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authorEric Dumazet <edumazet@google.com>2016-12-03 11:14:52 -0800
committerDavid S. Miller <davem@davemloft.net>2016-12-05 13:32:22 -0500
commitb223feb9de2a65c533ff95c08e834fa732906ea5 (patch)
tree0327e31d3fe77301791b56fd3a4082cb3229737e /net
parent408f0a6c21e124cc4f6c7aa370b38aa47e55428d (diff)
tcp: tsq: add shortcut in tcp_tasklet_func()
Under high stress, I've seen tcp_tasklet_func() consuming ~700 usec, handling ~150 tcp sockets. By setting TCP_TSQ_DEFERRED in tcp_wfree(), we give a chance for other cpus/threads entering tcp_write_xmit() to grab it, allowing tcp_tasklet_func() to skip sockets that already did an xmit cycle. In the future, we might give to ACK processing an increased budget to reduce even more tcp_tasklet_func() amount of work. Signed-off-by: Eric Dumazet <edumazet@google.com> Signed-off-by: David S. Miller <davem@davemloft.net>
Diffstat (limited to 'net')
-rw-r--r--net/ipv4/tcp_output.c22
1 files changed, 12 insertions, 10 deletions
diff --git a/net/ipv4/tcp_output.c b/net/ipv4/tcp_output.c
index 4adaf8e1bb63..fa23b688a6f3 100644
--- a/net/ipv4/tcp_output.c
+++ b/net/ipv4/tcp_output.c
@@ -767,19 +767,19 @@ static void tcp_tasklet_func(unsigned long data)
list_for_each_safe(q, n, &list) {
tp = list_entry(q, struct tcp_sock, tsq_node);
list_del(&tp->tsq_node);
+ clear_bit(TSQ_QUEUED, &tp->tsq_flags);
sk = (struct sock *)tp;
- bh_lock_sock(sk);
-
- if (!sock_owned_by_user(sk)) {
- tcp_tsq_handler(sk);
- } else {
- /* defer the work to tcp_release_cb() */
- set_bit(TCP_TSQ_DEFERRED, &tp->tsq_flags);
+ if (!sk->sk_lock.owned &&
+ test_bit(TCP_TSQ_DEFERRED, &tp->tsq_flags)) {
+ bh_lock_sock(sk);
+ if (!sock_owned_by_user(sk)) {
+ clear_bit(TCP_TSQ_DEFERRED, &tp->tsq_flags);
+ tcp_tsq_handler(sk);
+ }
+ bh_unlock_sock(sk);
}
- bh_unlock_sock(sk);
- clear_bit(TSQ_QUEUED, &tp->tsq_flags);
sk_free(sk);
}
}
@@ -884,7 +884,7 @@ void tcp_wfree(struct sk_buff *skb)
if (!(oval & TSQF_THROTTLED) || (oval & TSQF_QUEUED))
goto out;
- nval = (oval & ~TSQF_THROTTLED) | TSQF_QUEUED;
+ nval = (oval & ~TSQF_THROTTLED) | TSQF_QUEUED | TCPF_TSQ_DEFERRED;
nval = cmpxchg(&tp->tsq_flags, oval, nval);
if (nval != oval)
continue;
@@ -2229,6 +2229,8 @@ static bool tcp_write_xmit(struct sock *sk, unsigned int mss_now, int nonagle,
unlikely(tso_fragment(sk, skb, limit, mss_now, gfp)))
break;
+ if (test_bit(TCP_TSQ_DEFERRED, &tp->tsq_flags))
+ clear_bit(TCP_TSQ_DEFERRED, &tp->tsq_flags);
if (tcp_small_queue_check(sk, skb, 0))
break;