SEC: Allow arbitrarily many shards, cached sizes.

include/jemalloc/internal/pa.h

@@ -130,8 +130,8 @@ bool pa_shard_init(tsdn_t *tsdn, pa_shard_t *shard, emap_t *emap, base_t *base,
  * This isn't exposed to users; we allow late enablement of the HPA shard so
  * that we can boot without worrying about the HPA, then turn it on in a0.
  */
-bool pa_shard_enable_hpa(pa_shard_t *shard, const hpa_shard_opts_t *hpa_opts,
-    const sec_opts_t *hpa_sec_opts);
+bool pa_shard_enable_hpa(tsdn_t *tsdn, pa_shard_t *shard,
+    const hpa_shard_opts_t *hpa_opts, const sec_opts_t *hpa_sec_opts);
 /*
  * We stop using the HPA when custom extent hooks are installed, but still
  * redirect deallocations to it.

include/jemalloc/internal/sec.h

@@ -13,20 +13,6 @@
  * knowledge of the underlying PAI implementation).
  */
 
-/*
- * This is a *small* extent cache, after all.  Assuming 4k pages and an ngroup
- * of 4, this allows caching of sizes up to 128k.
- */
-#define SEC_NPSIZES 16
-/*
- * For now, we put a cap on the number of SECs an arena can have.  There's no
- * reason it can't be dynamic; it's just inconvenient.  This number of shards
- * are embedded in the arenas, so there's a space / configurability tradeoff
- * here.  Eventually, we should probably dynamically allocate only however many
- * we require.
- */
-#define SEC_NSHARDS_MAX 8
-
 /*
  * For now, this is just one field; eventually, we'll probably want to get more
  * fine-grained data out (like per-size class statistics).
@@ -91,7 +77,7 @@ struct sec_shard_s {
 	 * hooks are installed.
 	 */
 	bool enabled;
-	sec_bin_t bins[SEC_NPSIZES];
+	sec_bin_t *bins;
 	/* Number of bytes in all bins in the shard. */
 	size_t bytes_cur;
 	/* The next pszind to flush in the flush-some pathways. */
@@ -104,10 +90,12 @@ struct sec_s {
 	pai_t *fallback;
 
 	sec_opts_t opts;
-	sec_shard_t shards[SEC_NSHARDS_MAX];
+	sec_shard_t *shards;
+	pszind_t npsizes;
 };
 
-bool sec_init(sec_t *sec, pai_t *fallback, const sec_opts_t *opts);
+bool sec_init(tsdn_t *tsdn, sec_t *sec, base_t *base, pai_t *fallback,
+    const sec_opts_t *opts);
 void sec_flush(tsdn_t *tsdn, sec_t *sec);
 void sec_disable(tsdn_t *tsdn, sec_t *sec);
 

src/arena.c

@@ -1565,7 +1565,7 @@ arena_new(tsdn_t *tsdn, unsigned ind, extent_hooks_t *extent_hooks) {
 	 *   so arena_hpa_global is not yet initialized.
 	 */
 	if (opt_hpa && ehooks_are_default(base_ehooks_get(base)) && ind != 0) {
-		if (pa_shard_enable_hpa(&arena->pa_shard, &opt_hpa_opts,
+		if (pa_shard_enable_hpa(tsdn, &arena->pa_shard, &opt_hpa_opts,
 		    &opt_hpa_sec_opts)) {
 			goto label_error;
 		}

src/jemalloc.c

@@ -1781,7 +1781,7 @@ malloc_init_hard_a0_locked() {
 			opt_hpa = false;
 		}
 	} else if (opt_hpa) {
-		if (pa_shard_enable_hpa(&a0->pa_shard, &opt_hpa_opts,
+		if (pa_shard_enable_hpa(TSDN_NULL, &a0->pa_shard, &opt_hpa_opts,
 		    &opt_hpa_sec_opts)) {
 			return true;
 		}

src/pa.c

@@ -49,13 +49,14 @@ pa_shard_init(tsdn_t *tsdn, pa_shard_t *shard, emap_t *emap, base_t *base,
 }
 
 bool
-pa_shard_enable_hpa(pa_shard_t *shard, const hpa_shard_opts_t *hpa_opts,
-    const sec_opts_t *hpa_sec_opts) {
+pa_shard_enable_hpa(tsdn_t *tsdn, pa_shard_t *shard,
+    const hpa_shard_opts_t *hpa_opts, const sec_opts_t *hpa_sec_opts) {
 	if (hpa_shard_init(&shard->hpa_shard, shard->emap, shard->base,
 	    &shard->edata_cache, shard->ind, hpa_opts)) {
 		return true;
 	}
-	if (sec_init(&shard->hpa_sec, &shard->hpa_shard.pai, hpa_sec_opts)) {
+	if (sec_init(tsdn, &shard->hpa_sec, shard->base, &shard->hpa_shard.pai,
+	    hpa_sec_opts)) {
 		return true;
 	}
 	shard->ever_used_hpa = true;

src/sec.c

@@ -19,35 +19,55 @@ sec_bin_init(sec_bin_t *bin) {
 }
 
 bool
-sec_init(sec_t *sec, pai_t *fallback, const sec_opts_t *opts) {
-	size_t nshards_clipped = opts->nshards;
-	if (nshards_clipped > SEC_NSHARDS_MAX) {
-		nshards_clipped = SEC_NSHARDS_MAX;
+sec_init(tsdn_t *tsdn, sec_t *sec, base_t *base, pai_t *fallback,
+    const sec_opts_t *opts) {
+	size_t max_alloc = opts->max_alloc & PAGE_MASK;
+	pszind_t npsizes = sz_psz2ind(max_alloc);
+	if (sz_pind2sz(npsizes) > opts->max_alloc) {
+		npsizes--;
 	}
-	for (size_t i = 0; i < nshards_clipped; i++) {
-		sec_shard_t *shard = &sec->shards[i];
+	size_t sz_shards = opts->nshards * sizeof(sec_shard_t);
+	size_t sz_bins = opts->nshards * (size_t)npsizes * sizeof(sec_bin_t);
+	size_t sz_alloc = sz_shards + sz_bins;
+	void *dynalloc = base_alloc(tsdn, base, sz_alloc, CACHELINE);
+	if (dynalloc == NULL) {
+		return true;
+	}
+	sec_shard_t *shard_cur = (sec_shard_t *)dynalloc;
+	sec->shards = shard_cur;
+	sec_bin_t *bin_cur = (sec_bin_t *)&shard_cur[opts->nshards];
+	/* Just for asserts, below. */
+	sec_bin_t *bin_start = bin_cur;
+
+	for (size_t i = 0; i < opts->nshards; i++) {
+		sec_shard_t *shard = shard_cur;
+		shard_cur++;
 		bool err = malloc_mutex_init(&shard->mtx, "sec_shard",
 		    WITNESS_RANK_SEC_SHARD, malloc_mutex_rank_exclusive);
 		if (err) {
 			return true;
 		}
 		shard->enabled = true;
-		for (pszind_t j = 0; j < SEC_NPSIZES; j++) {
+		shard->bins = bin_cur;
+		for (pszind_t j = 0; j < npsizes; j++) {
 			sec_bin_init(&shard->bins[j]);
+			bin_cur++;
 		}
 		shard->bytes_cur = 0;
 		shard->to_flush_next = 0;
 	}
+	/*
+	 * Should have exactly matched the bin_start to the first unused byte
+	 * after the shards.
+	 */
+	assert((void *)shard_cur == (void *)bin_start);
+	/* And the last bin to use up the last bytes of the allocation. */
+	assert((char *)bin_cur == ((char *)dynalloc + sz_alloc));
 	sec->fallback = fallback;
 
-	size_t max_alloc_clipped = opts->max_alloc;
-	if (max_alloc_clipped > sz_pind2sz(SEC_NPSIZES - 1)) {
-		max_alloc_clipped = sz_pind2sz(SEC_NPSIZES - 1);
-	}
 
 	sec->opts = *opts;
-	sec->opts.nshards = nshards_clipped;
-	sec->opts.max_alloc = max_alloc_clipped;
+	sec->npsizes = npsizes;
 
 	/*
 	 * Initialize these last so that an improper use of an SEC whose
@@ -106,7 +126,7 @@ sec_flush_some_and_unlock(tsdn_t *tsdn, sec_t *sec, sec_shard_t *shard) {
 
 		/* Update our victim-picking state. */
 		shard->to_flush_next++;
-		if (shard->to_flush_next == SEC_NPSIZES) {
+		if (shard->to_flush_next == sec->npsizes) {
 			shard->to_flush_next = 0;
 		}
 
@@ -249,7 +269,7 @@ sec_flush_all_locked(tsdn_t *tsdn, sec_t *sec, sec_shard_t *shard) {
 	shard->bytes_cur = 0;
 	edata_list_active_t to_flush;
 	edata_list_active_init(&to_flush);
-	for (pszind_t i = 0; i < SEC_NPSIZES; i++) {
+	for (pszind_t i = 0; i < sec->npsizes; i++) {
 		sec_bin_t *bin = &shard->bins[i];
 		bin->bytes_cur = 0;
 		edata_list_active_concat(&to_flush, &bin->freelist);

test/unit/sec.c

@@ -37,7 +37,14 @@ test_sec_init(sec_t *sec, pai_t *fallback, size_t nshards, size_t max_alloc,
 	opts.bytes_after_flush = max_bytes / 2;
 	opts.batch_fill_extra = 4;
 
-	bool err = sec_init(sec, fallback, &opts);
+	/*
+	 * We end up leaking this base, but that's fine; this test is
+	 * short-running, and SECs are arena-scoped in reality.
+	 */
+	base_t *base = base_new(TSDN_NULL, /* ind */ 123,
+	    &ehooks_default_extent_hooks);
+
+	bool err = sec_init(TSDN_NULL, sec, base, fallback, &opts);
 	assert_false(err, "Unexpected initialization failure");
 }
 
@@ -412,10 +419,12 @@ TEST_BEGIN(test_nshards_0) {
 	sec_t sec;
 	/* See the note above -- we can't use the real tsd. */
 	tsdn_t *tsdn = TSDN_NULL;
+	base_t *base = base_new(TSDN_NULL, /* ind */ 123,
+	    &ehooks_default_extent_hooks);
 
 	sec_opts_t opts = SEC_OPTS_DEFAULT;
 	opts.nshards = 0;
-	sec_init(&sec, &ta.pai, &opts);
+	sec_init(TSDN_NULL, &sec, base, &ta.pai, &opts);
 
 	edata_t *edata = pai_alloc(tsdn, &sec.pai, PAGE, PAGE,
 	    /* zero */ false);