csrc/kernels/params.h

#pragma once

////////////////////////////////////////////////////////////////////////////////////////////////////

struct Flash_fwd_mla_params {
    using index_t = int64_t;

    int b;              // batch size
    int s_q;
    int q_seq_per_hk;   // The number of q(s) per KV head, = h_q / h_k * s_q
    int d, d_v;         // K/V dimension
    int h_q, h_k;       // The number of Q/K heads
    int num_blocks;     // Number of blocks in total
    int q_head_per_hk;  // The number of q_head(s) per KV head, = h_q / h_k
    bool is_causal;
    float scale_softmax, scale_softmax_log2;
    
    void *__restrict__ q_ptr;
    void *__restrict__ k_ptr;
    void *__restrict__ o_ptr;
    void *__restrict__ softmax_lse_ptr;

    index_t q_batch_stride;
    index_t k_batch_stride;
    index_t o_batch_stride;
    index_t q_row_stride;
    index_t k_row_stride;
    index_t o_row_stride;
    index_t q_head_stride;
    index_t k_head_stride;
    index_t o_head_stride;

    int *__restrict__ block_table;
    index_t block_table_batch_stride;
    int page_block_size;
    int *__restrict__ seqlens_k_ptr;

    int *__restrict__ tile_scheduler_metadata_ptr;
    int num_sm_parts;
    int *__restrict__ num_splits_ptr;

    int total_num_splits;
    void *__restrict__ softmax_lseaccum_ptr;
    void *__restrict__ oaccum_ptr;
};

static constexpr int TileSchedulerMetaDataSize = 8;
// [begin_idx, begin_seqlen, end_idx, end_seqlen, begin_n_split_idx, _, _, _]

struct Mla_metadata_params {
    int *__restrict__ seqlens_k_ptr;
    int *__restrict__ tile_scheduler_metadata_ptr;
    int *__restrict__ num_splits_ptr;
    int batch_size;
    int block_size_n;
    int fixed_overhead_num_blocks;
    int num_sm_parts;
};