threadblock = (BM * BN) / (TM * TN);
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#ifdef RADIANCE
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const uint32_t threadblocks_per_core = vx_num_threads() * vx_num_warps() /
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threads_per_threadblock *
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CORES_PER_CLUSTER;
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#else
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const uint32_t threadblocks_per_core =
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vx_num_threads() * vx_num_warps() / threads_per_threadblock;
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#endif
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const uint32_t threadblock_dim_x = vx_num_threads();
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const uint32_t threadblock_dim_y = vx_num_warps() / threadblocks_per_core;
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const int threadblock_id = task_id / threads_per_threadblock;
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const int threadblock_id_in_cluster = threadblock_id % threadblocks_per_core;
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const int tid_in_threadblock = task_id % threads_per_threadblock;
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const uint32_t dim_m = arg->dim_m;
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const uint32_t dim_n = arg->dim_n;
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const uint32_t dim_n_in_blocks = dim_n / BN;
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const int threadblock_id_x = threadblock_id % dim_n_in_blocks;
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const int threadblock_id_y = threadblock_id / dim_n_in_blocks;
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// "static" shared memory allocation. This would determine threadblock
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// occupancy of a single cluster
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float *sharedmem_per_threadblock =
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(float *)DEV_SMEM_START_ADDR + (2 * BM * BK) * threadblock_id_in_cluster;
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thread_block_gemm(arg, tid_in_threadblock, threadblock_dim_x,
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threadblock_dim_y, threadblock_id_x, threadblock_id_y,
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threadblock_id_in_cluster, sharedmem_per_threadblock);
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}
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int main() {
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kernel_arg_t *arg = (kernel_arg_t *)KERNEL_ARG_DEV_MEM_ADDR;
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const uint32_t grid_size = arg->dim_m * arg->dim_n / (TM * TN);
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#ifdef RADIANCE
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vx_spawn_tasks_cluster(grid_size, (vx_spawn_tasks_cb)kernel_body, arg);
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#else
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// NOTE: This kernel assumes contiguous thread scheduling for efficient shared
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// memory allocation, and therefore does not work with original vx_spawn_tasks
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vx_spawn_tasks_contiguous(grid_size, (vx_spawn_tasks_cb)kernel_body, arg);
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#endif
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return 0;
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}
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