78 lines
2.4 KiB
C
78 lines
2.4 KiB
C
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// ss_release_policy_box.c - SuperSlab Release Policy Box Implementation
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#include "ss_release_policy_box.h"
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#include "ss_mem_lean_env_box.h"
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#include "madvise_guard_box.h"
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#include "ss_os_acquire_box.h"
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#include "../superslab/superslab_types.h"
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#include <sys/mman.h>
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#include <errno.h>
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// ============================================================================
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// Release Policy Implementation
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// ============================================================================
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bool ss_should_keep_superslab(SuperSlab* ss, int class_idx) {
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(void)ss; // Reserved for future budget logic
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(void)class_idx; // Reserved for per-class policy
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// In lean mode: allow release of empty superslabs
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// In FAST mode (default): keep all superslabs (persistent backend)
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if (ss_mem_lean_enabled()) {
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// TODO: Add per-class budget logic here if needed
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// For now: allow release (caller decides based on empty state)
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return false; // Signal: OK to release in lean mode
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}
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// Default (FAST mode): keep all superslabs (speed-first)
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return true;
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}
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int ss_maybe_decommit_superslab(void* ptr, size_t size) {
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// Fast path: lean mode disabled → no-op
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if (!ss_mem_lean_enabled()) {
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return 0;
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}
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// Get decommit mode from ENV
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ss_mem_lean_decommit_mode_t mode = ss_mem_lean_decommit_mode();
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// If decommit is OFF, skip (only prewarm suppression active)
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if (mode == SS_MEM_LEAN_DECOMMIT_OFF) {
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return 0;
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}
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// Select madvise advice based on mode
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int advice;
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switch (mode) {
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case SS_MEM_LEAN_DECOMMIT_FREE:
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#ifdef MADV_FREE
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advice = MADV_FREE; // Lazy reclaim (fast, kernel 4.5+)
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#else
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// Fallback to MADV_DONTNEED if MADV_FREE not available
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advice = MADV_DONTNEED;
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#endif
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break;
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case SS_MEM_LEAN_DECOMMIT_DONTNEED:
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advice = MADV_DONTNEED; // Eager reclaim (slower, but universal)
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break;
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default:
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return 0; // Unknown mode, skip
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}
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// Call DSO-guarded madvise (respects guard rules)
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// This will:
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// - Skip if ptr overlaps DSO (.fini_array safety)
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// - Disable future calls on ENOMEM (fail-fast)
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// - Update madvise counters
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int ret = ss_os_madvise_guarded(ptr, size, advice, "ss_release_policy_decommit");
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if (ret == 0) {
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// Success: update lean_decommit counter
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ss_os_stats_record_lean_decommit();
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}
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return ret;
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}
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