Skip to content

GitLab

Switch branch/tag
Find file Normal viewHistoryPermalink
fwd.cu 3.85 KB
Newer Older
shenzhe's avatar
Add DSA MLS sparse prefill dispatch  
shenzhe committed
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130 
#include "fwd.h"

#include <cstring>
#include <stdexcept>
#include <string>

#include "dispatch.h"

namespace gfx93::fwd::dsa_mls {

bool can_run(const SparseAttnFwdParams& params) {
    if (params.d_v != 512) return false;
    if (params.d_qk != 512 && params.d_qk != 576) return false;
    if (params.h_kv != 1) return false;
    if (params.h_q != 64 && params.h_q != 128) return false;
    if (!(params.topk <= 1024 || params.topk == 2048)) return false;
    if (params.topk == 2048 && (params.attn_sink != nullptr || params.topk_length != nullptr)) return false;
    return true;
}

bool should_run(const SparseAttnFwdParams& params) {
    if (!can_run(params)) return false;

    if (params.d_qk == 512 &&
        ((params.h_q == 64 && params.topk == 512) ||
         (params.h_q == 128 && params.topk == 1024))) {
        return true;
    }

    if (params.d_qk == 576 && params.h_q == 64 && params.topk == 2048 && params.s_kv >= 32768) {
        return true;
    }

    return false;
}

static Flash_fwd_mla_params_dsa make_legacy_params(const SparseAttnFwdParams& src) {
    if (!can_run(src)) {
        throw std::runtime_error(
            "DSA MLS sparse prefill only supports d_qk=512/576, d_v=512, "
            "h_kv=1, h_q=64/128, topk<=1024 or topk=2048 without attn_sink/topk_length");
    }

    Flash_fwd_mla_params_dsa dst;
    std::memset(&dst, 0, sizeof(dst));

    dst.layout = 1;
    dst.b = 1;
    dst.h = 1;
    dst.h_k = src.h_kv;
    dst.h_h_k_ratio = dst.h / dst.h_k;
    dst.mtp = 1;
    dst.ngroups = src.h_q / src.h_kv;
    dst.topk = src.topk;
    dst.d = src.d_qk;
    dst.d_v = src.d_v;
    dst.scale_softmax = src.sm_scale;
    dst.scale_softmax_log2 = src.sm_scale_div_log2;

    dst.cu_seqlens_q = nullptr;
    dst.cu_seqlens_k = nullptr;
    dst.cu_seqlens_k_new = nullptr;
    dst.topk_length = src.topk_length;
    dst.attn_sink = src.attn_sink;

    dst.q_ptr = src.q;
    dst.k_ptr = src.kv;
    dst.v_ptr = src.kv;
    dst.o_ptr = src.out;
    dst.sparse_indices = src.indices;
    dst.softmax_lse_ptr = src.lse;
    dst.scores_max_ptr = src.max_logits;
    dst.scores_sum_ptr = nullptr;

    dst.block_table = nullptr;
    dst.block_table_batch_stride = 0;
    dst.page_block_size = 0;
    dst.is_causal = false;

    dst.q_batch_stride = 0;
    dst.q_token_stride = src.stride_q_s_q;
    dst.q_head_stride = src.stride_q_h_q;
    dst.q_row_stride = dst.q_head_stride;

    dst.k_batch_stride = 0;
    dst.k_row_stride = src.stride_kv_s_kv;
    dst.k_head_stride = src.stride_kv_h_kv;
    dst.v_batch_stride = 0;
    dst.v_row_stride = src.stride_kv_s_kv;
    dst.v_head_stride = src.stride_kv_h_kv;

    dst.o_batch_stride = 0;
    dst.o_row_stride = src.h_q * src.d_v;
    dst.o_head_stride = src.d_v;

    dst.sparse_indices_batch_stride = 0;
    dst.sparse_indices_row_stride = src.stride_indices_s_q;
    dst.sparse_indices_head_stride = src.stride_indices_h_kv;
    dst.sparse_indices_topk_stride = 1;

    dst.seqlen_q = src.s_q * dst.ngroups;
    dst.seqlen_k = src.s_kv;
    dst.max_seqlen = src.s_q;
    dst.is_bf16 = true;
    dst.is_e4m3 = false;
    dst.is_int8 = false;
    dst.cu_count = src.num_sm;
    dst.seqlenq_ngroups_swapped = true;
    dst.is_seqlens_k_cumulative = false;
    dst.splitkv_use_fp32_as_accum = false;
    dst.num_splits = 0;
    dst.partition_size = src.topk;

    return dst;
}

void run(const SparseAttnFwdParams& params) {
    Flash_fwd_mla_params_dsa legacy_params = make_legacy_params(params);
    hipStream_t stream = reinterpret_cast<hipStream_t>(params.stream);

    if (params.d_qk == 512) {
        run_dsa_prefill_nopage_64_dispatch<BFloat16, 512, 512>(legacy_params, stream);
    } else if (params.d_qk == 576) {
        run_dsa_prefill_nopage_64_dispatch<BFloat16, 576, 512>(legacy_params, stream);
    } else {
        throw std::runtime_error("Unsupported d_qk value in DSA MLS sparse prefill");
    }
}

}  // namespace gfx93::fwd::dsa_mls