Subject: Re: [net-next 0/3] Improve UDP multicast receive latency

From: Veaceslav Falico <[email-masked]>
Date: Tue, 1 Oct 2013 22:21:42 +0200

On Tue, Oct 01, 2013 at 02:33:42PM -0500, Shawn Bohrer wrote:
>The removal of the routing cache in 3.6 had impacted the latency of our
>UDP multicast workload.  This patch series brings down the latency to
>what we were seeing with 3.4.
>
>Patch 1 "udp: Only allow busy read/poll on connected sockets" is mostly
>done for correctness and because it allows unifying the unicast and
>multicast paths when a socket is found in early demux.  It can also
>improve latency for a connected multicast socket if busy read/poll is
>used.
>
>Patches 2&3 remove the fib lookups and restore latency for our workload
>to the pre 3.6 levels.
>
>Benchmark results from a netperf UDP_RR test:
>3.11 kernel   90596.44 transactions/s
>3.11 + series 91792.70 transactions/s
>
>Benchmark results from a fio 1 byte UDP multicast pingpong test
>(Multicast one way unicast response):
>3.11 kernel   12.647us RTT
>3.11 + series 12.233us RTT
>
>Shawn Bohrer (3):
>  udp: Only allow busy read/poll on connected sockets
>  udp: Add udp early demux
>  net: ipv4 only populate IP_PKTINFO when needed
>
> include/net/ip.h       |    2 +-
> include/net/sock.h     |    2 +-
> include/net/udp.h      |    1 +
> net/ipv4/af_inet.c     |    1 +
> net/ipv4/ip_sockglue.c |    5 +-
> net/ipv4/raw.c         |    2 +-
> net/ipv4/udp.c         |  160 +++++++++++++++++++++++++++++++++++++++++------
> net/ipv6/udp.c         |    5 +-
> 8 files changed, 150 insertions(+), 28 deletions(-)
>
>-- 
>1.7.7.6
>
>
>-- 
>
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It's not a good idea to send patches with that kind of footer, afaik.

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