From: Vitaliy Makkoveev <mvs@openbsd.org>
Subject: Re: UDP parallel input
To: Alexander Bluhm <bluhm@openbsd.org>
Cc: tech@openbsd.org
Date: Wed, 24 Jul 2024 11:44:29 +0300

On Tue, Jul 23, 2024 at 03:40:21PM +0200, Alexander Bluhm wrote:
> Hi,
> 
> mvs@ has completed the final bits to make socket buffer MP safe for
> UDP packets.  This means that we can run UDP input on multiple
> threads.  Diff below activates this.
> 
> Usually IP processing runs on multiple softnet threads with shared
> net lock.  From there local packets are queued and processed by one
> thread with exclusive net lock.  If the PR_MPINPUT flag is set,
> protocol input is called directly from IP input on multiple threads,
> shared net lock and no additional queueing.
> 
> Note that you need kernel sources from at least Sun Jul 21.  Then
> apply this diff and test UDP local delivery to sockets.  To see an
> performance effect, you need multiple CPUs and network interfaces
> that support multiqueue.  These are bnxt, igc, ix, ixl, ngbe, vmx.
> 
> Please test!
> 

ok mvs

> bluhm
> 
> Index: netinet/in_proto.c
> ===================================================================
> RCS file: /data/mirror/openbsd/cvs/src/sys/netinet/in_proto.c,v
> diff -u -p -r1.106 in_proto.c
> --- netinet/in_proto.c	13 Jul 2024 12:00:11 -0000	1.106
> +++ netinet/in_proto.c	22 Jul 2024 11:40:55 -0000
> @@ -185,7 +185,7 @@ const struct protosw inetsw[] = {
>    .pr_type	= SOCK_DGRAM,
>    .pr_domain	= &inetdomain,
>    .pr_protocol	= IPPROTO_UDP,
> -  .pr_flags	= PR_ATOMIC|PR_ADDR|PR_SPLICE|PR_MPSOCKET,
> +  .pr_flags	= PR_ATOMIC|PR_ADDR|PR_SPLICE|PR_MPINPUT|PR_MPSOCKET,
>    .pr_input	= udp_input,
>    .pr_ctlinput	= udp_ctlinput,
>    .pr_ctloutput	= ip_ctloutput,
> Index: netinet6/in6_proto.c
> ===================================================================
> RCS file: /data/mirror/openbsd/cvs/src/sys/netinet6/in6_proto.c,v
> diff -u -p -r1.116 in6_proto.c
> --- netinet6/in6_proto.c	19 Jul 2024 16:58:32 -0000	1.116
> +++ netinet6/in6_proto.c	22 Jul 2024 11:40:55 -0000
> @@ -136,7 +136,7 @@ const struct protosw inet6sw[] = {
>    .pr_type	= SOCK_DGRAM,
>    .pr_domain	= &inet6domain,
>    .pr_protocol	= IPPROTO_UDP,
> -  .pr_flags	= PR_ATOMIC|PR_ADDR|PR_SPLICE|PR_MPSOCKET,
> +  .pr_flags	= PR_ATOMIC|PR_ADDR|PR_SPLICE|PR_MPINPUT|PR_MPSOCKET,
>    .pr_input	= udp_input,
>    .pr_ctlinput	= udp6_ctlinput,
>    .pr_ctloutput	= ip6_ctloutput,
>