OPTIM: server: switch the actconn list to an mt-list
The remaining contention on the server lock solely comes from
sess_change_server() which takes the lock to add and remove a
stream from the server's actconn list. This is both expensive
and pointless since we have mt-lists, and this list is only
used by the CLI's "shutdown server sessions" command!
Let's migrate to an mt-list and remove the need for this costly
lock. By doing so, the request rate increased by ~1.8%.
(cherry picked from commit 751153e0f119bec90455cda95166f1b29d8b0326)
[wt: the contention is extreme on high threads counts, thus this
actconn series is backported; ctx adjustments]
Signed-off-by: Willy Tarreau <w@1wt.eu>
diff --git a/src/hlua.c b/src/hlua.c
index 550b592..8dd2f31 100644
--- a/src/hlua.c
+++ b/src/hlua.c
@@ -8750,7 +8750,7 @@
socket_tcp.next = NULL;
socket_tcp.proxy = &socket_proxy;
socket_tcp.obj_type = OBJ_TYPE_SERVER;
- LIST_INIT(&socket_tcp.actconns);
+ MT_LIST_INIT(&socket_tcp.actconns);
socket_tcp.pendconns = EB_ROOT;
socket_tcp.idle_conns = NULL;
socket_tcp.safe_conns = NULL;
@@ -8795,7 +8795,7 @@
socket_ssl.next = NULL;
socket_ssl.proxy = &socket_proxy;
socket_ssl.obj_type = OBJ_TYPE_SERVER;
- LIST_INIT(&socket_ssl.actconns);
+ MT_LIST_INIT(&socket_ssl.actconns);
socket_ssl.pendconns = EB_ROOT;
socket_ssl.idle_conns = NULL;
socket_ssl.safe_conns = NULL;
diff --git a/src/queue.c b/src/queue.c
index 19b99a5..ea99761 100644
--- a/src/queue.c
+++ b/src/queue.c
@@ -328,7 +328,7 @@
__ha_barrier_atomic_store();
if (px->lbprm.server_take_conn)
px->lbprm.server_take_conn(srv);
- __stream_add_srv_conn(p->strm, srv);
+ stream_add_srv_conn(p->strm, srv);
task_wakeup(p->strm->task, TASK_WOKEN_RES);
diff --git a/src/server.c b/src/server.c
index d741f16..13eb676 100644
--- a/src/server.c
+++ b/src/server.c
@@ -863,9 +863,10 @@
*/
void srv_shutdown_streams(struct server *srv, int why)
{
- struct stream *stream, *stream_bck;
+ struct stream *stream;
+ struct mt_list *elt1, elt2;
- list_for_each_entry_safe(stream, stream_bck, &srv->actconns, by_srv)
+ mt_list_for_each_entry_safe(stream, &srv->actconns, by_srv, elt1, elt2)
if (stream->srv_conn == srv)
stream_shutdown(stream, why);
}
@@ -1724,7 +1725,7 @@
srv->obj_type = OBJ_TYPE_SERVER;
srv->proxy = proxy;
- LIST_INIT(&srv->actconns);
+ MT_LIST_INIT(&srv->actconns);
srv->pendconns = EB_ROOT;
srv->next_state = SRV_ST_RUNNING; /* early server setup */
diff --git a/src/stream.c b/src/stream.c
index a2feea1..7b58e2a 100644
--- a/src/stream.c
+++ b/src/stream.c
@@ -2496,17 +2496,19 @@
*/
void sess_change_server(struct stream *sess, struct server *newsrv)
{
- if (sess->srv_conn == newsrv)
+ struct server *oldsrv = sess->srv_conn;
+
+ if (oldsrv == newsrv)
return;
- if (sess->srv_conn) {
- _HA_ATOMIC_SUB(&sess->srv_conn->served, 1);
- _HA_ATOMIC_SUB(&sess->srv_conn->proxy->served, 1);
+ if (oldsrv) {
+ _HA_ATOMIC_SUB(&oldsrv->served, 1);
+ _HA_ATOMIC_SUB(&oldsrv->proxy->served, 1);
__ha_barrier_atomic_store();
- if (sess->srv_conn->proxy->lbprm.server_drop_conn) {
- HA_SPIN_LOCK(SERVER_LOCK, &sess->srv_conn->lock);
- sess->srv_conn->proxy->lbprm.server_drop_conn(sess->srv_conn);
- HA_SPIN_UNLOCK(SERVER_LOCK, &sess->srv_conn->lock);
+ if (oldsrv->proxy->lbprm.server_drop_conn) {
+ HA_SPIN_LOCK(SERVER_LOCK, &oldsrv->lock);
+ oldsrv->proxy->lbprm.server_drop_conn(oldsrv);
+ HA_SPIN_UNLOCK(SERVER_LOCK, &oldsrv->lock);
}
stream_del_srv_conn(sess);
}