Convert arena->prof_accumbytes synchronization to atomics.

src/arena.c

@@ -1148,19 +1148,7 @@ arena_prof_promote(tsdn_t *tsdn, extent_t *extent, const void *ptr,
 
 	extent_usize_set(extent, usize);
 
-	/*
-	 * Cancel out as much of the excessive prof_accumbytes increase as
-	 * possible without underflowing.  Interval-triggered dumps occur
-	 * slightly more often than intended as a result of incomplete
-	 * canceling.
-	 */
-	malloc_mutex_lock(tsdn, &arena->lock);
-	if (arena->prof_accumbytes >= LARGE_MINCLASS - usize) {
-		arena->prof_accumbytes -= LARGE_MINCLASS - usize;
-	} else {
-		arena->prof_accumbytes = 0;
-	}
-	malloc_mutex_unlock(tsdn, &arena->lock);
+	prof_accum_cancel(tsdn, &arena->prof_accum, usize);
 
 	assert(isalloc(tsdn, extent, ptr) == usize);
 }
@@ -1574,7 +1562,9 @@ arena_new(tsdn_t *tsdn, unsigned ind, extent_hooks_t *extent_hooks) {
 	}
 
 	if (config_prof) {
-		arena->prof_accumbytes = 0;
+		if (prof_accum_init(tsdn, &arena->prof_accum)) {
+			goto label_error;
+		}
 	}
 
 	if (config_cache_oblivious) {

src/prof.c

@@ -1753,6 +1753,20 @@ prof_fdump(void) {
 	prof_dump(tsd, false, filename, opt_prof_leak);
 }
 
+bool
+prof_accum_init(tsdn_t *tsdn, prof_accum_t *prof_accum) {
+	cassert(config_prof);
+
+#ifndef JEMALLOC_ATOMIC_U64
+	if (malloc_mutex_init(&prof_accum->mtx, "prof_accum",
+	    WITNESS_RANK_PROF_ACCUM)) {
+		return true;
+	}
+#endif
+	prof_accum->accumbytes = 0;
+	return false;
+}
+
 void
 prof_idump(tsdn_t *tsdn) {
 	tsd_t *tsd;

src/tcache.c

@@ -200,7 +200,7 @@ tcache_bin_flush_large(tsd_t *tsd, tcache_bin_t *tbin, szind_t binind,
 		}
 		if ((config_prof || config_stats) && locked_arena == arena) {
 			if (config_prof) {
-				idump = arena_prof_accum_locked(arena,
+				idump = arena_prof_accum(tsd_tsdn(tsd), arena,
 				    tcache->prof_accumbytes);
 				tcache->prof_accumbytes = 0;
 			}