net: revert "Update RFS target at poll for tcp/udp"

On multi-threaded processes, one common architecture is to have
one (or a small number of) threads polling sockets, and a
considerably larger pool of threads reading form and writing to the
sockets. When we set RPS core on tcp_poll() or udp_poll() we essentially
steer all packets of all the polled FDs to one (or small number of)
cores, creaing a bottleneck and/or RPS misprediction.

Another common architecture is to shard FDs among threads pinned
to cores. In such a setting, setting RPS core in tcp_poll() and
udp_poll() is redundant because the RFS core is correctly
set in recvmsg and sendmsg.

Thus, revert the following commit:
c3f1dbaf6e28 ("net: Update RFS target at poll for tcp/udp").

Signed-off-by: Soheil Hassas Yeganeh <soheil@google.com>
Signed-off-by: Willem de Bruijn <willemb@google.com>
Signed-off-by: Eric Dumazet <edumazet@google.com>
Signed-off-by: Neal Cardwell <ncardwell@google.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

diff --git a/net/ipv4/tcp.c b/net/ipv4/tcp.c
index 7ac583a2b9fe09cebbd17baceca2019e06ea9d3e..f68cb33d50d1d43a4cf6234e7e10e2a689974eb5 100644 (file)
--- a/net/ipv4/tcp.c
+++ b/net/ipv4/tcp.c
@@ -498,8 +498,6 @@ unsigned int tcp_poll(struct file *file, struct socket *sock, poll_table *wait)
        const struct tcp_sock *tp = tcp_sk(sk);
        int state;
 
-       sock_rps_record_flow(sk);
-
        sock_poll_wait(file, sk_sleep(sk), wait);
 
        state = inet_sk_state_load(sk);

diff --git a/net/ipv4/udp.c b/net/ipv4/udp.c
index e9c0d1e1772e6c59827df48c9fe8017d6e3b515d..db72619e07e423aa8171b0e2200850979c0e7d1f 100644 (file)
--- a/net/ipv4/udp.c
+++ b/net/ipv4/udp.c
@@ -2490,8 +2490,6 @@ unsigned int udp_poll(struct file *file, struct socket *sock, poll_table *wait)
        if (!skb_queue_empty(&udp_sk(sk)->reader_queue))
                mask |= POLLIN | POLLRDNORM;
 
-       sock_rps_record_flow(sk);
-
        /* Check for false positives due to checksum errors */
        if ((mask & POLLRDNORM) && !(file->f_flags & O_NONBLOCK) &&
            !(sk->sk_shutdown & RCV_SHUTDOWN) && first_packet_length(sk) == -1)