echodict/llama.cpp

1// Test for state restore with fragmented KV cache2// This tests the fix for: https://github.com/ggml-org/llama.cpp/issues/175273// The issue was that state restore required contiguous KV cache slots,4// which fails when the cache is fragmented.5//6// The fix changes find_slot(ubatch, true) to find_slot(ubatch, false)7// in state_read_meta(), allowing non-contiguous slot allocation.8 9#include "arg.h"10#include "common.h"11#include "llama.h"12 13#include <vector>14#include <cstdio>15#include <cstring>16 17int main(int argc, char ** argv) {18    common_params params;19 20    params.sampling.seed = 1234;21    params.kv_unified = true;22    params.n_parallel = 3;23    params.n_ctx = 256;24 25    common_init();26 27    if (!common_params_parse(argc, argv, params, LLAMA_EXAMPLE_COMMON)) {28        return 1;29    }30 31    // init32    common_init_result_ptr llama_init = common_init_from_params(params);33 34    llama_model * model = llama_init->model();35    llama_context * ctx = llama_init->context();36 37    if (model == nullptr || ctx == nullptr) {38        fprintf(stderr, "%s : failed to init\n", __func__);39        return 1;40    }41 42    GGML_UNUSED(model);43 44    // tokenize prompt45    std::vector<llama_token> tokens(70, 1);46 47    // interleave the 3 sequences:48    // 01201230123...49    llama_batch batch = llama_batch_init(params.n_parallel*tokens.size(), 0, 1);50    for (size_t i = 0; i < tokens.size(); i++) {51        for (int s = 0; s < params.n_parallel; ++s) {52            common_batch_add(batch, tokens[i], i, {s}, false);53        }54    }55    batch.logits[batch.n_tokens - 1] = true;56 57    if (llama_decode(ctx, batch)) {58        fprintf(stderr, "%s : failed to decode seq 0\n", __func__);59        return 1;60    }61 62    fprintf(stderr, "%s : processed prompt on seq 0, 1, 2 (%zu tokens each)\n", __func__, tokens.size());63 64    // Save state of seq 165    std::vector<uint8_t> seq_state(llama_state_seq_get_size(ctx, 1));66    const size_t ncopy = llama_state_seq_get_data(ctx, seq_state.data(), seq_state.size(), 1);67    if (ncopy != seq_state.size()) {68        fprintf(stderr, "%s : failed to save seq 1 state\n", __func__);69        return 1;70    }71    fprintf(stderr, "%s : saved seq 1 state, %zu bytes\n", __func__, ncopy);72 73    // clear seq 1 to create a "hole" in the KV cache (fragmentation)74    // 0.20.20.20.2....75    llama_memory_t mem = llama_get_memory(ctx);76    llama_memory_seq_rm(mem, 1, -1, -1);77    fprintf(stderr, "%s : cleared seq 1 to create fragmentation\n", __func__);78 79    // Now the cache has holes where seq 1 was80    // This creates fragmentation - there's no contiguous block large enough81    // for the seq 1 state if we only look for contiguous slots82 83    // Restore seq 1 state into seq 1 (should work with non-contiguous allocation)84    // We use seq 1 since it's a valid sequence ID (0 to n_parallel-1)85    // Before the fix, this would fail with "failed to find available cells in kv cache"86    const size_t nset = llama_state_seq_set_data(ctx, seq_state.data(), seq_state.size(), 1);87    if (nset != seq_state.size()) {88        fprintf(stderr, "%s : FAILED to restore seq state into fragmented cache (got %zu, expected %zu)\n",89                __func__, nset, seq_state.size());90        fprintf(stderr, "%s : This is the bug - state restore fails with fragmented KV cache\n", __func__);91        llama_batch_free(batch);92        return 1;93    }94    fprintf(stderr, "%s : restored state into seq 1, %zu bytes\n", __func__, nset);95 96    // Verify we can decode with the restored state97    // Generate one token to verify the restored state is usable98    auto sparams = llama_sampler_chain_default_params();99    llama_sampler * smpl = llama_sampler_chain_init(sparams);100    llama_sampler_chain_add(smpl, llama_sampler_init_dist(params.sampling.seed));101 102    auto next_token = llama_sampler_sample(smpl, ctx, -1);103    auto next_token_str = common_token_to_piece(ctx, next_token);104 105    common_batch_clear(batch);106    common_batch_add(batch, next_token, (int)tokens.size(), {1}, true);107 108    if (llama_decode(ctx, batch)) {109        fprintf(stderr, "%s : failed to decode with restored state\n", __func__);110        llama_sampler_free(smpl);111        llama_batch_free(batch);112        return 1;113    }114 115    fprintf(stderr, "%s : successfully decoded with restored state, generated: '%s'\n", __func__, next_token_str.c_str());116    fprintf(stderr, "%s : SUCCESS - state restore works with fragmented KV cache\n", __func__);117 118    llama_sampler_free(smpl);119    llama_batch_free(batch);120 121    return 0;122}123