From: Willy Tarreau <w@1wt.eu>
Date: Wed, 3 Mar 2021 17:12:11 +0000 (+0100)
Subject: MINOR: server: don't read curr_used_conns multiple times
X-Git-Tag: v2.4-dev11~13
X-Git-Url: http://git.haproxy.org/?a=commitdiff_plain;h=cc2672f48ba20b68e90144775c0c70839f87ca50;p=haproxy-2.5.git

MINOR: server: don't read curr_used_conns multiple times

This one is added atomically and we reread it just after this, causing
a second memory load that is visible in the perf profile.
---

diff --git a/include/haproxy/server.h b/include/haproxy/server.h
index 2c5d979..4892abd 100644
--- a/include/haproxy/server.h
+++ b/include/haproxy/server.h
@@ -247,16 +247,18 @@ static inline enum srv_initaddr srv_get_next_initaddr(unsigned int *list)
 
 static inline void srv_use_conn(struct server *srv, struct connection *conn)
 {
-	_HA_ATOMIC_ADD(&srv->curr_used_conns, 1);
+	unsigned int curr;
+
+	curr = _HA_ATOMIC_ADD(&srv->curr_used_conns, 1);
 
 	/* It's ok not to do that atomically, we don't need an
 	 * exact max.
 	 */
-	if (srv->max_used_conns < srv->curr_used_conns)
-		srv->max_used_conns = srv->curr_used_conns;
+	if (srv->max_used_conns < curr)
+		srv->max_used_conns = curr;
 
-	if (srv->est_need_conns < srv->curr_used_conns)
-		srv->est_need_conns = srv->curr_used_conns;
+	if (srv->est_need_conns < curr)
+		srv->est_need_conns = curr;
 }
 
 static inline void conn_delete_from_tree(struct ebmb_node *node)