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

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Date:	Tue, 12 Apr 2016 14:58:48 -0700
From:	Tom Herbert <tom@...bertland.com>
To:	Marcelo Ricardo Leitner <marcelo.leitner@...il.com>
Cc:	Linux Kernel Network Developers <netdev@...r.kernel.org>,
	Neil Horman <nhorman@...driver.com>,
	Vlad Yasevich <vyasevich@...il.com>, linux-sctp@...r.kernel.org
Subject: Re: [PATCH] sctp: add support for RPS and RFS

On Tue, Apr 12, 2016 at 2:57 PM, Marcelo Ricardo Leitner
<marcelo.leitner@...il.com> wrote:
> 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@...il.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@...il.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.
>

Yes, I missed that.

> Thanks,
> Marcelo