hakmem/core/box/ss_hot_prewarm_box.c

// ss_hot_prewarm_box.c - Box SS-HotPrewarm Implementation
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include "../hakmem_tiny.h"       // MUST BE FIRST: Base types
#include "../hakmem_tiny_config.h" // TINY_NUM_CLASSES
#include "ss_hot_prewarm_box.h"
#include "prewarm_box.h"          // box_prewarm_tls()

// Per-class prewarm targets (cached from ENV)
static int g_ss_hot_prewarm_targets[TINY_NUM_CLASSES] = {0};
static int g_ss_hot_prewarm_initialized = 0;

// Default aggressive targets (ChatGPT Phase 20 strategy)
// Classes 0-1 (tiny): 0 (no prewarm)
// Classes 2-3 (33-128B): 128 blocks (hot path)
// Classes 4-5 (129-512B): 64 blocks (medium hot)
// Classes 6-7 (513-1024B): 0 (rare)
static const int g_ss_hot_prewarm_defaults[TINY_NUM_CLASSES] = {
    0,    // C0 (16B) - not used
    0,    // C1 (17-32B) - not used
    128,  // C2 (33-64B) - HOT
    128,  // C3 (65-128B) - HOT
    64,   // C4 (129-256B) - MEDIUM
    64,   // C5 (257-512B) - MEDIUM
    0,    // C6 (513-1024B) - rare
    0     // C7 (1024B) - rare
};

// ============================================================================
// Internal Helpers
// ============================================================================

static void ss_hot_prewarm_init_targets(void) {
    if (g_ss_hot_prewarm_initialized) return;

    // Step 1: Copy defaults
    for (int i = 0; i < TINY_NUM_CLASSES; i++) {
        g_ss_hot_prewarm_targets[i] = g_ss_hot_prewarm_defaults[i];
    }

    // Step 2: Check for global override
    const char* all_env = getenv("HAKMEM_TINY_PREWARM_ALL");
    if (all_env && *all_env) {
        int all_count = atoi(all_env);
        if (all_count >= 0) {
            for (int i = 0; i < TINY_NUM_CLASSES; i++) {
                g_ss_hot_prewarm_targets[i] = all_count;
            }
            #if !HAKMEM_BUILD_RELEASE
            fprintf(stderr, "[BOX_SS_HOT_PREWARM] Global override: HAKMEM_TINY_PREWARM_ALL=%d\n", all_count);
            #endif
        }
    }

    // Step 3: Parse per-class ENV overrides
    const char* class_env_names[TINY_NUM_CLASSES] = {
        "HAKMEM_TINY_PREWARM_C0",
        "HAKMEM_TINY_PREWARM_C1",
        "HAKMEM_TINY_PREWARM_C2",
        "HAKMEM_TINY_PREWARM_C3",
        "HAKMEM_TINY_PREWARM_C4",
        "HAKMEM_TINY_PREWARM_C5",
        "HAKMEM_TINY_PREWARM_C6",
        "HAKMEM_TINY_PREWARM_C7"
    };

    for (int i = 0; i < TINY_NUM_CLASSES; i++) {
        const char* env = getenv(class_env_names[i]);
        if (env && *env) {
            int count = atoi(env);
            if (count >= 0) {
                g_ss_hot_prewarm_targets[i] = count;
                #if !HAKMEM_BUILD_RELEASE
                fprintf(stderr, "[BOX_SS_HOT_PREWARM] Class %d override: %s=%d\n",
                        i, class_env_names[i], count);
                #endif
            }
        }
    }

    // Step 4: Report final configuration (debug only)
    #if !HAKMEM_BUILD_RELEASE
    fprintf(stderr, "[BOX_SS_HOT_PREWARM] Final targets: ");
    for (int i = 0; i < TINY_NUM_CLASSES; i++) {
        if (g_ss_hot_prewarm_targets[i] > 0) {
            fprintf(stderr, "C%d=%d ", i, g_ss_hot_prewarm_targets[i]);
        }
    }
    fprintf(stderr, "\n");
    #endif

    g_ss_hot_prewarm_initialized = 1;
}

// ============================================================================
// Public API
// ============================================================================

int box_ss_hot_prewarm_target(int class_idx) {
    if (class_idx < 0 || class_idx >= TINY_NUM_CLASSES) return 0;

    if (!g_ss_hot_prewarm_initialized) {
        ss_hot_prewarm_init_targets();
    }

    return g_ss_hot_prewarm_targets[class_idx];
}

int box_ss_hot_prewarm_all(void) {
    // Initialize targets from ENV
    ss_hot_prewarm_init_targets();

    int total_prewarmed = 0;

    // Prewarm each class with non-zero target
    for (int class_idx = 0; class_idx < TINY_NUM_CLASSES; class_idx++) {
        int target = g_ss_hot_prewarm_targets[class_idx];
        if (target <= 0) continue;

        #if !HAKMEM_BUILD_RELEASE
        fprintf(stderr, "[BOX_SS_HOT_PREWARM] Prewarming C%d with %d blocks...\n",
                class_idx, target);
        #endif

        // Use Box Prewarm API to safely warm TLS SLL
        // This will automatically:
        // - Allocate SuperSlab if needed
        // - Populate pages (touch memory)
        // - Fill TLS SLL with blocks
        int actual = box_prewarm_tls(class_idx, target);

        #if !HAKMEM_BUILD_RELEASE
        if (actual < target) {
            fprintf(stderr, "[BOX_SS_HOT_PREWARM] C%d: requested=%d actual=%d (capacity limited)\n",
                    class_idx, target, actual);
        }
        #endif

        total_prewarmed += actual;
    }

    // Phase 20-1: Log prewarm summary (DEBUG ONLY to avoid perf impact)
#if !HAKMEM_BUILD_RELEASE
    fprintf(stderr, "[BOX_SS_HOT_PREWARM] Total blocks pre-warmed: %d\n", total_prewarmed);
#endif

    return total_prewarmed;
}