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Sparse attention : Generalize arch checks for A100 and above #73

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Jul 28, 2025
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Sparse attention : Generalize arch checks for A100 and above #73

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20 changes: 7 additions & 13 deletions csrc/flash_attn/flash_api_sparse.cpp
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Original file line number Diff line number Diff line change
Expand Up @@ -157,17 +157,14 @@ mha_fwd_sparse(at::Tensor &q, // batch_size x seqlen_q x num_heads x hea
std::optional<at::Generator> gen_) {

auto [cc_major, cc_minor] = get_compute_capability(get_current_device());
bool is_sm8x = cc_major == 8 && cc_minor >= 0;
bool is_sm90 = cc_major == 9 && cc_minor == 0;
TORCH_CHECK(is_sm90 || is_sm8x, "FlashAttention only supports Ampere GPUs or newer.");
// We will support Turing in the near future
// TORCH_CHECK(is_sm90 || is_sm8x || is_sm75, "FlashAttention only supports Turing GPUs or newer.");
bool is_sm8x_min = cc_major >= 8;
TORCH_CHECK(is_sm8x_min, "FlashAttention only supports Ampere GPUs or newer.");

auto q_dtype = q.dtype();
TORCH_CHECK(q_dtype == torch::kFloat16 || q_dtype == torch::kBFloat16,
"FlashAttention only support fp16 and bf16 data type");
if (q_dtype == torch::kBFloat16) {
TORCH_CHECK(is_sm90 || is_sm8x, "bfloat16 is only supported on Ampere GPUs or newer");
TORCH_CHECK(is_sm8x_min, "bfloat16 is only supported on Ampere GPUs or newer");
}
TORCH_CHECK(k.dtype() == q_dtype, "query and key must have the same dtype");
TORCH_CHECK(v.dtype() == q_dtype, "query and value must have the same dtype");
Expand Down Expand Up @@ -342,17 +339,14 @@ mha_varlen_fwd_sparse(at::Tensor &q, // total_q x num_heads x head_size, total_
std::optional<at::Generator> gen_) {

auto [cc_major, cc_minor] = get_compute_capability(get_current_device());
bool is_sm8x = cc_major == 8 && cc_minor >= 0;
bool is_sm90 = cc_major == 9 && cc_minor == 0;
TORCH_CHECK(is_sm90 || is_sm8x, "FlashAttention only supports Ampere GPUs or newer.");
// We will support Turing in the near future
// TORCH_CHECK(is_sm90 || is_sm8x || is_sm75, "FlashAttention only supports Turing GPUs or newer.");
bool is_sm8x_min = cc_major >= 8;
TORCH_CHECK(is_sm8x_min, "FlashAttention only supports Ampere GPUs or newer.");

auto q_dtype = q.dtype();
TORCH_CHECK(q_dtype == torch::kFloat16 || q_dtype == torch::kBFloat16,
"FlashAttention only support fp16 and bf16 data type");
if (q_dtype == torch::kBFloat16) {
TORCH_CHECK(is_sm90 || is_sm8x, "bfloat16 is only supported on Ampere GPUs or newer");
TORCH_CHECK(is_sm8x_min, "bfloat16 is only supported on Ampere GPUs or newer");
}
TORCH_CHECK(k.dtype() == q_dtype, "query and key must have the same dtype");
TORCH_CHECK(v.dtype() == q_dtype, "query and value must have the same dtype");
Expand Down Expand Up @@ -528,4 +522,4 @@ mha_varlen_fwd_sparse(at::Tensor &q, // total_q x num_heads x head_size, total_
return {out, softmax_lse};
}

} // namespace FLASH_NAMESPACE
} // namespace FLASH_NAMESPACE