vbatts/llama.cpp
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Use Longest Common Prefix (LCP) instead of LCS

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sasha0552 2024-06-07 14:09:11 +00:00 • committed by GitHub
parent f1164112de
commit 36083dca2c
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4 changed files with 25 additions and 67 deletions
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8
common/common.cpp
View file

@ -1460,12 +1460,12 @@ bool gpt_params_find_arg(int argc, char ** argv, const std::string & arg, gpt_pa
params.chat_template = argv[i];
return true;
}
if (arg == "--lcs-similarity") {
if (arg == "--lcp-similarity") {
if (++i >= argc) {
invalid_param = true;
return true;
}
params.lcs_similarity = std::stof(argv[i]);
params.lcp_similarity = std::stof(argv[i]);
return true;
}
if (arg == "-pps") {
@ -1839,8 +1839,8 @@ void gpt_params_print_usage(int /*argc*/, char ** argv, const gpt_params & param
"set custom jinja chat template (default: template taken from model's metadata)\n"
"only commonly used templates are accepted:\n"
"https://github.com/ggerganov/llama.cpp/wiki/Templates-supported-by-llama_chat_apply_template" });
options.push_back({ "server", " --lcs-similarity SIMILARITY",
"how much the prompt of a request must match the prompt of a slot in order to use that slot (default: %.2f)\n", params.lcs_similarity });
options.push_back({ "server", " --lcp-similarity SIMILARITY",
"how much the prompt of a request must match the prompt of a slot in order to use that slot (default: %.2f)\n", params.lcp_similarity });
#ifndef LOG_DISABLE_LOGS
options.push_back({ "logging" });

2
common/common.h
View file

@ -202,7 +202,7 @@ struct gpt_params {
std::string slot_save_path;
float lcs_similarity = 0.0f;
float lcp_similarity = 0.0f;
// batched-bench params
bool is_pp_shared = false;

26
examples/server/server.cpp
View file

@ -647,8 +647,8 @@ struct server_context {
server_metrics metrics;
// Longest Common Substring similarity for slot selection
float lcs_similarity = 0.0f;
// Longest Common Prefix similarity for slot selection
float lcp_similarity = 0.0f;
~server_context() {
if (ctx) {
@ -812,8 +812,8 @@ struct server_context {
server_slot * ret = nullptr;
// find the slot that has at least n% prompt similarity
if (ret == nullptr && lcs_similarity != 0.0f && !prompt.empty()) {
int max_lcs_len = 0;
if (ret == nullptr && lcp_similarity != 0.0f && !prompt.empty()) {
int max_lcp_len = 0;
float similarity = 0;
for (server_slot & slot : slots) {
@ -833,23 +833,23 @@ struct server_context {
// length of the current slot's prompt
int slot_prompt_len = slot_prompt.size();
// length of the longest common substring between the current slot's prompt and the input prompt
int lcs_len = lcs_length(slot_prompt, prompt);
// length of the Longest Common Prefix between the current slot's prompt and the input prompt
int lcp_len = common_part(slot_prompt, prompt);
// fraction of the common substring length compared to the current slot's prompt length
similarity = static_cast<float>(lcs_len) / slot_prompt_len;
similarity = static_cast<float>(lcp_len) / slot_prompt_len;
// select the current slot if the criteria match
if (lcs_len > max_lcs_len && similarity > lcs_similarity) {
max_lcs_len = lcs_len;
if (lcp_len > max_lcp_len && similarity > lcp_similarity) {
max_lcp_len = lcp_len;
ret = &slot;
}
}
if (ret != nullptr) {
LOG_VERBOSE("selected slot by lcs similarity", {
LOG_VERBOSE("selected slot by lcp similarity", {
{"id_slot", ret->id},
{"max_lcs_len", max_lcs_len},
{"max_lcp_len", max_lcp_len},
{"similarity", similarity},
});
}
@ -2568,8 +2568,8 @@ int main(int argc, char ** argv) {
log_data["api_key"] = "api_key: " + std::to_string(params.api_keys.size()) + " keys loaded";
}
// Longest Common Substring similarity for slot selection
ctx_server.lcs_similarity = params.lcs_similarity;
// Longest Common Prefix similarity for slot selection
ctx_server.lcp_similarity = params.lcp_similarity;
// load the model
if (!ctx_server.load_model(params)) {

56
examples/server/utils.hpp
View file

@ -253,6 +253,13 @@ static size_t common_part(const std::vector<llama_token> & a, const std::vector<
return i;
}
static size_t common_part(const std::string & a, const std::string & b) {
size_t i;
for (i = 0; i < a.size() && i < b.size() && a[i] == b[i]; i++) {}
return i;
}
static bool ends_with(const std::string & str, const std::string & suffix) {
return str.size() >= suffix.size() && 0 == str.compare(str.size() - suffix.size(), suffix.size(), suffix);
}
@ -646,52 +653,3 @@ static json format_error_response(const std::string & message, const enum error_
{"type", type_str},
};
}
static int lcs_length(const std::string & str1, const std::string & str2) {
// check for empty strings
if (str1.empty() || str2.empty()) {
return 0;
}
// get the lengths of the input strings
int str1_len = str1.size();
int str2_len = str2.size();
// initialize the maximum length of the longest common subsequence (LCS)
int max_length = 0;
// use two rows instead of a 2D matrix to optimize space
std::vector<int> prev_row(str2_len + 1, 0);
std::vector<int> curr_row(str2_len + 1, 0);
// iterate through the characters of str1
for (int i = 1; i <= str1_len; i++) {
// iterate through the characters of str2
for (int j = 1; j <= str2_len; j++) {
// if characters at the current positions match
if (str1[i - 1] == str2[j - 1]) {
// if it's the first character of either string, set LCS length to 1
if (i == 1 || j == 1) {
curr_row[j] = 1;
} else {
// increment LCS length by 1 compared to the previous character
curr_row[j] = prev_row[j - 1] + 1;
}
// update max_length if necessary
if (curr_row[j] > max_length) {
max_length = curr_row[j];
}
} else {
// reset LCS length if characters don't match
curr_row[j] = 0;
}
}
// update the previous row for the next iteration
prev_row = curr_row;
}
// return the maximum length of the LCS
return max_length;
}