Add extent serial numbers.
Add extent serial numbers and use them where appropriate as a sort key
that is higher priority than address, so that the allocation policy
prefers older extents.
This resolves #147.
diff --git a/include/jemalloc/internal/arena.h b/include/jemalloc/internal/arena.h
index f518c31..28d63c6 100644
--- a/include/jemalloc/internal/arena.h
+++ b/include/jemalloc/internal/arena.h
@@ -130,7 +130,8 @@
/*
* Heap of non-full slabs. This heap is used to assure that new
- * allocations come from the non-full slab that is lowest in memory.
+ * allocations come from the non-full slab that is oldest/lowest in
+ * memory.
*/
extent_heap_t slabs_nonfull;
@@ -184,6 +185,9 @@
*/
size_t offset_state;
+ /* Extent serial number generator state. */
+ size_t extent_sn_next;
+
dss_prec_t dss_prec;
/* True if a thread is currently executing arena_purge_to_limit(). */
@@ -224,8 +228,8 @@
/* User-configurable extent hook functions. */
union {
- extent_hooks_t *extent_hooks;
- void *extent_hooks_pun;
+ extent_hooks_t *extent_hooks;
+ void *extent_hooks_pun;
};
/* Cache of extent structures that were allocated via base_alloc(). */
@@ -320,6 +324,7 @@
unsigned arena_nthreads_get(arena_t *arena, bool internal);
void arena_nthreads_inc(arena_t *arena, bool internal);
void arena_nthreads_dec(arena_t *arena, bool internal);
+size_t arena_extent_sn_next(arena_t *arena);
arena_t *arena_new(tsdn_t *tsdn, unsigned ind);
void arena_boot(void);
void arena_prefork0(tsdn_t *tsdn, arena_t *arena);
diff --git a/include/jemalloc/internal/extent.h b/include/jemalloc/internal/extent.h
index 531d853..3c5573e 100644
--- a/include/jemalloc/internal/extent.h
+++ b/include/jemalloc/internal/extent.h
@@ -26,6 +26,20 @@
*/
size_t e_usize;
+ /*
+ * Serial number (potentially non-unique).
+ *
+ * In principle serial numbers can wrap around on 32-bit systems if
+ * JEMALLOC_MUNMAP is defined, but as long as comparison functions fall
+ * back on address comparison for equal serial numbers, stable (if
+ * imperfect) ordering is maintained.
+ *
+ * Serial numbers may not be unique even in the absence of wrap-around,
+ * e.g. when splitting an extent and assigning the same serial number to
+ * both resulting adjacent extents.
+ */
+ size_t e_sn;
+
/* True if extent is active (in use). */
bool e_active;
@@ -66,7 +80,7 @@
qr(extent_t) qr_link;
union {
- /* Linkage for per size class address-ordered heaps. */
+ /* Linkage for per size class sn/address-ordered heaps. */
phn(extent_t) ph_link;
/* Linkage for arena's large and extent_cache lists. */
@@ -144,6 +158,7 @@
void *extent_before_get(const extent_t *extent);
void *extent_last_get(const extent_t *extent);
void *extent_past_get(const extent_t *extent);
+size_t extent_sn_get(const extent_t *extent);
bool extent_active_get(const extent_t *extent);
bool extent_retained_get(const extent_t *extent);
bool extent_zeroed_get(const extent_t *extent);
@@ -157,16 +172,20 @@
void extent_addr_randomize(tsdn_t *tsdn, extent_t *extent, size_t alignment);
void extent_size_set(extent_t *extent, size_t size);
void extent_usize_set(extent_t *extent, size_t usize);
+void extent_sn_set(extent_t *extent, size_t sn);
void extent_active_set(extent_t *extent, bool active);
void extent_zeroed_set(extent_t *extent, bool zeroed);
void extent_committed_set(extent_t *extent, bool committed);
void extent_slab_set(extent_t *extent, bool slab);
void extent_prof_tctx_set(extent_t *extent, prof_tctx_t *tctx);
void extent_init(extent_t *extent, arena_t *arena, void *addr,
- size_t size, size_t usize, bool active, bool zeroed, bool committed,
- bool slab);
+ size_t size, size_t usize, size_t sn, bool active, bool zeroed,
+ bool committed, bool slab);
void extent_ring_insert(extent_t *sentinel, extent_t *extent);
void extent_ring_remove(extent_t *extent);
+int extent_sn_comp(const extent_t *a, const extent_t *b);
+int extent_ad_comp(const extent_t *a, const extent_t *b);
+int extent_snad_comp(const extent_t *a, const extent_t *b);
#endif
#if (defined(JEMALLOC_ENABLE_INLINE) || defined(JEMALLOC_EXTENT_C_))
@@ -243,6 +262,13 @@
extent_size_get(extent)));
}
+JEMALLOC_INLINE size_t
+extent_sn_get(const extent_t *extent)
+{
+
+ return (extent->e_sn);
+}
+
JEMALLOC_INLINE bool
extent_active_get(const extent_t *extent)
{
@@ -352,6 +378,13 @@
}
JEMALLOC_INLINE void
+extent_sn_set(extent_t *extent, size_t sn)
+{
+
+ extent->e_sn = sn;
+}
+
+JEMALLOC_INLINE void
extent_active_set(extent_t *extent, bool active)
{
@@ -388,7 +421,8 @@
JEMALLOC_INLINE void
extent_init(extent_t *extent, arena_t *arena, void *addr, size_t size,
- size_t usize, bool active, bool zeroed, bool committed, bool slab)
+ size_t usize, size_t sn, bool active, bool zeroed, bool committed,
+ bool slab)
{
assert(addr == PAGE_ADDR2BASE(addr) || !slab);
@@ -397,6 +431,7 @@
extent_addr_set(extent, addr);
extent_size_set(extent, size);
extent_usize_set(extent, usize);
+ extent_sn_set(extent, sn);
extent_active_set(extent, active);
extent_zeroed_set(extent, zeroed);
extent_committed_set(extent, committed);
@@ -419,6 +454,37 @@
qr_remove(extent, qr_link);
}
+
+JEMALLOC_INLINE int
+extent_sn_comp(const extent_t *a, const extent_t *b)
+{
+ size_t a_sn = extent_sn_get(a);
+ size_t b_sn = extent_sn_get(b);
+
+ return ((a_sn > b_sn) - (a_sn < b_sn));
+}
+
+JEMALLOC_INLINE int
+extent_ad_comp(const extent_t *a, const extent_t *b)
+{
+ uintptr_t a_addr = (uintptr_t)extent_addr_get(a);
+ uintptr_t b_addr = (uintptr_t)extent_addr_get(b);
+
+ return ((a_addr > b_addr) - (a_addr < b_addr));
+}
+
+JEMALLOC_INLINE int
+extent_snad_comp(const extent_t *a, const extent_t *b)
+{
+ int ret;
+
+ ret = extent_sn_comp(a, b);
+ if (ret != 0)
+ return (ret);
+
+ ret = extent_ad_comp(a, b);
+ return (ret);
+}
#endif
#endif /* JEMALLOC_H_INLINES */
diff --git a/include/jemalloc/internal/private_symbols.txt b/include/jemalloc/internal/private_symbols.txt
index 707ede3..4560d70 100644
--- a/include/jemalloc/internal/private_symbols.txt
+++ b/include/jemalloc/internal/private_symbols.txt
@@ -31,6 +31,7 @@
arena_extent_dalloc_large
arena_extent_ralloc_large_expand
arena_extent_ralloc_large_shrink
+arena_extent_sn_next
arena_get
arena_ichoose
arena_init
@@ -132,6 +133,7 @@
dss_prec_names
extent_active_get
extent_active_set
+extent_ad_comp
extent_addr_get
extent_addr_randomize
extent_addr_set
@@ -188,6 +190,10 @@
extent_slab_data_get_const
extent_slab_get
extent_slab_set
+extent_sn_comp
+extent_sn_get
+extent_sn_set
+extent_snad_comp
extent_split_wrapper
extent_usize_get
extent_usize_set
diff --git a/src/arena.c b/src/arena.c
index ef374d3..75a92ed 100644
--- a/src/arena.c
+++ b/src/arena.c
@@ -760,7 +760,7 @@
size_t ndirty = arena_dirty_count(tsdn, arena);
assert(ndirty == arena->ndirty);
}
- extent_init(&purge_extents_sentinel, arena, NULL, 0, 0, false, false,
+ extent_init(&purge_extents_sentinel, arena, NULL, 0, 0, 0, false, false,
false, false);
npurge = arena_stash_dirty(tsdn, arena, &extent_hooks, ndirty_limit,
@@ -1351,12 +1351,12 @@
assert(extent_slab_data_get(slab)->nfree > 0);
/*
- * Make sure that if bin->slabcur is non-NULL, it refers to the lowest
- * non-full slab. It is okay to NULL slabcur out rather than
- * proactively keeping it pointing at the lowest non-full slab.
+ * Make sure that if bin->slabcur is non-NULL, it refers to the
+ * oldest/lowest non-full slab. It is okay to NULL slabcur out rather
+ * than proactively keeping it pointing at the oldest/lowest non-full
+ * slab.
*/
- if (bin->slabcur != NULL && (uintptr_t)extent_addr_get(slab) <
- (uintptr_t)extent_addr_get(bin->slabcur)) {
+ if (bin->slabcur != NULL && extent_snad_comp(bin->slabcur, slab) > 0) {
/* Switch slabcur. */
if (extent_slab_data_get(bin->slabcur)->nfree > 0)
arena_bin_slabs_nonfull_insert(bin, bin->slabcur);
@@ -1651,6 +1651,13 @@
atomic_sub_u(&arena->nthreads[internal], 1);
}
+size_t
+arena_extent_sn_next(arena_t *arena)
+{
+
+ return (atomic_add_zu(&arena->extent_sn_next, 1) - 1);
+}
+
arena_t *
arena_new(tsdn_t *tsdn, unsigned ind)
{
@@ -1684,6 +1691,8 @@
(size_t)(uintptr_t)arena;
}
+ arena->extent_sn_next = 0;
+
arena->dss_prec = extent_dss_prec_get();
arena->purging = false;
@@ -1702,7 +1711,7 @@
extent_heap_new(&arena->extents_retained[i]);
}
- extent_init(&arena->extents_dirty, arena, NULL, 0, 0, false, false,
+ extent_init(&arena->extents_dirty, arena, NULL, 0, 0, 0, false, false,
false, false);
if (malloc_mutex_init(&arena->extents_mtx, "arena_extents",
@@ -1724,8 +1733,8 @@
return (NULL);
bin->slabcur = NULL;
extent_heap_new(&bin->slabs_nonfull);
- extent_init(&bin->slabs_full, arena, NULL, 0, 0, false, false,
- false, false);
+ extent_init(&bin->slabs_full, arena, NULL, 0, 0, 0, false,
+ false, false, false);
if (config_stats)
memset(&bin->stats, 0, sizeof(malloc_bin_stats_t));
}
diff --git a/src/base.c b/src/base.c
index 9c3f36c..4764d9c 100644
--- a/src/base.c
+++ b/src/base.c
@@ -5,6 +5,7 @@
/* Data. */
static malloc_mutex_t base_mtx;
+static size_t base_extent_sn_next;
static extent_heap_t base_avail[NSIZES];
static extent_t *base_extents;
static size_t base_allocated;
@@ -37,6 +38,14 @@
base_extents = extent;
}
+static void
+base_extent_init(extent_t *extent, void *addr, size_t size)
+{
+ size_t sn = atomic_add_zu(&base_extent_sn_next, 1) - 1;
+
+ extent_init(extent, NULL, addr, size, 0, sn, true, true, true, false);
+}
+
static extent_t *
base_extent_alloc(tsdn_t *tsdn, size_t minsize)
{
@@ -74,7 +83,7 @@
base_resident += PAGE_CEILING(nsize);
}
}
- extent_init(extent, NULL, addr, esize, 0, true, true, true, false);
+ base_extent_init(extent, addr, esize);
return (extent);
}
@@ -164,6 +173,7 @@
if (malloc_mutex_init(&base_mtx, "base", WITNESS_RANK_BASE))
return (true);
+ base_extent_sn_next = 0;
for (i = 0; i < NSIZES; i++)
extent_heap_new(&base_avail[i]);
base_extents = NULL;
diff --git a/src/extent.c b/src/extent.c
index 34ac63e..be6cadc 100644
--- a/src/extent.c
+++ b/src/extent.c
@@ -177,17 +177,8 @@
JEMALLOC_N(n_extent_size_quantize_ceil);
#endif
-JEMALLOC_INLINE_C int
-extent_ad_comp(const extent_t *a, const extent_t *b)
-{
- uintptr_t a_addr = (uintptr_t)extent_addr_get(a);
- uintptr_t b_addr = (uintptr_t)extent_addr_get(b);
-
- return ((a_addr > b_addr) - (a_addr < b_addr));
-}
-
/* Generate pairing heap functions. */
-ph_gen(, extent_heap_, extent_heap_t, extent_t, ph_link, extent_ad_comp)
+ph_gen(, extent_heap_, extent_heap_t, extent_t, ph_link, extent_snad_comp)
static void
extent_heaps_insert(tsdn_t *tsdn, extent_heap_t extent_heaps[NPSIZES+1],
@@ -353,8 +344,8 @@
}
/*
- * Do first-best-fit extent selection, i.e. select the lowest extent that best
- * fits.
+ * Do first-best-fit extent selection, i.e. select the oldest/lowest extent that
+ * best fits.
*/
static extent_t *
extent_first_best_fit(tsdn_t *tsdn, arena_t *arena,
@@ -708,7 +699,8 @@
extent_dalloc(tsdn, arena, extent);
return (NULL);
}
- extent_init(extent, arena, addr, size, usize, true, zero, commit, slab);
+ extent_init(extent, arena, addr, size, usize,
+ arena_extent_sn_next(arena), true, zero, commit, slab);
if (pad != 0)
extent_addr_randomize(tsdn, extent, alignment);
if (extent_register(tsdn, extent)) {
@@ -1036,7 +1028,7 @@
extent_t lead;
extent_init(&lead, arena, extent_addr_get(extent), size_a,
- usize_a, extent_active_get(extent),
+ usize_a, extent_sn_get(extent), extent_active_get(extent),
extent_zeroed_get(extent), extent_committed_get(extent),
extent_slab_get(extent));
@@ -1046,9 +1038,9 @@
}
extent_init(trail, arena, (void *)((uintptr_t)extent_base_get(extent) +
- size_a), size_b, usize_b, extent_active_get(extent),
- extent_zeroed_get(extent), extent_committed_get(extent),
- extent_slab_get(extent));
+ size_a), size_b, usize_b, extent_sn_get(extent),
+ extent_active_get(extent), extent_zeroed_get(extent),
+ extent_committed_get(extent), extent_slab_get(extent));
if (extent_rtree_acquire(tsdn, rtree_ctx, trail, false, true,
&trail_elm_a, &trail_elm_b))
goto label_error_c;
@@ -1145,6 +1137,8 @@
extent_size_set(a, extent_size_get(a) + extent_size_get(b));
extent_usize_set(a, extent_usize_get(a) + extent_usize_get(b));
+ extent_sn_set(a, (extent_sn_get(a) < extent_sn_get(b)) ?
+ extent_sn_get(a) : extent_sn_get(b));
extent_zeroed_set(a, extent_zeroed_get(a) && extent_zeroed_get(b));
extent_rtree_write_acquired(tsdn, a_elm_a, b_elm_b, a);
diff --git a/src/extent_dss.c b/src/extent_dss.c
index 31fe8fe..1169d49 100644
--- a/src/extent_dss.c
+++ b/src/extent_dss.c
@@ -142,7 +142,8 @@
gap_size = (uintptr_t)ret - (uintptr_t)gap_addr;
if (gap_size != 0) {
extent_init(gap, arena, gap_addr, gap_size,
- gap_size, false, false, true, false);
+ gap_size, arena_extent_sn_next(arena),
+ false, false, true, false);
}
dss_next = (void *)((uintptr_t)ret + size);
if ((uintptr_t)ret < (uintptr_t)max_cur ||
