Switch from opt.lg_tcache_max to opt.tcache_max

Though for convenience, keep parsing lg_tcache_max.

doc/jemalloc.xml.in

@@ -1301,21 +1301,23 @@ malloc_conf = "xmalloc:true";]]></programlisting>
         a certain size.  Thread-specific caching allows many allocations to be
         satisfied without performing any thread synchronization, at the cost of
         increased memory use.  See the <link
-        linkend="opt.lg_tcache_max"><mallctl>opt.lg_tcache_max</mallctl></link>
+        linkend="opt.tcache_max"><mallctl>opt.tcache_max</mallctl></link>
         option for related tuning information.  This option is enabled by
         default.</para></listitem>
       </varlistentry>
 
-      <varlistentry id="opt.lg_tcache_max">
+      <varlistentry id="opt.tcache_max">
         <term>
-          <mallctl>opt.lg_tcache_max</mallctl>
+          <mallctl>opt.tcache_max</mallctl>
           (<type>size_t</type>)
           <literal>r-</literal>
         </term>
-        <listitem><para>Maximum size class (log base 2) to cache in the
+        <listitem><para>Maximum size class to cache in the thread-specific cache
-        thread-specific cache (tcache).  At a minimum, all small size classes
+        (tcache).  At a minimum, all small size classes are cached; and at a
-        are cached; and at a maximum, size classes up to 8 MiB can be cached.
+        maximum, size classes up to 8 MiB can be cached.  The default maximum is
-        The default maximum is 32 KiB (2^15).</para></listitem>
+        32 KiB (2^15).  As a convenience, this may also be set by specifying
+        lg_tcache_max, which will be taken to be the base-2 logarithm of the
+        setting of tcache_max</para></listitem>
       </varlistentry>
 
       <varlistentry id="opt.thp">

include/jemalloc/internal/tcache_externs.h

@@ -2,7 +2,7 @@
 #define JEMALLOC_INTERNAL_TCACHE_EXTERNS_H
 
 extern bool opt_tcache;
-extern ssize_t opt_lg_tcache_max;
+extern size_t opt_tcache_max;
 extern ssize_t	opt_lg_tcache_nslots_mul;
 extern unsigned opt_tcache_nslots_small_min;
 extern unsigned opt_tcache_nslots_small_max;

src/ctl.c

@@ -109,7 +109,7 @@ CTL_PROTO(opt_zero)
 CTL_PROTO(opt_utrace)
 CTL_PROTO(opt_xmalloc)
 CTL_PROTO(opt_tcache)
-CTL_PROTO(opt_lg_tcache_max)
+CTL_PROTO(opt_tcache_max)
 CTL_PROTO(opt_tcache_nslots_small_min)
 CTL_PROTO(opt_tcache_nslots_small_max)
 CTL_PROTO(opt_tcache_nslots_large)
@@ -362,7 +362,7 @@ static const ctl_named_node_t opt_node[] = {
 	{NAME("utrace"),	CTL(opt_utrace)},
 	{NAME("xmalloc"),	CTL(opt_xmalloc)},
 	{NAME("tcache"),	CTL(opt_tcache)},
-	{NAME("lg_tcache_max"),	CTL(opt_lg_tcache_max)},
+	{NAME("tcache_max"),	CTL(opt_tcache_max)},
 	{NAME("tcache_nslots_small_min"),
 		CTL(opt_tcache_nslots_small_min)},
 	{NAME("tcache_nslots_small_max"),
@@ -1837,7 +1837,7 @@ CTL_RO_NL_CGEN(config_fill, opt_zero, opt_zero, bool)
 CTL_RO_NL_CGEN(config_utrace, opt_utrace, opt_utrace, bool)
 CTL_RO_NL_CGEN(config_xmalloc, opt_xmalloc, opt_xmalloc, bool)
 CTL_RO_NL_GEN(opt_tcache, opt_tcache, bool)
-CTL_RO_NL_GEN(opt_lg_tcache_max, opt_lg_tcache_max, ssize_t)
+CTL_RO_NL_GEN(opt_tcache_max, opt_tcache_max, size_t)
 CTL_RO_NL_GEN(opt_tcache_nslots_small_min, opt_tcache_nslots_small_min,
     unsigned)
 CTL_RO_NL_GEN(opt_tcache_nslots_small_max, opt_tcache_nslots_small_max,

src/jemalloc.c

@@ -1170,15 +1170,18 @@ malloc_conf_init_helper(sc_data_t *sc_data, unsigned bin_shard_sizes[SC_NBINS],
 #define CONF_DONT_CHECK_MAX(um, max)	false
 #define CONF_CHECK_MAX(um, max)	((um) > (max))
 
+#define CONF_VALUE_READ(max_t, result)					\
+	      char *end;						\
+	      set_errno(0);						\
+	      result = (max_t)malloc_strtoumax(v, &end, 0);
+#define CONF_VALUE_READ_FAIL()						\
+	      (get_errno() != 0 || (uintptr_t)end - (uintptr_t)v != vlen)
+
 #define CONF_HANDLE_T(t, max_t, o, n, min, max, check_min, check_max, clip) \
 			if (CONF_MATCH(n)) {				\
 				max_t mv;				\
-				char *end;				\
+				CONF_VALUE_READ(max_t, mv)		\
-									\
+				if (CONF_VALUE_READ_FAIL()) {		\
-				set_errno(0);				\
-				mv = (max_t)malloc_strtoumax(v, &end, 0); \
-				if (get_errno() != 0 || (uintptr_t)end -\
-				    (uintptr_t)v != vlen) {		\
 					CONF_ERROR("Invalid conf value",\
 					    k, klen, v, vlen);		\
 				} else if (clip) {			\
@@ -1379,8 +1382,24 @@ malloc_conf_init_helper(sc_data_t *sc_data, unsigned bin_shard_sizes[SC_NBINS],
 				CONF_HANDLE_BOOL(opt_xmalloc, "xmalloc")
 			}
 			CONF_HANDLE_BOOL(opt_tcache, "tcache")
-			CONF_HANDLE_SSIZE_T(opt_lg_tcache_max, "lg_tcache_max",
+			CONF_HANDLE_SIZE_T(opt_tcache_max, "tcache_max",
-			    -1, (sizeof(size_t) << 3) - 1)
+			    0, TCACHE_MAXCLASS_LIMIT, CONF_DONT_CHECK_MIN,
+			    CONF_CHECK_MAX, /* clip */ true)
+			if (CONF_MATCH("lg_tcache_max")) {
+				size_t m;
+				CONF_VALUE_READ(size_t, m)
+				if (CONF_VALUE_READ_FAIL()) {
+					CONF_ERROR("Invalid conf value",
+					    k, klen, v, vlen);
+				} else {
+					/* clip if necessary */
+					if (m > TCACHE_LG_MAXCLASS_LIMIT) {
+						m = TCACHE_LG_MAXCLASS_LIMIT;
+					}
+					opt_tcache_max = (size_t)1 << m;
+				}
+				CONF_CONTINUE;
+			}
 			/*
 			 * Anyone trying to set a value outside -16 to 16 is
 			 * deeply confused.

src/tcache.c

@@ -11,11 +11,8 @@
 
 bool opt_tcache = true;
 
-/*
+/* tcache_maxclass is set to 32KB by default.  */
- * (1U << opt_lg_tcache_max) is used to compute tcache_maxclass.  This choice
+size_t opt_tcache_max = ((size_t)1) << 15;
- * (32kb by default) works well as a default in practice.
- */
-ssize_t opt_lg_tcache_max = 15;
 
 /* Reasonable defaults for min and max values. */
 unsigned opt_tcache_nslots_small_min = 20;
@@ -935,14 +932,11 @@ tcache_ncached_max_compute(szind_t szind) {
 
 bool
 tcache_boot(tsdn_t *tsdn, base_t *base) {
-	/* If necessary, clamp opt_lg_tcache_max. */
+	tcache_maxclass = sz_s2u(opt_tcache_max);
-	tcache_maxclass = opt_lg_tcache_max < 0 ? 0 :
-	    ZU(1) << opt_lg_tcache_max;
 	if (tcache_maxclass < SC_SMALL_MAXCLASS) {
 		tcache_maxclass = SC_SMALL_MAXCLASS;
-	} else if (tcache_maxclass > TCACHE_MAXCLASS_LIMIT) {
-		tcache_maxclass = TCACHE_MAXCLASS_LIMIT;
 	}
+	assert(tcache_maxclass <= TCACHE_MAXCLASS_LIMIT);
 	nhbins = sz_size2index(tcache_maxclass) + 1;
 
 	if (malloc_mutex_init(&tcaches_mtx, "tcaches", WITNESS_RANK_TCACHES,

test/unit/mallctl.c

@@ -179,7 +179,7 @@ TEST_BEGIN(test_mallctl_opt) {
 	TEST_MALLCTL_OPT(bool, xmalloc, xmalloc);
 	TEST_MALLCTL_OPT(bool, tcache, always);
 	TEST_MALLCTL_OPT(size_t, lg_extent_max_active_fit, always);
-	TEST_MALLCTL_OPT(size_t, lg_tcache_max, always);
+	TEST_MALLCTL_OPT(size_t, tcache_max, always);
 	TEST_MALLCTL_OPT(const char *, thp, always);
 	TEST_MALLCTL_OPT(const char *, zero_realloc, always);
 	TEST_MALLCTL_OPT(bool, prof, prof);

test/unit/stats.c

@@ -393,7 +393,7 @@ test_tcache_bytes_for_usize(size_t usize) {
 TEST_BEGIN(test_stats_tcache_bytes_small) {
 	test_skip_if(!config_stats);
 	test_skip_if(!opt_tcache);
-	test_skip_if((ZU(1) << opt_lg_tcache_max) < SC_SMALL_MAXCLASS);
+	test_skip_if(opt_tcache_max < SC_SMALL_MAXCLASS);
 
 	test_tcache_bytes_for_usize(SC_SMALL_MAXCLASS);
 }
@@ -402,7 +402,7 @@ TEST_END
 TEST_BEGIN(test_stats_tcache_bytes_large) {
 	test_skip_if(!config_stats);
 	test_skip_if(!opt_tcache);
-	test_skip_if((ZU(1) << opt_lg_tcache_max) < SC_LARGE_MINCLASS);
+	test_skip_if(opt_tcache_max < SC_LARGE_MINCLASS);
 
 	test_tcache_bytes_for_usize(SC_LARGE_MINCLASS);
 }