netmap bridge can tranmit big packet in line rate ?

[Luigi Rizzo]

On Tue, May 21, 2013 at 06:51:12PM +0430, Hooman Fazaeli wrote:
> On 5/21/2013 5:10 PM, Barney Cordoba wrote:
> >
> > --- On Tue, 5/21/13, liujie <liujie at 263.net> wrote:
> >
> >> From: liujie <liujie at 263.net>
> >> Subject: Re: netmap bridge can tranmit big packet in line rate ?
> >> To: freebsd-net at freebsd.org
> >> Date: Tuesday, May 21, 2013, 5:25 AM
> >> Hi, Prof.Luigi RIZZO
> >>    
> >>  Firstly i should thank you for netmap. I tried to send a
> >> e-mail to you
> >> yestoday, but it was rejected.
> >>
> >>  I used two machines to test netmap bridge. all with i7-2600
> >> cpu and intel
> >> 82599 dual-interfaces card.
> >>
> >>  One worked as sender and receiver with pkt-gen, the other
> >> worked as bridge
> >> with bridge.c.
> >>
> >>  as you said,I feeled comfous too when i saw the big packet
> >> performance
> >> dropped, i tried to change the memory parameters of
> >> netmap(netmap_mem1.c
> >> netmap_mem2.c),but it seemed that  can not resove the
> >> problem.
> >>   60-byte packet send 14882289 pps  recv 
> >> 13994753 pps
> >>   124-byte     
> >>    send   8445770 pps 
> >> recv    7628942 pps
> >>   252-byte     
> >>    send   4529819 pps 
> >> recv     3757843 pps
> >>   508-byte     
> >>    send    2350815 pps 
> >> recv    1645647 pps
> >>   1514-byte       send 
> >>   814288 pps     recv  489133
> >> pps
> > These numbers indicate you're tx'ing 7.2Gb/s with 60 byte packets and
> > 9.8Gb/s with 1514, so maybe you just need a new calculator?
> >
> > BC
> > _______________________________________________
> >
> AsBarney pointed outalready, your numbers are reasonable. You have almost saturated
> the link with 1514 byte packets.In the case of 64 byte packets, you do not achieve line
> rate probably because of the congestion on the bus.Can you show us "top -SI" output on the
> sender machine?

the OP is commenting that on the receive side he is seeing a much
lower number than on the tx side (A:ix1 489Kpps vs A:ix0 814Kpps).

    [pkt-gen -f tx ix0]-->--[ix0 bridge ]
    [   HOST A        ]     [    HOST B ]
    [pkt-gen -f rx ix1]--<--[ix1        ]

What is unclear is where the loss occurs.

	cheers
	luigi