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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>
This commit is contained in:
Andy Grover 2010-03-11 13:50:04 +00:00 committed by David S. Miller
parent 550a8002e4
commit b98ba52f96
3 changed files with 11 additions and 2 deletions
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7
net/rds/af_rds.c
View File

@ -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;
}

2
net/rds/rds.h
View File

@ -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;

4
net/rds/send.c
View File

@ -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)) {