MIRROR: javascript for 🐜's, a tiny runtime with big ambitions
add arena shrinking and decommit
+35
-14
+27
include/arena.h
+27
include/arena.h
···
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if (base) VirtualFree(base, 0, MEM_RELEASE);
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}
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static inline int ant_arena_decommit(void *base, size_t old_size, size_t new_size) {
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if (new_size >= old_size) return 0;
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void *decommit_start = (char *)base + new_size;
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size_t decommit_size = old_size - new_size;
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return VirtualFree(decommit_start, decommit_size, MEM_DECOMMIT) ? 0 : -1;
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}
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+
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#else
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static inline void *ant_arena_reserve(size_t max_size) {
···
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static inline void ant_arena_free(void *base, size_t reserved_size) {
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if (base) munmap(base, reserved_size);
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}
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static inline int ant_arena_decommit(void *base, size_t old_size, size_t new_size) {
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if (new_size >= old_size) return 0;
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long page_size_long = sysconf(_SC_PAGESIZE);
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if (page_size_long <= 0) return -1;
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size_t page_size = (size_t)page_size_long;
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size_t new_pages = ((new_size + page_size - 1) / page_size) * page_size;
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size_t old_pages = ((old_size + page_size - 1) / page_size) * page_size;
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if (new_pages >= old_pages) return 0;
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void *decommit_start = (char *)base + new_pages;
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size_t decommit_size = old_pages - new_pages;
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if (mprotect(decommit_start, decommit_size, PROT_NONE) == 0) return 0;
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madvise(decommit_start, decommit_size, MADV_DONTNEED);
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return 0;
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}
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#endif
+7
-14
src/gc.c
+7
-14
src/gc.c
···
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gc_scratch_size = 0;
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}
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-
size_t page_size = 4096;
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-
size_t used_pages = (ctx.new_brk + page_size - 1) & ~(page_size - 1);
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+
size_t new_brk = ctx.new_brk;
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size_t old_size = js->size;
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611
-
if (js->size > used_pages) {
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-
size_t release_size = js->size - used_pages;
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-
void *release_start = js->mem + used_pages;
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-
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-
#ifdef _WIN32
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-
VirtualFree(release_start, release_size, MEM_DECOMMIT);
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-
VirtualAlloc(release_start, release_size, MEM_COMMIT, PAGE_READWRITE);
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-
#else
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void *p = mmap(release_start, release_size, PROT_READ | PROT_WRITE, MAP_PRIVATE | MAP_ANON | MAP_FIXED, -1, 0);
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-
if (p == MAP_FAILED) madvise(release_start, release_size, MADV_DONTNEED);
621
-
#endif
611
+
if (new_brk < old_size / 2 && old_size > ARENA_GROW_INCREMENT) {
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size_t target = ((new_brk * 2 + ARENA_GROW_INCREMENT - 1) / ARENA_GROW_INCREMENT) * ARENA_GROW_INCREMENT;
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if (target < ARENA_GROW_INCREMENT) target = ARENA_GROW_INCREMENT;
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if (target < old_size) { ant_arena_decommit(js->mem, old_size, target); js->size = (jsoff_t)target; }
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}
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-
return (old_brk > ctx.new_brk ? old_brk - ctx.new_brk : 0);
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return (old_brk > new_brk ? old_brk - new_brk : 0);
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}
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void js_maybe_gc(ant_t *js) {
+1
tests/bench_gc.js
+1
tests/bench_gc.js
···
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let final = Ant.stats();
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console.log('Final state:');
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console.log(' arenaUsed:', fmt(final.arenaUsed));
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console.log(' arenaSize:', fmt(final.arenaSize));
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console.log(' rss:', fmt(final.rss));
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console.log('');
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console.log('Note: GC runs automatically at safe points.');