spec : parallel drafting support (#22838)
* spec : refactor * spec : drop support for incompatible vocabs * spec : update common_speculative_init() * cont : pass seq_id * cont : dedup ctx_seq_rm_type * server : sketch the ctx_dft decode loop * server : draft prompt cache and checkpoints * server : improve ctx names * server, spec : transition to unified spec context * cont : sync main and drft contexts * cont : async drft eval when possible * cont : handle non-ckpt models * cont : pass correct n_past for drafting * cont : process images throught the draft context * spec : handle draft running out of context * server : fix mtmd draft processing * server : fix URL for draft model * server : add comment * server : clean-up + dry * speculative-simple : update * spec : fix n_past type * server : fix slot ctx_drft ptr * tools : update readme * naming : improve consistency * spec : refactor for multi-sequence speculative context * cont : prepare params * cont : prepare params * spec : support parallel drafts * server : support parallel drafting * llama : reuse device buffers when possible * server, spec : clean-up * cont : clean-up * cont : minor * spec : reset `drafting` flag at the end * spec : introduce `common_speculative_process()` * spec : allow for multiple spec types (chain of speculators) * replace old type field of type common_speculative_type in the common_params_speculative struct with a vector to allow multiple types to be specified * introduce common_get_enabled_speculative_impls(const std::vector<enum common_speculative_type>) to figure out which implementations the user has enabled * introduce common_speculative_type_from_names(const std::vector<std::string> & names) to parse the already user provided spec types * all speculators run sequentially, best one wins (we verify its drafted tokens) * maximize expected accepted tokens for current round by calculating the product between the probability of accepting current token (n_acc_tokens / n_gen_drafts) and the draft's length --------- Co-authored-by: Petros Sideris <petros.sideris@nokia.com>
This commit is contained in:
+5
-36
@@ -622,10 +622,6 @@ static bool common_params_parse_ex(int argc, char ** argv, common_params_context
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for (auto & seq_breaker : params.sampling.dry_sequence_breakers) {
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string_process_escapes(seq_breaker);
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}
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for (auto & pair : params.speculative.draft.replacements) {
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string_process_escapes(pair.first);
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string_process_escapes(pair.second);
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}
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}
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if (!params.kv_overrides.empty()) {
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@@ -3518,13 +3514,6 @@ common_params_context common_params_parser_init(common_params & params, llama_ex
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params.speculative.draft.p_min = std::stof(value);
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}
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).set_spec().set_examples({LLAMA_EXAMPLE_SPECULATIVE, LLAMA_EXAMPLE_SERVER, LLAMA_EXAMPLE_CLI}).set_env("LLAMA_ARG_SPEC_DRAFT_P_MIN"));
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add_opt(common_arg(
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{"--spec-draft-ctx-size", "-cd", "--ctx-size-draft"}, "N",
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string_format("size of the prompt context for the draft model (default: %d, 0 = loaded from model)", params.speculative.draft.n_ctx),
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[](common_params & params, int value) {
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params.speculative.draft.n_ctx = value;
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}
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).set_spec().set_examples({LLAMA_EXAMPLE_SPECULATIVE, LLAMA_EXAMPLE_SERVER, LLAMA_EXAMPLE_CLI}).set_env("LLAMA_ARG_SPEC_DRAFT_CTX_SIZE"));
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add_opt(common_arg(
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{"--spec-draft-device", "-devd", "--device-draft"}, "<dev1,dev2,..>",
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"comma-separated list of devices to use for offloading the draft model (none = don't offload)\n"
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@@ -3561,32 +3550,12 @@ common_params_context common_params_parser_init(common_params & params, llama_ex
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}
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).set_spec().set_examples({LLAMA_EXAMPLE_SPECULATIVE, LLAMA_EXAMPLE_SERVER, LLAMA_EXAMPLE_CLI}).set_env("LLAMA_ARG_SPEC_DRAFT_MODEL"));
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add_opt(common_arg(
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{"--spec-draft-replace", "--spec-replace"}, "TARGET", "DRAFT",
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"translate the string in TARGET into DRAFT if the draft model and main model are not compatible",
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[](common_params & params, const std::string & tgt, const std::string & dft) {
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params.speculative.draft.replacements.push_back({ tgt, dft });
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}
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).set_spec().set_examples({LLAMA_EXAMPLE_SPECULATIVE, LLAMA_EXAMPLE_SERVER, LLAMA_EXAMPLE_CLI}));
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add_opt(common_arg(
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{"--spec-type"}, "[none|ngram-cache|ngram-simple|ngram-map-k|ngram-map-k4v|ngram-mod]",
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{"--spec-type"}, common_speculative_all_types_str(),
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string_format("type of speculative decoding to use when no draft model is provided (default: %s)\n",
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common_speculative_type_to_str(params.speculative.type).c_str()),
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common_speculative_type_name_str(params.speculative.types).c_str()),
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[](common_params & params, const std::string & value) {
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if (value == "none") {
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params.speculative.type = COMMON_SPECULATIVE_TYPE_NONE;
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} else if (value == "ngram-cache") {
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params.speculative.type = COMMON_SPECULATIVE_TYPE_NGRAM_CACHE;
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} else if (value == "ngram-simple") {
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params.speculative.type = COMMON_SPECULATIVE_TYPE_NGRAM_SIMPLE;
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} else if (value == "ngram-map-k") {
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params.speculative.type = COMMON_SPECULATIVE_TYPE_NGRAM_MAP_K;
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} else if (value == "ngram-map-k4v") {
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params.speculative.type = COMMON_SPECULATIVE_TYPE_NGRAM_MAP_K4V;
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} else if (value == "ngram-mod") {
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params.speculative.type = COMMON_SPECULATIVE_TYPE_NGRAM_MOD;
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} else {
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throw std::invalid_argument("unknown speculative decoding type without draft model");
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}
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const auto enabled_types = string_split<std::string>(value, ',');
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params.speculative.types = common_speculative_types_from_names(enabled_types);
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}
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).set_spec().set_examples({LLAMA_EXAMPLE_SPECULATIVE, LLAMA_EXAMPLE_SERVER, LLAMA_EXAMPLE_CLI}).set_env("LLAMA_ARG_SPEC_TYPE"));
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add_opt(common_arg(
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@@ -4075,7 +4044,7 @@ common_params_context common_params_parser_init(common_params & params, llama_ex
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{"--spec-default"},
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string_format("enable default speculative decoding config"),
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[](common_params & params) {
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params.speculative.type = COMMON_SPECULATIVE_TYPE_NGRAM_MOD;
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params.speculative.types = { COMMON_SPECULATIVE_TYPE_NGRAM_MOD };
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params.speculative.ngram_mod.n_match = 24;
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params.speculative.ngram_mod.n_min = 48;
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params.speculative.ngram_mod.n_max = 64;
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