llama.cpp/ggml/src/ggml-cuda/norm.cu
Johannes Gäßler 9c8dcefe17
CUDA: backwards pass for misc. ops, add tests (#11257)
* CUDA: backwards pass for misc. ops, add tests

* remove restrict from pointers
2025-01-16 16:43:38 +01:00

317 lines
10 KiB
Text

#include "norm.cuh"
template <int block_size>
static __global__ void norm_f32(const float * x, float * dst, const int ncols, const float eps) {
const int row = blockIdx.x*blockDim.y + threadIdx.y;
const int tid = threadIdx.x;
x += int64_t(row)*ncols;
dst += int64_t(row)*ncols;
float2 mean_var = make_float2(0.0f, 0.0f);
for (int col = tid; col < ncols; col += block_size) {
const float xi = x[col];
mean_var.x += xi;
mean_var.y += xi * xi;
}
// sum up partial sums
mean_var = warp_reduce_sum(mean_var);
if constexpr (block_size > WARP_SIZE) {
static_assert(block_size == 1024, "unexpected block_size");
__shared__ float2 s_sum[32];
const int warp_id = threadIdx.x / WARP_SIZE;
const int lane_id = threadIdx.x % WARP_SIZE;
if (lane_id == 0) {
s_sum[warp_id] = mean_var;
}
__syncthreads();
mean_var = s_sum[lane_id];
mean_var = warp_reduce_sum(mean_var);
}
const float mean = mean_var.x / ncols;
const float var = mean_var.y / ncols - mean * mean;
const float inv_std = rsqrtf(var + eps);
for (int col = tid; col < ncols; col += block_size) {
dst[col] = (x[col] - mean) * inv_std;
}
}
template <int block_size>
static __global__ void group_norm_f32(const float * x, float * dst, const int group_size, const int ne_elements, const float eps) {
// blockIdx.x: num_groups idx
// threadIdx.x: block_size idx
const int start = blockIdx.x*group_size + threadIdx.x;
const int end = min(blockIdx.x*group_size + group_size, ne_elements);
float tmp = 0.0f; // partial sum for thread in warp
for (int j = start; j < end; j += block_size) {
tmp += x[j];
}
tmp = warp_reduce_sum(tmp);
if constexpr (block_size > WARP_SIZE) {
static_assert(block_size == 1024, "unexpected block_size");
__shared__ float s_sum[32];
const int warp_id = threadIdx.x / WARP_SIZE;
const int lane_id = threadIdx.x % WARP_SIZE;
if (lane_id == 0) {
s_sum[warp_id] = tmp;
}
__syncthreads();
tmp = s_sum[lane_id];
tmp = warp_reduce_sum(tmp);
}
const float mean = tmp / group_size;
tmp = 0.0f;
for (int j = start; j < end; j += block_size) {
const float xi = x[j] - mean;
dst[j] = xi;
tmp += xi * xi;
}
tmp = warp_reduce_sum(tmp);
if (block_size > WARP_SIZE) {
__shared__ float s_sum[32];
const int warp_id = threadIdx.x / WARP_SIZE;
const int lane_id = threadIdx.x % WARP_SIZE;
if (lane_id == 0) {
s_sum[warp_id] = tmp;
}
__syncthreads();
tmp = s_sum[lane_id];
tmp = warp_reduce_sum(tmp);
}
const float variance = tmp / group_size;
const float scale = rsqrtf(variance + eps);
for (int j = start; j < end; j += block_size) {
dst[j] *= scale;
}
}
template <int block_size>
static __global__ void rms_norm_f32(const float * x, float * dst, const int ncols, const float eps) {
const int row = blockIdx.x*blockDim.y + threadIdx.y;
const int tid = threadIdx.x;
x += int64_t(row)*ncols;
dst += int64_t(row)*ncols;
float tmp = 0.0f; // partial sum for thread in warp
for (int col = tid; col < ncols; col += block_size) {
const float xi = x[col];
tmp += xi * xi;
}
// sum up partial sums
tmp = warp_reduce_sum(tmp);
if constexpr (block_size > WARP_SIZE) {
static_assert(block_size == 1024, "unexpected block_size");
__shared__ float s_sum[32];
const int warp_id = threadIdx.x / WARP_SIZE;
const int lane_id = threadIdx.x % WARP_SIZE;
if (lane_id == 0) {
s_sum[warp_id] = tmp;
}
__syncthreads();
tmp = s_sum[lane_id];
tmp = warp_reduce_sum(tmp);
}
const float mean = tmp / ncols;
const float scale = rsqrtf(mean + eps);
for (int col = tid; col < ncols; col += block_size) {
dst[col] = scale * x[col];
}
}
template <int block_size>
static __global__ void rms_norm_back_f32(
const float * grad, const float * xf, float * dst, const int ncols, const float eps) {
const int row = blockIdx.x*blockDim.y + threadIdx.y;
const int tid = threadIdx.x;
grad += int64_t(row)*ncols;
xf += int64_t(row)*ncols;
dst += int64_t(row)*ncols;
float sum_xx = 0.0f; // sum for squares of x, equivalent to forward pass
float sum_xg = 0.0f; // sum for x * gradient, needed because RMS norm mixes inputs
for (int col = tid; col < ncols; col += block_size) {
const float xfi = xf[col];
sum_xx += xfi * xfi;
sum_xg += xfi * grad[col];
}
// sum up partial sums
sum_xx = warp_reduce_sum(sum_xx);
sum_xg = warp_reduce_sum(sum_xg);
if constexpr (block_size > WARP_SIZE) {
static_assert(block_size == 1024, "unexpected block_size");
__shared__ float s_sum_xx[32];
__shared__ float s_sum_xg[32];
const int warp_id = threadIdx.x / WARP_SIZE;
const int lane_id = threadIdx.x % WARP_SIZE;
if (lane_id == 0) {
s_sum_xx[warp_id] = sum_xx;
s_sum_xg[warp_id] = sum_xg;
}
__syncthreads();
sum_xx = s_sum_xx[lane_id];
sum_xx = warp_reduce_sum(sum_xx);
sum_xg = s_sum_xg[lane_id];
sum_xg = warp_reduce_sum(sum_xg);
}
const float mean_eps = sum_xx / ncols + eps;
const float sum_eps = sum_xx + ncols*eps;
const float scale_grad = rsqrtf(mean_eps);
const float scale_x = -scale_grad * sum_xg/sum_eps;
for (int col = tid; col < ncols; col += block_size) {
dst[col] = scale_grad*grad[col] + scale_x*xf[col];
}
}
static void norm_f32_cuda(const float * x, float * dst, const int ncols, const int nrows, const float eps, cudaStream_t stream) {
if (ncols < 1024) {
const dim3 block_dims(WARP_SIZE, 1, 1);
norm_f32<WARP_SIZE><<<nrows, block_dims, 0, stream>>>(x, dst, ncols, eps);
} else {
const dim3 block_dims(1024, 1, 1);
norm_f32<1024><<<nrows, block_dims, 0, stream>>>(x, dst, ncols, eps);
}
}
static void group_norm_f32_cuda(
const float * x, float * dst, const int num_groups, const float eps, const int group_size, const int ne_elements, cudaStream_t stream) {
if (group_size < 1024) {
const dim3 block_dims(WARP_SIZE, 1, 1);
group_norm_f32<WARP_SIZE><<<num_groups, block_dims, 0, stream>>>(x, dst, group_size, ne_elements, eps);
} else {
const dim3 block_dims(1024, 1, 1);
group_norm_f32<1024><<<num_groups, block_dims, 0, stream>>>(x, dst, group_size, ne_elements, eps);
}
}
static void rms_norm_f32_cuda(const float * x, float * dst, const int ncols, const int nrows, const float eps, cudaStream_t stream) {
if (ncols < 1024) {
const dim3 block_dims(WARP_SIZE, 1, 1);
rms_norm_f32<WARP_SIZE><<<nrows, block_dims, 0, stream>>>(x, dst, ncols, eps);
} else {
const dim3 block_dims(1024, 1, 1);
rms_norm_f32<1024><<<nrows, block_dims, 0, stream>>>(x, dst, ncols, eps);
}
}
static void rms_norm_back_f32_cuda(const float * grad, const float * xf, float * dst, const int ncols, const int nrows, const float eps, cudaStream_t stream) {
if (ncols < 1024) {
const dim3 block_dims(WARP_SIZE, 1, 1);
rms_norm_back_f32<WARP_SIZE><<<nrows, block_dims, 0, stream>>>(grad, xf, dst, ncols, eps);
} else {
const dim3 block_dims(1024, 1, 1);
rms_norm_back_f32<1024><<<nrows, block_dims, 0, stream>>>(grad, xf, dst, ncols, eps);
}
}
void ggml_cuda_op_norm(ggml_backend_cuda_context & ctx, ggml_tensor * dst) {
const ggml_tensor * src0 = dst->src[0];
const float * src0_d = (const float *)src0->data;
float * dst_d = (float *)dst->data;
cudaStream_t stream = ctx.stream();
GGML_ASSERT(ggml_is_contiguous(src0));
GGML_ASSERT(src0->type == GGML_TYPE_F32);
GGML_ASSERT( dst->type == GGML_TYPE_F32);
const int64_t ne00 = src0->ne[0];
const int64_t nrows = ggml_nrows(src0);
float eps;
memcpy(&eps, dst->op_params, sizeof(float));
GGML_ASSERT(eps >= 0.0f);
norm_f32_cuda(src0_d, dst_d, ne00, nrows, eps, stream);
}
void ggml_cuda_op_group_norm(ggml_backend_cuda_context & ctx, ggml_tensor * dst) {
const ggml_tensor * src0 = dst->src[0];
const float * src0_d = (const float *)src0->data;
float * dst_d = (float *)dst->data;
cudaStream_t stream = ctx.stream();
GGML_ASSERT(ggml_is_contiguous(src0));
GGML_ASSERT(src0->type == GGML_TYPE_F32);
GGML_ASSERT( dst->type == GGML_TYPE_F32);
int num_groups = dst->op_params[0];
float eps;
memcpy(&eps, dst->op_params + 1, sizeof(float));
GGML_ASSERT(eps >= 0.0f);
int group_size = src0->ne[0] * src0->ne[1] * ((src0->ne[2] + num_groups - 1) / num_groups);
group_norm_f32_cuda(src0_d, dst_d, num_groups * src0->ne[3], eps, group_size, ggml_nelements(src0), stream);
}
void ggml_cuda_op_rms_norm(ggml_backend_cuda_context & ctx, ggml_tensor * dst) {
const ggml_tensor * src0 = dst->src[0];
const float * src0_d = (const float *)src0->data;
float * dst_d = (float *)dst->data;
cudaStream_t stream = ctx.stream();
GGML_ASSERT(ggml_is_contiguous(src0));
GGML_ASSERT(src0->type == GGML_TYPE_F32);
GGML_ASSERT( dst->type == GGML_TYPE_F32);
const int64_t ne00 = src0->ne[0];
const int64_t nrows = ggml_nrows(src0);
float eps;
memcpy(&eps, dst->op_params, sizeof(float));
GGML_ASSERT(eps >= 0.0f);
rms_norm_f32_cuda(src0_d, dst_d, ne00, nrows, eps, stream);
}
void ggml_cuda_op_rms_norm_back(ggml_backend_cuda_context & ctx, ggml_tensor * dst) {
const ggml_tensor * grad = dst->src[0]; // gradients
const ggml_tensor * src0f = dst->src[1]; // src0 from forward pass
const float * grad_d = (const float *) grad->data;
const float * src0f_d = (const float *) src0f->data;
float * dst_d = (float *) dst->data;
cudaStream_t stream = ctx.stream();
GGML_ASSERT(ggml_is_contiguous(grad));
GGML_ASSERT( grad->type == GGML_TYPE_F32);
GGML_ASSERT(src0f->type == GGML_TYPE_F32);
GGML_ASSERT( dst->type == GGML_TYPE_F32);
const int64_t ne00 = src0f->ne[0];
const int64_t nrows = ggml_nrows(src0f);
float eps;
memcpy(&eps, dst->op_params, sizeof(float));
GGML_ASSERT(eps >= 0.0f);
rms_norm_back_f32_cuda(grad_d, src0f_d, dst_d, ne00, nrows, eps, stream);
}