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CUDA: enable FA for FP32 KV cache (#16546)

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This commit is contained in:
Johannes Gäßler
2025-10-14 14:22:47 +02:00
committed by GitHub
parent 1ee9d0b415
commit 9c7185dd28
2 changed files with 14 additions and 14 deletions
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9
ggml/src/ggml-cuda/fattn-vec.cuh
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@@ -516,8 +516,8 @@ void ggml_cuda_flash_attn_ext_vec_case_impl(ggml_backend_cuda_context & ctx, ggm
const int nthreads = ggml_cuda_fattn_vec_get_nthreads_host(cc);
const int nwarps = nthreads / WARP_SIZE;
fattn_kernel_t fattn_kernel = flash_attn_ext_vec<D, cols_per_block, type_K, type_V, use_logit_softcap>;
constexpr bool need_f16_K = false;
constexpr bool need_f16_V = false;
const bool need_f16_K = type_K == GGML_TYPE_F16;
const bool need_f16_V = type_V == GGML_TYPE_F16;
constexpr size_t nbytes_shared = 0;
launch_fattn<D, cols_per_block, 1>(ctx, dst, fattn_kernel, nwarps, nbytes_shared, D, need_f16_K, need_f16_V, false);
}
@@ -526,11 +526,6 @@ template <int D, ggml_type type_K, ggml_type type_V>
void ggml_cuda_flash_attn_ext_vec_case(ggml_backend_cuda_context & ctx, ggml_tensor * dst) {
const ggml_tensor * KQV = dst;
const ggml_tensor * Q = dst->src[0];
const ggml_tensor * K = dst->src[1];
const ggml_tensor * V = dst->src[2];
GGML_ASSERT(K->type == type_K);
GGML_ASSERT(V->type == type_V);
float logit_softcap;
memcpy(&logit_softcap, (const float *) KQV->op_params + 2, sizeof(float));

19
ggml/src/ggml-cuda/fattn.cu
View File

@@ -116,11 +116,15 @@ static void ggml_cuda_flash_attn_ext_mma_f16(ggml_backend_cuda_context & ctx, gg
}
}
#define FATTN_VEC_CASE(D, type_K, type_V) \
if (Q->ne[0] == (D) && K->type == (type_K) && V->type == (type_V)) { \
ggml_cuda_flash_attn_ext_vec_case<D, type_K, type_V>(ctx, dst); \
return; \
} \
#define FATTN_VEC_CASE(D, type_K, type_V) \
{ \
const bool type_K_okay = K->type == (type_K) || (K->type == GGML_TYPE_F32 && (type_K) == GGML_TYPE_F16); \
const bool type_V_okay = V->type == (type_V) || (V->type == GGML_TYPE_F32 && (type_V) == GGML_TYPE_F16); \
if (Q->ne[0] == (D) && type_K_okay && type_V_okay) { \
ggml_cuda_flash_attn_ext_vec_case<D, type_K, type_V>(ctx, dst); \
return; \
} \
} \
#define FATTN_VEC_CASES_ALL_D(type_K, type_V) \
FATTN_VEC_CASE( 64, type_K, type_V) \
@@ -247,6 +251,7 @@ static best_fattn_kernel ggml_cuda_get_best_fattn_kernel(const int device, const
#endif // GGML_CUDA_FA_ALL_QUANTS
switch (K->type) {
case GGML_TYPE_F32:
case GGML_TYPE_F16:
break;
case GGML_TYPE_Q4_1:
@@ -272,7 +277,7 @@ static best_fattn_kernel ggml_cuda_get_best_fattn_kernel(const int device, const
// If Turing tensor cores available, use them:
if (turing_mma_available(cc) && K->ne[1] % FATTN_KQ_STRIDE == 0 && Q->ne[0] != 40) {
if (can_use_vector_kernel) {
if (K->type == GGML_TYPE_F16 && V->type == GGML_TYPE_F16) {
if (!ggml_is_quantized(K->type) && !ggml_is_quantized(V->type)) {
if (cc >= GGML_CUDA_CC_ADA_LOVELACE && Q->ne[1] == 1 && Q->ne[3] == 1 && !(gqa_ratio > 4 && K->ne[1] >= 8192)) {
return BEST_FATTN_KERNEL_VEC;
}
@@ -305,7 +310,7 @@ static best_fattn_kernel ggml_cuda_get_best_fattn_kernel(const int device, const
// If there are no tensor cores available, use the generic tile kernel:
if (can_use_vector_kernel) {
if (K->type == GGML_TYPE_F16 && V->type == GGML_TYPE_F16) {
if (!ggml_is_quantized(K->type) && !ggml_is_quantized(V->type)) {
if (Q->ne[1] == 1) {
if (!gqa_opt_applies) {
return BEST_FATTN_KERNEL_VEC;