packet generator

[Andrew Gallatin]

Don Bowman writes:
 > From: owner-freebsd-net at freebsd.org
 > > [mailto:owner-freebsd-net at freebsd.org]On Behalf Of Andrew Gallatin
 > > Sent: September 10, 2004 19:08 PM
 > > To: freebsd-net at freebsd.org
 > > Subject: packet generator
 > > 
 > > Does anybody have a free, in-kernel tool to generate packets quicky
 > > and send them out a particular etherent interface on FreeBSD?
 > > Something similar to pktgen on linux?
 > > 
 > > I'm trying to excersize just the send-side of programmable firmware
 > > based NIC.  The recieve side of the NIC firmware is not yet written,
 > > but I want to get started tuning and shaking the bugs out of the send
 > > side while the firmware author does the recieve path.  The packets
 > > just get dropped on the floor by the NIC, so its a good way to test
 > > the interface..
 > > 
 > 
 > ng_source was a netgraph module we wrote and contributed.
 > It can transmit ~800Kpps on a PCI-X system. The code is in
 > src/sys/netgraph/ng_source.c.

I finally figured out that ngctl shutdown mx0:orphans will get things reset
enough so that I can re-run the test.  

I send 1.6 million packets and set things up so that I see 
these stats at the end:

Args:   { outOctets=102400000 outFrames=1600000 queueOctets=64
queueFrames=1 startTime={ tv_sec=1095109553 tv_usec=628521 } endTime={
tv_sec=1095109557 tv_usec=546685 } elapsedTime={ tv_sec=3 tv_usec=918164 } }

If I put counters in my driver's xmit routine, I see that my driver's
xmit routine was called 683441 times.  This means that the queue was
only a little over two packets deep on average, and vmstat shows idle
time.  I've tried piping additional packets to nghook mx0:orphans
input, but that does not seem to increase the queue depth.

My default send queue maxlen is 255 (hw send fifo size) and I (think)
I see ng_source increasing it:

  ng_source: changing ifq_maxlen from 255 to 4096

Hmm.. I wonder if I need to increase hz..

Thanks,

Drew