Add arena.i.retain_grow_limit

This option controls the max size when grow_retained.  This is useful when we
have customized extent hooks reserving physical memory (e.g. 1G huge pages).
Without this feature, the default increasing sequence could result in fragmented
and wasted physical memory.

doc/jemalloc.xml.in

@@ -1683,6 +1683,22 @@ malloc_conf = "xmalloc:true";]]></programlisting>
         for additional information.</para></listitem>
       </varlistentry>
 
+      <varlistentry id="arena.i.retain_grow_limit">
+        <term>
+          <mallctl>arena.&lt;i&gt;.retain_grow_limit</mallctl>
+          (<type>size_t</type>)
+          <literal>rw</literal>
+        </term>
+        <listitem><para>Maximum size to grow retained region (only relevant when
+        <link linkend="opt.retain"><mallctl>opt.retain</mallctl></link> is
+        enabled).  This controls the maximum increment to expand virtual memory,
+        or allocation through <link
+        linkend="arena.i.extent_hooks"><mallctl>arena.&lt;i&gt;extent_hooks</mallctl></link>.
+        In particular, if customized extent hooks reserve physical memory
+        (e.g. 1G huge pages), this is useful to control the allocation hook's
+        input size.  The default is no limit.</para></listitem>
+      </varlistentry>
+
       <varlistentry id="arena.i.extent_hooks">
         <term>
           <mallctl>arena.&lt;i&gt;.extent_hooks</mallctl>

include/jemalloc/internal/arena_externs.h

@@ -77,6 +77,8 @@ ssize_t arena_dirty_decay_ms_default_get(void);
 bool arena_dirty_decay_ms_default_set(ssize_t decay_ms);
 ssize_t arena_muzzy_decay_ms_default_get(void);
 bool arena_muzzy_decay_ms_default_set(ssize_t decay_ms);
+bool arena_retain_grow_limit_get_set(tsd_t *tsd, arena_t *arena,
+    size_t *old_limit, size_t *new_limit);
 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);

include/jemalloc/internal/arena_structs_b.h

@@ -240,9 +240,14 @@ struct arena_s {
 	 * be effective even if multiple arenas' extent allocation requests are
 	 * highly interleaved.
 	 *
+	 * retain_grow_limit is the max allowed size ind to expand (unless the
+	 * required size is greater).  Default is no limit, and controlled
+	 * through mallctl only.
+	 *
 	 * Synchronization: extent_grow_mtx
 	 */
 	pszind_t		extent_grow_next;
+	pszind_t		retain_grow_limit;
 	malloc_mutex_t		extent_grow_mtx;
 
 	/*

include/jemalloc/internal/extent_types.h

@@ -6,4 +6,6 @@ typedef struct extents_s extents_t;
 
 #define EXTENT_HOOKS_INITIALIZER	NULL
 
+#define EXTENT_GROW_MAX_PIND (NPSIZES - 1)
+
 #endif /* JEMALLOC_INTERNAL_EXTENT_TYPES_H */

src/arena.c

@@ -1886,6 +1886,33 @@ arena_muzzy_decay_ms_default_set(ssize_t decay_ms) {
 	return false;
 }
 
+bool
+arena_retain_grow_limit_get_set(tsd_t *tsd, arena_t *arena, size_t *old_limit,
+    size_t *new_limit) {
+	assert(opt_retain);
+
+	pszind_t new_ind JEMALLOC_CC_SILENCE_INIT(0);
+	if (new_limit != NULL) {
+		size_t limit = *new_limit;
+		/* Grow no more than the new limit. */
+		if ((new_ind = sz_psz2ind(limit + 1) - 1) >
+		     EXTENT_GROW_MAX_PIND) {
+			return true;
+		}
+	}
+
+	malloc_mutex_lock(tsd_tsdn(tsd), &arena->extent_grow_mtx);
+	if (old_limit != NULL) {
+		*old_limit = sz_pind2sz(arena->retain_grow_limit);
+	}
+	if (new_limit != NULL) {
+		arena->retain_grow_limit = new_ind;
+	}
+	malloc_mutex_unlock(tsd_tsdn(tsd), &arena->extent_grow_mtx);
+
+	return false;
+}
+
 unsigned
 arena_nthreads_get(arena_t *arena, bool internal) {
 	return atomic_load_u(&arena->nthreads[internal], ATOMIC_RELAXED);
@@ -2013,6 +2040,7 @@ arena_new(tsdn_t *tsdn, unsigned ind, extent_hooks_t *extent_hooks) {
 	}
 
 	arena->extent_grow_next = sz_psz2ind(HUGEPAGE);
+	arena->retain_grow_limit = EXTENT_GROW_MAX_PIND;
 	if (malloc_mutex_init(&arena->extent_grow_mtx, "extent_grow",
 	    WITNESS_RANK_EXTENT_GROW, malloc_mutex_rank_exclusive)) {
 		goto label_error;

src/ctl.c

@@ -118,6 +118,7 @@ CTL_PROTO(arena_i_dss)
 CTL_PROTO(arena_i_dirty_decay_ms)
 CTL_PROTO(arena_i_muzzy_decay_ms)
 CTL_PROTO(arena_i_extent_hooks)
+CTL_PROTO(arena_i_retain_grow_limit)
 INDEX_PROTO(arena_i)
 CTL_PROTO(arenas_bin_i_size)
 CTL_PROTO(arenas_bin_i_nregs)
@@ -320,7 +321,8 @@ static const ctl_named_node_t arena_i_node[] = {
 	{NAME("dss"),		CTL(arena_i_dss)},
 	{NAME("dirty_decay_ms"), CTL(arena_i_dirty_decay_ms)},
 	{NAME("muzzy_decay_ms"), CTL(arena_i_muzzy_decay_ms)},
-	{NAME("extent_hooks"),	CTL(arena_i_extent_hooks)}
+	{NAME("extent_hooks"),	CTL(arena_i_extent_hooks)},
+	{NAME("retain_grow_limit"),	CTL(arena_i_retain_grow_limit)}
 };
 static const ctl_named_node_t super_arena_i_node[] = {
 	{NAME(""),		CHILD(named, arena_i)}
@@ -2199,6 +2201,42 @@ label_return:
 	return ret;
 }
 
+static int
+arena_i_retain_grow_limit_ctl(tsd_t *tsd, const size_t *mib, size_t miblen,
+    void *oldp, size_t *oldlenp, void *newp, size_t newlen) {
+	int ret;
+	unsigned arena_ind;
+	arena_t *arena;
+
+	if (!opt_retain) {
+		/* Only relevant when retain is enabled. */
+		return ENOENT;
+	}
+
+	malloc_mutex_lock(tsd_tsdn(tsd), &ctl_mtx);
+	MIB_UNSIGNED(arena_ind, 1);
+	if (arena_ind < narenas_total_get() && (arena =
+	    arena_get(tsd_tsdn(tsd), arena_ind, false)) != NULL) {
+		size_t old_limit, new_limit;
+		if (newp != NULL) {
+			WRITE(new_limit, size_t);
+		}
+		bool err = arena_retain_grow_limit_get_set(tsd, arena,
+		    &old_limit, newp != NULL ? &new_limit : NULL);
+		if (!err) {
+			READ(old_limit, size_t);
+			ret = 0;
+		} else {
+			ret = EFAULT;
+		}
+	} else {
+		ret = EFAULT;
+	}
+label_return:
+	malloc_mutex_unlock(tsd_tsdn(tsd), &ctl_mtx);
+	return ret;
+}
+
 static const ctl_named_node_t *
 arena_i_index(tsdn_t *tsdn, const size_t *mib, size_t miblen, size_t i) {
 	const ctl_named_node_t *ret;

src/extent.c

@@ -1284,13 +1284,14 @@ extent_grow_retained(tsdn_t *tsdn, arena_t *arena,
 	}
 
 	/*
-	 * Increment extent_grow_next if doing so wouldn't exceed the legal
+	 * Increment extent_grow_next if doing so wouldn't exceed the allowed
 	 * range.
 	 */
-	if (arena->extent_grow_next + egn_skip + 1 < NPSIZES) {
+	if (arena->extent_grow_next + egn_skip + 1 <=
+	    arena->retain_grow_limit) {
 		arena->extent_grow_next += egn_skip + 1;
 	} else {
-		arena->extent_grow_next = NPSIZES - 1;
+		arena->extent_grow_next = arena->retain_grow_limit;
 	}
 	/* All opportunities for failure are past. */
 	malloc_mutex_unlock(tsdn, &arena->extent_grow_mtx);

test/unit/mallctl.c

@@ -556,6 +556,54 @@ TEST_BEGIN(test_arena_i_dss) {
 }
 TEST_END
 
+TEST_BEGIN(test_arena_i_retain_grow_limit) {
+	size_t old_limit, new_limit, default_limit;
+	size_t mib[3];
+	size_t miblen;
+
+	bool retain_enabled;
+	size_t sz = sizeof(retain_enabled);
+	assert_d_eq(mallctl("opt.retain", &retain_enabled, &sz, NULL, 0),
+	    0, "Unexpected mallctl() failure");
+	test_skip_if(!retain_enabled);
+
+	sz = sizeof(default_limit);
+	miblen = sizeof(mib)/sizeof(size_t);
+	assert_d_eq(mallctlnametomib("arena.0.retain_grow_limit", mib, &miblen),
+	    0, "Unexpected mallctlnametomib() error");
+
+	assert_d_eq(mallctlbymib(mib, miblen, &default_limit, &sz, NULL, 0), 0,
+	    "Unexpected mallctl() failure");
+	assert_zu_eq(default_limit, sz_pind2sz(EXTENT_GROW_MAX_PIND),
+	    "Unexpected default for retain_grow_limit");
+
+	new_limit = PAGE - 1;
+	assert_d_eq(mallctlbymib(mib, miblen, NULL, NULL, &new_limit,
+	    sizeof(new_limit)), EFAULT, "Unexpected mallctl() success");
+
+	new_limit = PAGE + 1;
+	assert_d_eq(mallctlbymib(mib, miblen, NULL, NULL, &new_limit,
+	    sizeof(new_limit)), 0, "Unexpected mallctl() failure");
+	assert_d_eq(mallctlbymib(mib, miblen, &old_limit, &sz, NULL, 0), 0,
+	    "Unexpected mallctl() failure");
+	assert_zu_eq(old_limit, PAGE,
+	    "Unexpected value for retain_grow_limit");
+
+	/* Expect grow less than psize class 10. */
+	new_limit = sz_pind2sz(10) - 1;
+	assert_d_eq(mallctlbymib(mib, miblen, NULL, NULL, &new_limit,
+	    sizeof(new_limit)), 0, "Unexpected mallctl() failure");
+	assert_d_eq(mallctlbymib(mib, miblen, &old_limit, &sz, NULL, 0), 0,
+	    "Unexpected mallctl() failure");
+	assert_zu_eq(old_limit, sz_pind2sz(9),
+	    "Unexpected value for retain_grow_limit");
+
+	/* Restore to default. */
+	assert_d_eq(mallctlbymib(mib, miblen, NULL, NULL, &default_limit,
+	    sizeof(default_limit)), 0, "Unexpected mallctl() failure");
+}
+TEST_END
+
 TEST_BEGIN(test_arenas_dirty_decay_ms) {
 	ssize_t dirty_decay_ms, orig_dirty_decay_ms, prev_dirty_decay_ms;
 	size_t sz = sizeof(ssize_t);
@@ -727,6 +775,7 @@ main(void) {
 	    test_arena_i_purge,
 	    test_arena_i_decay,
 	    test_arena_i_dss,
+	    test_arena_i_retain_grow_limit,
 	    test_arenas_dirty_decay_ms,
 	    test_arenas_muzzy_decay_ms,
 	    test_arenas_constants,