udp v6 early demux?

udp v6 early demux?

[Vlad Yasevich]

Hi

While testing udpv6 lockless path, I noticed that there is no
support for udpv6 early demux?  Is there a technical reason why,
or was this just something that got forgotten (kind of like
lockeless sendmsg)?

Thanks
-vlad

Re: udp v6 early demux?

[Eric Dumazet]

On Tue, 2015-02-10 at 12:14 -0500, Vlad Yasevich wrote:
> Hi
> 
> While testing udpv6 lockless path, I noticed that there is no
> support for udpv6 early demux?  Is there a technical reason why,
> or was this just something that got forgotten (kind of like
> lockeless sendmsg)?

If you have a use case for connected UDP ipv6 flows with performance
issues, then you might add early demux I guess.

IPv4 udp early demux has been a bit of a hack actually,
as Shawn main usage was multicast AFAIK

63c6f81cdde5 udp: ipv4: do not waste time in __udp4_lib_mcast_demux_lookup
610438b74496 udp: ipv4: fix potential use after free in udp_v4_early_demux()
f69b923a758f udp: fix a typo in __udp4_lib_mcast_demux_lookup
421b3885bf6d udp: ipv4: Add udp early demux

Re: udp v6 early demux?

[Vlad Yasevich]

On 02/10/2015 12:32 PM, Eric Dumazet wrote:
> On Tue, 2015-02-10 at 12:14 -0500, Vlad Yasevich wrote:
>> Hi
>>
>> While testing udpv6 lockless path, I noticed that there is no
>> support for udpv6 early demux?  Is there a technical reason why,
>> or was this just something that got forgotten (kind of like
>> lockeless sendmsg)?
> 
> If you have a use case for connected UDP ipv6 flows with performance
> issues, then you might add early demux I guess.
> 
> IPv4 udp early demux has been a bit of a hack actually,
> as Shawn main usage was multicast AFAIK
> 
> 63c6f81cdde5 udp: ipv4: do not waste time in __udp4_lib_mcast_demux_lookup
> 610438b74496 udp: ipv4: fix potential use after free in udp_v4_early_demux()
> f69b923a758f udp: fix a typo in __udp4_lib_mcast_demux_lookup
> 421b3885bf6d udp: ipv4: Add udp early demux
> 
> 

I was more wondering if we can avoid the route the lookup.  It may not always be
a connected a case.  If you have multiple senders and a single receiver on the
same subnet, avoiding the route lookup with early demux might help.

-vlad

Re: udp v6 early demux?

[Eric Dumazet]

On Tue, 2015-02-10 at 21:53 -0500, Vlad Yasevich wrote:

> I was more wondering if we can avoid the route the lookup.  It may not always be
> a connected a case.  If you have multiple senders and a single receiver on the
> same subnet, avoiding the route lookup with early demux might help.

Yes, but early demux requires a connected socket, sorry.