UDP/TCP versus IP frames - subtle out of order packets with hardware hashing

[Slawa Olhovchenkov]

On Tue, Jul 15, 2014 at 07:33:57AM -0700, Adrian Chadd wrote:

> On 15 July 2014 04:33, Slawa Olhovchenkov <slw at zxy.spb.ru> wrote:
> > On Tue, Jul 15, 2014 at 03:22:34PM +0430, Hooman Fazaeli wrote:
> >
> >> On 7/15/2014 2:01 PM, Slawa Olhovchenkov wrote:
> >> > On Tue, Jul 15, 2014 at 01:31:52PM +0430, Hooman Fazaeli wrote:
> >> >
> >> >> Doesn't the problem applies to TCP too?
> >> >> TCP may be fragmented too but is less likely because of MSS.
> >> > Don't forget GRE, IPIP, ESP and AH!
> >> >
> >> These protocols don't use port numbers  and the RSS hash is computed based on the
> >> (srcip,dstip) tuple, so the problem does not apply to them.
> >
> > And all flows go to one queue? Bad.
> 
> All the packets between two IP addresses for non-TCP, non-UDP get
> hashed to the same CPU core, yes.
> 
> If you have 1000 IP tunnels to different end-hosts, they'll be on
> different CPUs.

What about two host, 10G link and 1000 TCP connections over IPsec?