hakmem/core/hakmem_policy.c

#include "hakmem_policy.h"
#include <stdlib.h>
#include <string.h>
#include <stdio.h>

static _Atomic(FrozenPolicy*) g_frozen_pol = NULL;

void hkm_policy_init(void) {
    FrozenPolicy* pol = (FrozenPolicy*)calloc(1, sizeof(FrozenPolicy));
    if (!pol) return;

    // Defaults aligned with current implementation
    // Tiny caps: keep placeholders (not enforced in hot path yet)
    pol->tiny_cap[0] = 2048;
    pol->tiny_cap[1] = 1024;
    pol->tiny_cap[2] = 768;
    pol->tiny_cap[3] = 512;
    pol->tiny_cap[4] = 256;
    pol->tiny_cap[5] = 256;
    pol->tiny_cap[6] = 128;
    pol->tiny_cap[7] = 64;

    // ========================================================================
    // CAP初期値の設計思想:
    // ========================================================================
    // 現在の値は「保守的」設定（メモリフットプリント優先）:
    //   - Mid:   {64, 64, 64, 32, 16} → 合計 15.0 MB (64KB/page)
    //   - Large: {8, 8, 4, 2, 1}      → 合計  4.5 MB
    //
    // パフォーマンス優先設定（推奨）:
    //   - Mid:   {256, 256, 256, 128, 64} → 合計 60.0 MB (4倍化)
    //   - Large: {32, 32, 16, 8, 4}       → 合計 18.0 MB (4倍化)
    //
    // トレードオフ:
    //   - CAP大: ヒット率↑、フットプリント↑
    //   - CAP小: ヒット率↓、フットプリント↓
    //
    // 環境変数で変更可能:
    //   HAKMEM_CAP_MID=256,256,256,128,64
    //   HAKMEM_CAP_LARGE=32,32,16,8,4
    // ========================================================================

    // L1: Mid/Large caps – Phase 6.21: Revert to conservative + Bridge classes
    // Phase 2: Mid={256,256,256,128,64} Large={32,32,16,8,4} (4x, 78MB total)
    // Phase 6.21: Mid={64,64,64,32,16,32,32} Large={8,8,4,2,1} (1x + bridges, ~22MB total)
    // Bridge classes (40KB, 52KB) now hardcoded in g_class_sizes[], CAP=32 each
    uint16_t mid_defaults[7]   = { 64, 64, 64, 32, 16, 32, 32 };  // Added slots 5,6 for Bridge
    uint16_t large_defaults[5] = { 8, 8, 4, 2, 1 };               // Reverted to 1x
    memcpy(pol->mid_cap,   mid_defaults,   sizeof(mid_defaults));
    memcpy(pol->large_cap, large_defaults, sizeof(large_defaults));

    // Phase 6.21: Disable DYN1/DYN2 (replaced by hardcoded Bridge classes)
    pol->mid_dyn1_bytes = 0;    // Disabled (Bridge classes now hardcoded)
    pol->mid_cap_dyn1 = 0;
    pol->mid_dyn2_bytes = 0;    // Disabled
    pol->mid_cap_dyn2 = 0;

    // ========================================================================
    // W_MAX (切り上げ許容倍率) の設計思想:
    // ========================================================================
    // W_MAX = 要求サイズの何倍までのクラスを許容するか
    //
    // 現在の値:
    //   - w_max_mid   = 1.40 (40%切り上げ許容) - やや保守的
    //   - w_max_large = 1.30 (30%切り上げ許容) - 保守的 **問題あり**
    //
    // 問題点:
    //   w_max_large=1.30だと、32-64KBギャップで多くの要求が弾かれる
    //   例: 35KB要求 → 64KB使用は 1.83倍 > 1.30 → NG → malloc fallback
    //
    // 推奨値:
    //   - w_max_mid   = 1.40～1.60 (40-60%許容)
    //   - w_max_large = 1.60 (60%許容) ⭐⭐⭐ 即効改善
    //
    // トレードオフ:
    //   - W_MAX大: ヒット率↑、内部断片化↑
    //   - W_MAX小: ヒット率↓、内部断片化↓
    // ========================================================================

    // shard/policy maps default to 0 (noop)
    pol->w_max_mid = 1.60f;    // Phase 6.25: Looser for MidPool performance (was 1.40)
    pol->w_max_large = 1.30f;  // Phase 6.21: Revert to 1.30 (Bridge classes now cover 32-64KB gap)
    pol->w_max = 1.6f;         // legacy aggregate (unused by ACE)
    pol->thp_threshold = 2 * 1024 * 1024; // 2MiB
    pol->generation = 1;

    // Optional env overrides for quick experiments
    const char* e_mid = getenv("HAKMEM_WMAX_MID");
    if (e_mid) {
        float v = (float)atof(e_mid);
        if (v >= 1.0f && v <= 2.0f) pol->w_max_mid = v;
    }
    const char* e_large = getenv("HAKMEM_WMAX_LARGE");
    if (e_large) {
        float v = (float)atof(e_large);
        if (v >= 1.0f && v <= 2.0f) pol->w_max_large = v;
    }

    // Optional CAP overrides: comma-separated integers per class
    const char* cap_mid = getenv("HAKMEM_CAP_MID");
    if (cap_mid) {
        char buf[256]; strncpy(buf, cap_mid, sizeof(buf)-1); buf[sizeof(buf)-1] = '\0';
        char* save = NULL; char* tok = strtok_r(buf, ",", &save); int i=0;
        while (tok && i < 5) { pol->mid_cap[i++] = (uint16_t)atoi(tok); tok = strtok_r(NULL, ",", &save); }
    }
    const char* cap_lg = getenv("HAKMEM_CAP_LARGE");
    if (cap_lg) {
        char buf[256]; strncpy(buf, cap_lg, sizeof(buf)-1); buf[sizeof(buf)-1] = '\0';
        char* save = NULL; char* tok = strtok_r(buf, ",", &save); int i=0;
        while (tok && i < 5) { pol->large_cap[i++] = (uint16_t)atoi(tok); tok = strtok_r(NULL, ",", &save); }
    }

    // Optional dynamic Mid class from env (bytes)
    const char* dyn1 = getenv("HAKMEM_MID_DYN1");
    if (dyn1) {
        long v = atol(dyn1);
        if (v >= 2048 && v <= 32768) pol->mid_dyn1_bytes = (uint32_t)v;
    }

    const char* cap_dyn1 = getenv("HAKMEM_CAP_MID_DYN1");
    if (cap_dyn1) {
        int v = atoi(cap_dyn1);
        if (v >= 0 && v < 65535) pol->mid_cap_dyn1 = (uint16_t)v;
    }

    const char* dyn2 = getenv("HAKMEM_MID_DYN2");
    if (dyn2) {
        long v = atol(dyn2);
        if (v >= 2048 && v <= 32768) pol->mid_dyn2_bytes = (uint32_t)v;
    }
    const char* cap_dyn2 = getenv("HAKMEM_CAP_MID_DYN2");
    if (cap_dyn2) {
        int v = atoi(cap_dyn2);
        if (v >= 0 && v < 65535) pol->mid_cap_dyn2 = (uint16_t)v;
    }

    atomic_store(&g_frozen_pol, pol);
}

void hkm_policy_publish(FrozenPolicy* new_pol) {
    if (!new_pol) return;
    FrozenPolicy* old = atomic_exchange(&g_frozen_pol, new_pol);
    // NOTE: In a real RCU scheme we would wait for a grace period.
    // For now, free the old snapshot immediately.
    free(old);
}

const FrozenPolicy* hkm_policy_get(void) {
    FrozenPolicy* pol = atomic_load(&g_frozen_pol);
    return pol;
}