Re: [PATCH] sctp: add support for RPS and RFS

[Marcelo Ricardo Leitner <marcelo.leitner@gmail.com>]

On Tue, Apr 12, 2016 at 02:50:45PM -0700, Tom Herbert wrote:
> On Tue, Apr 12, 2016 at 2:11 PM, Marcelo Ricardo Leitner
> <marcelo.leitner@gmail.com> wrote:
> > This patch adds what's missing to properly support RPS and RFS on SCTP,
> > as some of it is already implemented in common calls.
> >
> > Having support for RPS and RFS allows better scaling specially because
> > not all NICs support hashing SCTP headers.
> >
> > Save the hash right when we dequeue a skb from inqueue so we do it only
> > once per skb instead of per chunk. New sockets will then inherit the
> > hash through sctp_copy_sock().
> >
> > Signed-off-by: Marcelo Ricardo Leitner <marcelo.leitner@gmail.com>
> > ---
> >  net/sctp/inqueue.c | 3 +++
> >  net/sctp/socket.c  | 3 +++
> >  2 files changed, 6 insertions(+)
> >
> > diff --git a/net/sctp/inqueue.c b/net/sctp/inqueue.c
> > index 7e8a16c77039e1b70ef89f3e862dbb332bcc614f..b335ffcef0b901b0e71bf0843057dbf5877da31b 100644
> > --- a/net/sctp/inqueue.c
> > +++ b/net/sctp/inqueue.c
> > @@ -163,6 +163,9 @@ struct sctp_chunk *sctp_inq_pop(struct sctp_inq *queue)
> >                 chunk->singleton = 1;
> >                 ch = (sctp_chunkhdr_t *) chunk->skb->data;
> >                 chunk->data_accepted = 0;
> > +
> > +               if (chunk->asoc)
> > +                       sock_rps_save_rxhash(chunk->asoc->base.sk, chunk->skb);
> >         }
> >
> >         chunk->chunk_hdr = ch;
> > diff --git a/net/sctp/socket.c b/net/sctp/socket.c
> > index 878d28eda1a68dc639d7b9f3f663d7518f21bb32..36697f85ce48be39f41ddedd9f53369c7f9e28d8 100644
> > --- a/net/sctp/socket.c
> > +++ b/net/sctp/socket.c
> > @@ -6430,6 +6430,8 @@ unsigned int sctp_poll(struct file *file, struct socket *sock, poll_table *wait)
> >
> >         poll_wait(file, sk_sleep(sk), wait);
> >
> > +       sock_rps_record_flow(sk);
> > +
> >         /* A TCP-style listening socket becomes readable when the accept queue
> >          * is not empty.
> >          */
> > @@ -7186,6 +7188,7 @@ void sctp_copy_sock(struct sock *newsk, struct sock *sk,
> >         newsk->sk_lingertime = sk->sk_lingertime;
> >         newsk->sk_rcvtimeo = sk->sk_rcvtimeo;
> >         newsk->sk_sndtimeo = sk->sk_sndtimeo;
> > +       newsk->sk_rxhash = sk->sk_rxhash;
> >
> >         newinet = inet_sk(newsk);
> >
> HI Marcelo,
> 
> sock_rps_record_flow should probably be in sctp_poll also (like it is
> in tcp_poll).
> 
> Thanks,
> Tom

Hi Tom,

Yes, that's the middle chunk on this patch, no?

Note that for udp it's done after the actual poll, while for tcp it's
being saved before it. I went more udp-style on this one.

Thanks,
Marcelo