import torch import math query = torch.load("query_states_sdpa_3.pt") key = torch.load("key_states_sdpa_3.pt") value = torch.load("value_states_sdpa_3.pt") print("query", query.device, query.dtype, query.is_contiguous(), query.shape) print("key", key.device, key.dtype, key.is_contiguous(), key.shape) print("value", value.device, value.dtype, value.is_contiguous(), value.shape) torch.set_printoptions(threshold=1000000, precision=6) def scaled_dot_product_attention(query, key, value, is_causal: bool, custom_cast: bool): scale_factor = math.sqrt(1 / math.sqrt(query.size(-1))) assert not is_causal softmax_inp = ((query * scale_factor) @ ((key * scale_factor).transpose(-2, -1))) if custom_cast: attn_weight = torch.softmax( softmax_inp, dim=-1, dtype=torch.float32 ).to(query.dtype) else: attn_weight = torch.softmax(softmax_inp, dim=-1) return attn_weight @ value, softmax_inp is_causal = False with torch.no_grad(): with torch.backends.cuda.sdp_kernel(enable_flash=False, enable_math=True, enable_mem_efficient=False): res_sdpa = torch.nn.functional.scaled_dot_product_attention(query, key, value, is_causal=is_causal, attn_mask=None) res_eager_cast, softmax_inp = scaled_dot_product_attention(query, key, value, is_causal=is_causal, custom_cast=True) res_eager_no_cast, _ = scaled_dot_product_attention(query, key, value, is_causal=is_causal, custom_cast=False) res_softmax_0 = torch.softmax(softmax_inp, dim=-1) res_softmax_1 = torch.softmax(softmax_inp, dim=-1, dtype=torch.float32).to(torch.float16) print("-----") absdiff = (res_softmax_0 - res_softmax_1).abs() print("max absdiff softmax", absdiff.max()) print("median absdiff softmax", absdiff.median()) print("-----") # These cast do not seem to matter. res_sdpa = res_sdpa.to(torch.float32) res_eager_cast = res_eager_cast.to(torch.float32) res_eager_no_cast = res_eager_no_cast.to(torch.float32) absdiff_nocast = (res_sdpa - res_eager_no_cast).abs() absdiff_cast = (res_sdpa - res_eager_cast).abs() print("SDPA max absdiff (no cast):", absdiff_nocast.max()) print("SDPA max absdiff (with cast):", absdiff_cast.max()) print("argwhere absdiff no cast > 0.0001", torch.argwhere(absdiff_nocast > 1e-4)) print("argwhere absdiff with cast > 0.0001", torch.argwhere(absdiff_cast > 1e-4))