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Subject[PATCH 001 of 11] knfsd: move tempsock aging to a timer

From: Greg Banks <gnb@melbourne.sgi.com>

knfsd: Move the aging of RPC/TCP connection sockets from the main
svc_recv() loop to a timer which uses a mark-and-sweep algorithm
every 6 minutes. This reduces the amount of work that needs to be
done in the main RPC loop and the length of time we need to hold
the (effectively global) svc_serv->sv_lock.


Signed-off-by: Greg Banks <gnb@melbourne.sgi.com>
Signed-off-by: Neil Brown <neilb@suse.de>

### Diffstat output
./include/linux/sunrpc/svc.h | 1
./include/linux/sunrpc/svcsock.h | 2
./net/sunrpc/svc.c | 3 +
./net/sunrpc/svcsock.c | 96 ++++++++++++++++++++++++++++-----------
4 files changed, 76 insertions(+), 26 deletions(-)
diff .prev/include/linux/sunrpc/svc.h ./include/linux/sunrpc/svc.h
--- .prev/include/linux/sunrpc/svc.h 2006-07-28 11:54:16.000000000 +1000
+++ ./include/linux/sunrpc/svc.h 2006-07-31 09:56:44.000000000 +1000
@@ -40,6 +40,7 @@ struct svc_serv {
struct list_head sv_permsocks; /* all permanent sockets */
struct list_head sv_tempsocks; /* all temporary sockets */
int sv_tmpcnt; /* count of temporary sockets */
+ struct timer_list sv_temptimer; /* timer for aging temporary sockets */

char * sv_name; /* service name */

diff .prev/include/linux/sunrpc/svcsock.h ./include/linux/sunrpc/svcsock.h
--- .prev/include/linux/sunrpc/svcsock.h 2006-07-28 11:54:40.000000000 +1000
+++ ./include/linux/sunrpc/svcsock.h 2006-07-31 09:56:44.000000000 +1000
@@ -31,6 +31,8 @@ struct svc_sock {
#define SK_DEAD 6 /* socket closed */
#define SK_CHNGBUF 7 /* need to change snd/rcv buffer sizes */
#define SK_DEFERRED 8 /* request on sk_deferred */
+#define SK_OLD 9 /* used for temp socket aging mark+sweep */
+#define SK_DETACHED 10 /* detached from tempsocks list */

int sk_reserved; /* space on outq that is reserved */

diff .prev/net/sunrpc/svc.c ./net/sunrpc/svc.c
--- .prev/net/sunrpc/svc.c 2006-07-28 11:53:47.000000000 +1000
+++ ./net/sunrpc/svc.c 2006-07-31 09:56:44.000000000 +1000
@@ -59,6 +59,7 @@ svc_create(struct svc_program *prog, uns
INIT_LIST_HEAD(&serv->sv_sockets);
INIT_LIST_HEAD(&serv->sv_tempsocks);
INIT_LIST_HEAD(&serv->sv_permsocks);
+ init_timer(&serv->sv_temptimer);
spin_lock_init(&serv->sv_lock);

/* Remove any stale portmap registrations */
@@ -87,6 +88,8 @@ svc_destroy(struct svc_serv *serv)
} else
printk("svc_destroy: no threads for serv=%p!\n", serv);

+ del_timer_sync(&serv->sv_temptimer);
+
while (!list_empty(&serv->sv_tempsocks)) {
svsk = list_entry(serv->sv_tempsocks.next,
struct svc_sock,
diff .prev/net/sunrpc/svcsock.c ./net/sunrpc/svcsock.c
--- .prev/net/sunrpc/svcsock.c 2006-07-28 11:55:15.000000000 +1000
+++ ./net/sunrpc/svcsock.c 2006-07-31 09:56:44.000000000 +1000
@@ -74,6 +74,13 @@ static struct svc_deferred_req *svc_defe
static int svc_deferred_recv(struct svc_rqst *rqstp);
static struct cache_deferred_req *svc_defer(struct cache_req *req);

+/* apparently the "standard" is that clients close
+ * idle connections after 5 minutes, servers after
+ * 6 minutes
+ * http://www.connectathon.org/talks96/nfstcp.pdf
+ */
+static int svc_conn_age_period = 6*60;
+
/*
* Queue up an idle server thread. Must have serv->sv_lock held.
* Note: this is really a stack rather than a queue, so that we only
@@ -1230,24 +1237,7 @@ svc_recv(struct svc_rqst *rqstp, long ti
return -EINTR;

spin_lock_bh(&serv->sv_lock);
- if (!list_empty(&serv->sv_tempsocks)) {
- svsk = list_entry(serv->sv_tempsocks.next,
- struct svc_sock, sk_list);
- /* apparently the "standard" is that clients close
- * idle connections after 5 minutes, servers after
- * 6 minutes
- * http://www.connectathon.org/talks96/nfstcp.pdf
- */
- if (get_seconds() - svsk->sk_lastrecv < 6*60
- || test_bit(SK_BUSY, &svsk->sk_flags))
- svsk = NULL;
- }
- if (svsk) {
- set_bit(SK_BUSY, &svsk->sk_flags);
- set_bit(SK_CLOSE, &svsk->sk_flags);
- rqstp->rq_sock = svsk;
- svsk->sk_inuse++;
- } else if ((svsk = svc_sock_dequeue(serv)) != NULL) {
+ if ((svsk = svc_sock_dequeue(serv)) != NULL) {
rqstp->rq_sock = svsk;
svsk->sk_inuse++;
rqstp->rq_reserved = serv->sv_bufsz;
@@ -1292,13 +1282,7 @@ svc_recv(struct svc_rqst *rqstp, long ti
return -EAGAIN;
}
svsk->sk_lastrecv = get_seconds();
- if (test_bit(SK_TEMP, &svsk->sk_flags)) {
- /* push active sockets to end of list */
- spin_lock_bh(&serv->sv_lock);
- if (!list_empty(&svsk->sk_list))
- list_move_tail(&svsk->sk_list, &serv->sv_tempsocks);
- spin_unlock_bh(&serv->sv_lock);
- }
+ clear_bit(SK_OLD, &svsk->sk_flags);

rqstp->rq_secure = ntohs(rqstp->rq_addr.sin_port) < 1024;
rqstp->rq_chandle.defer = svc_defer;
@@ -1358,6 +1342,58 @@ svc_send(struct svc_rqst *rqstp)
}

/*
+ * Timer function to close old temporary sockets, using
+ * a mark-and-sweep algorithm.
+ */
+static void
+svc_age_temp_sockets(unsigned long closure)
+{
+ struct svc_serv *serv = (struct svc_serv *)closure;
+ struct svc_sock *svsk;
+ struct list_head *le, *next;
+ LIST_HEAD(to_be_aged);
+
+ dprintk("svc_age_temp_sockets\n");
+
+ if (!spin_trylock_bh(&serv->sv_lock)) {
+ /* busy, try again 1 sec later */
+ dprintk("svc_age_temp_sockets: busy\n");
+ mod_timer(&serv->sv_temptimer, jiffies + HZ);
+ return;
+ }
+
+ list_for_each_safe(le, next, &serv->sv_tempsocks) {
+ svsk = list_entry(le, struct svc_sock, sk_list);
+
+ if (!test_and_set_bit(SK_OLD, &svsk->sk_flags))
+ continue;
+ if (svsk->sk_inuse || test_bit(SK_BUSY, &svsk->sk_flags))
+ continue;
+ svsk->sk_inuse++;
+ list_move(le, &to_be_aged);
+ set_bit(SK_CLOSE, &svsk->sk_flags);
+ set_bit(SK_DETACHED, &svsk->sk_flags);
+ }
+ spin_unlock_bh(&serv->sv_lock);
+
+ while (!list_empty(&to_be_aged)) {
+ le = to_be_aged.next;
+ /* fiddling the sk_list node is safe 'cos we're SK_DETACHED */
+ list_del_init(le);
+ svsk = list_entry(le, struct svc_sock, sk_list);
+
+ dprintk("queuing svsk %p for closing, %lu seconds old\n",
+ svsk, get_seconds() - svsk->sk_lastrecv);
+
+ /* a thread will dequeue and close it soon */
+ svc_sock_enqueue(svsk);
+ svc_sock_put(svsk);
+ }
+
+ mod_timer(&serv->sv_temptimer, jiffies + svc_conn_age_period * HZ);
+}
+
+/*
* Initialize socket for RPC use and create svc_sock struct
* XXX: May want to setsockopt SO_SNDBUF and SO_RCVBUF.
*/
@@ -1410,6 +1446,13 @@ svc_setup_socket(struct svc_serv *serv,
set_bit(SK_TEMP, &svsk->sk_flags);
list_add(&svsk->sk_list, &serv->sv_tempsocks);
serv->sv_tmpcnt++;
+ if (serv->sv_temptimer.function == NULL) {
+ /* setup timer to age temp sockets */
+ serv->sv_temptimer.function = svc_age_temp_sockets;
+ serv->sv_temptimer.data = (unsigned long)serv;
+ serv->sv_temptimer.expires = jiffies + svc_conn_age_period * HZ;
+ add_timer(&serv->sv_temptimer);
+ }
} else {
clear_bit(SK_TEMP, &svsk->sk_flags);
list_add(&svsk->sk_list, &serv->sv_permsocks);
@@ -1525,7 +1568,8 @@ svc_delete_socket(struct svc_sock *svsk)

spin_lock_bh(&serv->sv_lock);

- list_del_init(&svsk->sk_list);
+ if (!test_and_set_bit(SK_DETACHED, &svsk->sk_flags))
+ list_del_init(&svsk->sk_list);
list_del_init(&svsk->sk_ready);
if (!test_and_set_bit(SK_DEAD, &svsk->sk_flags))
if (test_bit(SK_TEMP, &svsk->sk_flags))
-
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