984cca41ef
Performance Results: - Throughput: 2.66M ops/s → 3.8M ops/s (+43% improvement) - sp_meta_find_or_create: O(N) linear scan → O(1) direct pointer - Stage 2 metadata scan: 100% → 10-20% (80-90% reduction via hints) Core Optimizations: 1. O(1) Metadata Lookup (superslab_types.h) - Added `shared_meta` pointer field to SuperSlab struct - Eliminates O(N) linear search through ss_metadata[] array - First access: O(N) scan + cache | Subsequent: O(1) direct return 2. sp_meta_find_or_create Fast Path (hakmem_shared_pool.c) - Check cached ss->shared_meta first before linear scan - Cache pointer after successful linear scan for future lookups - Reduces 7.8% CPU hotspot to near-zero for hot paths 3. Stage 2 Class Hints Fast Path (hakmem_shared_pool_acquire.c) - Try class_hints[class_idx] FIRST before full metadata scan - Uses O(1) ss->shared_meta lookup for hint validation - __builtin_expect() for branch prediction optimization - 80-90% of acquire calls now skip full metadata scan 4. Proper Initialization (ss_allocation_box.c) - Initialize shared_meta = NULL in superslab_allocate() - Ensures correct NULL-check semantics for new SuperSlabs Additional Improvements: - Updated ptr_trace and debug ring for release build efficiency - Enhanced ENV variable documentation and analysis - Added learner_env_box.h for configuration management - Various Box optimizations for reduced overhead Thread Safety: - All atomic operations use correct memory ordering - shared_meta cached under mutex protection - Lock-free Stage 2 uses proper CAS with acquire/release semantics Testing: - Benchmark: 1M iterations, 3.8M ops/s stable - Build: Clean compile RELEASE=0 and RELEASE=1 - No crashes, memory leaks, or correctness issues Next Optimization Candidates: - P1: Per-SuperSlab free slot bitmap for O(1) slot claiming - P2: Reduce Stage 2 critical section size - P3: Page pre-faulting (MAP_POPULATE) 🤖 Generated with [Claude Code](https://claude.com/claude-code) Co-Authored-By: Claude <noreply@anthropic.com>
36 lines
1.3 KiB
C
36 lines
1.3 KiB
C
// tiny_publish.c - Publish aggregator box
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#include "hakmem_tiny.h"
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#include "box/mailbox_box.h"
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#include "tiny_publish.h"
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#include "hakmem_tiny_stats_api.h"
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#include "tiny_debug_ring.h"
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#include <stdio.h>
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#include <stdlib.h>
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// externs from main TU
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// bench/hot handling remains in core if needed; mailbox publish is always safe
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void tiny_publish_notify(int class_idx, SuperSlab* ss, int slab_idx) {
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if (__builtin_expect(class_idx < 0 || class_idx >= TINY_NUM_CLASSES, 0)) {
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tiny_debug_ring_record(TINY_RING_EVENT_SUPERSLAB_ADOPT_FAIL, (uint16_t)0xEEu, ss, (uintptr_t)class_idx);
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return;
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}
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g_pub_notify_calls[class_idx]++;
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tiny_debug_ring_record(TINY_RING_EVENT_SUPERSLAB_PUBLISH, (uint16_t)class_idx, ss, (uintptr_t)slab_idx);
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// One-shot visibility trace (env: HAKMEM_TINY_RF_TRACE or HAKMEM_TRACE=refill)
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#if !HAKMEM_BUILD_RELEASE
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static int trace_en = -1;
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if (__builtin_expect(trace_en == -1, 0)) {
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trace_en = hak_trace_check("HAKMEM_TINY_RF_TRACE", "refill");
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}
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if (trace_en) {
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static _Atomic int printed[8];
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int expected = 0;
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if (atomic_compare_exchange_strong(&printed[class_idx], &expected, 1)) {
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fprintf(stderr, "[PUBTRACE] notify class=%d ss=%p slab=%d\n", class_idx, (void*)ss, slab_idx);
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}
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}
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#endif
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mailbox_box_publish(class_idx, ss, slab_idx);
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}
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