[ovs-dev] [PATCH v2] netdev-linux: Replace sendmsg with sendmmsg in netdev_linux_send

[Ben Pfaff]

On Fri, Jul 07, 2017 at 12:39:51AM +0000, Zhenyu Gao wrote:
> Sendmmsg can reduce cpu cycles in sending packets to kernel.
> Replace sendmsg with sendmmsg in function netdev_linux_send to send
> batch packets if sendmmsg is available.
> 
> If kernel side doesn't support sendmmsg, will fallback to sendmsg.
> 
>     netserver
> |------------|
> |            |
> |  container |
> |----veth----|
>           |
>           |        |------------|
>           |---veth-|   dpdk-ovs |      netperf
>                    |            |  |--------------|
>                    |----dpdk----|  | bare-metal   |
>                          |         |--------------|
>                          |              |
>                          |              |
>                         pnic-----------pnic
> 
> Netperf was consumed to test the performance:
> 
> 1)cmd:netperf -H remote-container -t UDP_STREAM -l 60 -- -m 1400
> result: netserver received 2383.21Mb(sendmsg)/2551.64Mb(sendmmsg)
> 
> 2)cmd:netperf -H remote-container -t UDP_STREAM -l 60 -- -m 60
> result: netserver received 109.72Mb(sendmsg)/115.18Mb(sendmmsg)
> 
> Sendmmsg show about 6% improvement in netperf UDP testing.
> 
> Signed-off-by: Zhenyu Gao <sysugaozhenyu at gmail.com>

After looking at this, I think that it might be best to simply include a
general-purpose sendmmsg implementation in the tree.  I sent out a
patch (although I haven't tested it):
        https://patchwork.ozlabs.org/patch/787344/

What do you think about implementing your change on top of this?