ubatch : new splitting logic

ggml-ci

Author: ggerganov

src/llama-batch.cpp

@@ -2,118 +2,146 @@
 
 #include "llama.h"
 
+#include "llama-cparams.h"
+
 #include <array>
 #include <vector>
 #include <set>
+#include <bitset>
+#include <unordered_map>
 
-// very similar to llama_batch,
-// but has more metadata about sequences
+// keep this struct lightweight
+// it points to data in `llama_batch_allocr`
 struct llama_ubatch {
     bool equal_seqs;
     // TODO: whole_seqs for embeddings?
 
     uint32_t n_tokens;     // total tokens (n_seq_tokens * n_seqs)
-    uint32_t n_seq_tokens; // tokens per sequence
-    uint32_t n_seqs;
-
-    llama_token  *  token;    // [n_tokens]
-    float        *  embd;     // [n_embd, n_tokens]
-    llama_pos    *  pos;      // [n_tokens]
-    int32_t      *  n_seq_id; // [n_seqs]
-    llama_seq_id ** seq_id;   // [n_seqs]
-    int8_t       *  output;   // [n_tokens]
-};
-
-struct llama_sbatch_seq {
-    int32_t n_seq_id;
-
-    llama_seq_id * seq_id;
-
-    size_t offset;
-    size_t length;
-};
-
-// sequence-length-aware batch splitting
-struct llama_sbatch {
-    // tokens left in this batch
-    size_t n_tokens;
-
-    size_t n_embd;
-
-    // sorted indices into the batch
-    std::vector<int64_t> ids;
-    // batch indices of the output
-    std::vector<int64_t> out_ids;
-    std::vector<llama_sbatch_seq> seq;
-
-    const llama_batch * batch = nullptr;
-
-    // buffers for the ubatches
-    // TODO: very hacky, this needs a complete rework
-    struct ubatch_data {
-        std::vector<llama_token>    token;
-        std::vector<float>          embd;
-        std::vector<llama_pos>      pos;
-        std::vector<int32_t>        n_seq_id;
-        std::vector<llama_seq_id *> seq_id;
-        std::vector<int8_t>         output;
-    };
-
-    std::vector<ubatch_data> udatas;
-
-    llama_ubatch reserve_ubatch(size_t n_ubatch, bool has_embd = false);
-
-    void add_seq_to_ubatch(llama_ubatch & ubatch, llama_sbatch_seq & seq, size_t length);
-
-    // simple split, unknown number of sequences of unequal lengths
-    llama_ubatch split_simple(size_t n_ubatch);
-
-    // make batches of equal-length sequences
-    llama_ubatch split_equal(size_t n_ubatch);
-
-    // sequence-wise split
-    llama_ubatch split_seq(size_t n_ubatch);
-
-    llama_sbatch() = default;
-    llama_sbatch(const llama_batch & batch, size_t n_embd, bool simple_split = false);
+    uint32_t n_seq_tokens; // tokens per sequence set
+    uint32_t n_seqs;       // sequence sets in the ubatch
+    uint32_t n_seqs_unq;   // unique sequence ids in the ubatch
+
+    // seq_id_unq: unique sequence ids in the ubatch
+    // seq_idx:    indices of the unique sequence ids in the ubatch in [0, n_seqs_unq)
+    //             used for extracting sequence pooled embeddings
+
+    //                          // size               | idx | val
+    llama_token  *  token;      // [n_tokens]         | i   | id, token
+    float        *  embd;       // [n_embd, n_tokens] | i   | embd
+    llama_pos    *  pos;        // [n_tokens]         | i   | pos
+    int32_t      *  n_seq_id;   // [n_tokens]         | i   | -
+    llama_seq_id ** seq_id;     // [n_tokens]         | s   | s0, s1, seq_id
+    llama_seq_id *  seq_id_unq; // [n_seqs_unq]       | s   | seq_id
+    int32_t      *  seq_idx;    // [LLAMA_MAX_SEQ]    | -   | seq_idx
+    int8_t       *  output;     // [n_tokens]         | i   | -
 };
 
-// a helper for sanitizing and fulfilling a batch
+// a helper for sanitizing, fulfilling and splitting a batch
 class llama_batch_allocr {
 public:
-    llama_batch_allocr();
+    llama_batch_allocr(uint32_t n_pos_per_embd);
 
     // sanitize and auto-gen missing data in the input batch
     // memory is optional. if provided will be used to check for sequence continuity and to determine the positions
     bool init(
             const llama_batch & batch_inp,
             const llama_vocab & vocab,
             const llama_memory_i * memory,
-            bool embd_all);
+            uint32_t n_embd,
+            bool output_all);
 
     const llama_batch & get_batch() const;
 
+    uint32_t get_n_tokens()  const;
     uint32_t get_n_outputs() const;
 
+    // the array of output indices in the order they were encountered during the ubatch splitting
+    std::vector<int32_t> & get_out_ids();
+
+    // min/max positions of each sequence in the current ubatch
     llama_pos seq_pos_min(llama_seq_id seq_id) const;
     llama_pos seq_pos_max(llama_seq_id seq_id) const;
 
+    // call once before splitting the batch to reset the internal state
+    void split_reset();
+
+    // simple split, unknown number of sequence sets of unequal lengths
+    llama_ubatch split_simple(uint32_t n_ubatch);
+
+    // make ubatches of equal-length sequences sets
+    llama_ubatch split_equal(uint32_t n_ubatch);
+
+    // sequence-set-wise split - each ubatch contains a single sequence-set
+    llama_ubatch split_seq(uint32_t n_ubatch);
+
+    // a helper method for creating a well-defined ubatch of tokens
+    // TODO: support embeddings if needed in the future
+    llama_ubatch ubatch_reserve(uint32_t n_seq_tokens, uint32_t n_seqs);
+
 private:
     void clear();
 
+    // create the next ubatch based on the provided batch indices (idxs) and the number of sequence sets (n_seqs)
+    // return llama_ubatch.n_tokens == 0 if the entire batch was consumed
+    llama_ubatch ubatch_add(const std::vector<int32_t> & idxs, uint32_t n_seqs, bool equal_seqs);
+
+    // for debugging, start with LLAMA_BATCH_DEBUG=2
+    void ubatch_print(const llama_ubatch & ubatch, int debug);
+
     llama_batch batch;
 
+    // only for debugging purposes
+    const llama_vocab * vocab;
+
+    // TODO: this is more of a temporary solution until we have a better way to handle multiple positions per token/embd
+    //       ref: https://github.com/ggml-org/llama.cpp/issues/13694#issuecomment-2983871762
+    const uint32_t n_pos_per_embd;
+
+    uint32_t n_embd;
     uint32_t n_outputs;
 
     std::array<llama_seq_id, 1> seq_id_0 = { 0 }; // default sequence id
 
     std::vector<llama_pos>      pos;
     std::vector<int32_t>        n_seq_id;
     std::vector<llama_seq_id *> seq_id;
+    std::vector<llama_seq_id>   seq_id_unq;
+    std::vector<int32_t>        seq_idx;
     std::vector<int8_t>         output;
 
-    std::vector<std::set<llama_pos>> seq_pos; // seq_pos[s]: the set of positions in sequence s
-    std::vector<std::vector<bool>>   seq_cpl; // seq_cpl[s0][s1]: if sequence s0 is coupled to sequence s1
+    using pos_set_t = std::set<llama_pos>;
+    using seq_cpl_t = std::vector<bool>;
+
+    std::vector<pos_set_t> seq_pos; // seq_pos[s]: the set of positions in sequence s
+    std::vector<seq_cpl_t> seq_cpl; // seq_cpl[s0][s1]: if sequence s0 is coupled to sequence s1
+
+    using idx_vec_t = std::vector<int32_t>;
+    using seq_set_t = std::bitset<LLAMA_MAX_SEQ>;
+
+    std::vector<seq_set_t> seq_set; // seq_set[i]: the sequence set of token i
+
+    std::unordered_map<seq_set_t, idx_vec_t> seq_set_map; // the indices at which the sequence set appears
+
+    // batch indices of the output
+    std::vector<int32_t> out_ids;
+
+    // used[i] indicates if token i has already been used in a previous ubatch
+    std::vector<bool> used;
+
+    // llama_ubatch points to this data:
+    struct ubatch {
+        std::vector<llama_token>    token;
+        std::vector<float>          embd;
+        std::vector<llama_pos>      pos;
+        std::vector<int32_t>        n_seq_id;
+        std::vector<llama_seq_id *> seq_id;
+        std::vector<llama_seq_id>   seq_id_unq;
+        std::vector<int32_t>        seq_idx;
+        std::vector<int8_t>         output;
+    };
+
+    // current splitting state:
+    std::vector<ubatch> ubatches;
 
     int debug;
 };