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authorAndy Grover <andy.grover@oracle.com>2010-03-11 13:50:04 +0000
committerDavid S. Miller <davem@davemloft.net>2010-03-16 21:16:59 -0700
commitb98ba52f96e7cdb4dbe2b06bced83d95d94c9d02 (patch)
tree72e22772c6326ff554bd030bda35abcb1526249e
parent550a8002e4340eaf3bc333e33b59427e9c20272d (diff)
downloadop-kernel-dev-b98ba52f96e7cdb4dbe2b06bced83d95d94c9d02.zip
op-kernel-dev-b98ba52f96e7cdb4dbe2b06bced83d95d94c9d02.tar.gz
RDS: only put sockets that have seen congestion on the poll_waitq
rds_poll_waitq's listeners will be awoken if we receive a congestion notification. Bad performance may result because *all* polled sockets contend for this single lock. However, it should not be necessary to wake pollers when a congestion update arrives if they have never experienced congestion, and not putting these on the waitq will hopefully greatly reduce contention. Signed-off-by: Andy Grover <andy.grover@oracle.com> Signed-off-by: David S. Miller <davem@davemloft.net>
-rw-r--r--net/rds/af_rds.c7
-rw-r--r--net/rds/rds.h2
-rw-r--r--net/rds/send.c4
3 files changed, 11 insertions, 2 deletions
diff --git a/net/rds/af_rds.c b/net/rds/af_rds.c
index 853c52b..937ecda 100644
--- a/net/rds/af_rds.c
+++ b/net/rds/af_rds.c
@@ -159,7 +159,8 @@ static unsigned int rds_poll(struct file *file, struct socket *sock,
poll_wait(file, sk->sk_sleep, wait);
- poll_wait(file, &rds_poll_waitq, wait);
+ if (rs->rs_seen_congestion)
+ poll_wait(file, &rds_poll_waitq, wait);
read_lock_irqsave(&rs->rs_recv_lock, flags);
if (!rs->rs_cong_monitor) {
@@ -181,6 +182,10 @@ static unsigned int rds_poll(struct file *file, struct socket *sock,
mask |= (POLLOUT | POLLWRNORM);
read_unlock_irqrestore(&rs->rs_recv_lock, flags);
+ /* clear state any time we wake a seen-congested socket */
+ if (mask)
+ rs->rs_seen_congestion = 0;
+
return mask;
}
diff --git a/net/rds/rds.h b/net/rds/rds.h
index 85d6f89..4bec6e2 100644
--- a/net/rds/rds.h
+++ b/net/rds/rds.h
@@ -388,6 +388,8 @@ struct rds_sock {
/* flag indicating we were congested or not */
int rs_congested;
+ /* seen congestion (ENOBUFS) when sending? */
+ int rs_seen_congestion;
/* rs_lock protects all these adjacent members before the newline */
spinlock_t rs_lock;
diff --git a/net/rds/send.c b/net/rds/send.c
index 192a480..51e2def 100644
--- a/net/rds/send.c
+++ b/net/rds/send.c
@@ -894,8 +894,10 @@ int rds_sendmsg(struct kiocb *iocb, struct socket *sock, struct msghdr *msg,
queue_delayed_work(rds_wq, &conn->c_conn_w, 0);
ret = rds_cong_wait(conn->c_fcong, dport, nonblock, rs);
- if (ret)
+ if (ret) {
+ rs->rs_seen_congestion = 1;
goto out;
+ }
while (!rds_send_queue_rm(rs, conn, rm, rs->rs_bound_port,
dport, &queued)) {
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