Implement per-CPU arena.

The new feature, opt.percpu_arena, determines thread-arena association
dynamically based CPU id. Three modes are supported: "percpu", "phycpu"
and disabled.

"percpu" uses the current core id (with help from sched_getcpu())
directly as the arena index, while "phycpu" will assign threads on the
same physical CPU to the same arena. In other words, "percpu" means # of
arenas == # of CPUs, while "phycpu" has # of arenas == 1/2 * (# of
CPUs). Note that no runtime check on whether hyper threading is enabled
is added yet.

When enabled, threads will be migrated between arenas when a CPU change
is detected. In the current design, to reduce overhead from reading CPU
id, each arena tracks the thread accessed most recently. When a new
thread comes in, we will read CPU id and update arena if necessary.

1 files changed, 17 insertions, 8 deletions

diff --git a/test/integration/thread_arena.c b/test/integration/thread_arena.c
index 9991a42..1e5ec05 100644
--- a/test/integration/thread_arena.c
+++ b/test/integration/thread_arena.c
@@ -37,10 +37,16 @@ thd_start(void *arg) {
 	return NULL;
 }
 
+static void
+mallctl_failure(int err) {
+	char buf[BUFERROR_BUF];
+
+	buferror(err, buf, sizeof(buf));
+	test_fail("Error in mallctl(): %s", buf);
+}
+
 TEST_BEGIN(test_thread_arena) {
 	void *p;
-	unsigned arena_ind;
-	size_t size;
 	int err;
 	thd_t thds[NTHREADS];
 	unsigned i;
@@ -48,13 +54,15 @@ TEST_BEGIN(test_thread_arena) {
 	p = malloc(1);
 	assert_ptr_not_null(p, "Error in malloc()");
 
-	size = sizeof(arena_ind);
-	if ((err = mallctl("thread.arena", (void *)&arena_ind, &size, NULL,
-	    0))) {
-		char buf[BUFERROR_BUF];
+	unsigned arena_ind, old_arena_ind;
+	size_t sz = sizeof(unsigned);
+	assert_d_eq(mallctl("arenas.create", (void *)&arena_ind, &sz, NULL, 0),
+	    0, "Arena creation failure");
 
-		buferror(err, buf, sizeof(buf));
-		test_fail("Error in mallctl(): %s", buf);
+	size_t size = sizeof(arena_ind);
+	if ((err = mallctl("thread.arena", (void *)&old_arena_ind, &size,
+	    (void *)&arena_ind, sizeof(arena_ind))) != 0) {
+		mallctl_failure(err);
 	}
 
 	for (i = 0; i < NTHREADS; i++) {
@@ -67,6 +75,7 @@ TEST_BEGIN(test_thread_arena) {
 		thd_join(thds[i], (void *)&join_ret);
 		assert_zd_eq(join_ret, 0, "Unexpected thread join error");
 	}
+	free(p);
 }
 TEST_END