[c-nsp] IPerf alternative

Nitzan Tzelniker nitzan.tzelniker at gmail.com
Tue Aug 8 00:12:12 EDT 2017

If you need DPDK based statefull and also HTTP tests take a look on


On Tue, Aug 8, 2017 at 12:34 AM, James Bensley <jwbensley at gmail.com> wrote:

> On 7 August 2017 at 11:40, Raymond Burkholder <ray at oneunified.net> wrote:
> >
> >  on some platforms, like linux, you need to check ‘ethtool -S’ to see if
> the  operating system is dropping packets (on tx or rx).  which may require
> some performance tuning of the network interfaces.
> Yeah ethtool -C is import to set the minimum RX IRQ (NET_RX) as low as you
> can.
> Without using one of the third party libraries like Netmap, DPDK or
> VPP, or similar to implement Kernel bypass techniques, or a tool that
> uses them, you have to make lots of “tweaks” to get even a fraction of
> that bandwidth or pps rates. EtherateMT uses Tx and Rx ring buffers
> (using PACKET_MMAP_TX/PACKET_MMAP_RX), with AF_PACKET to dump the ring
> with a single syscall and single context switch, it forcefully
> increases the OS socket send/receive buffer size, it uses
> PACKET_QDISC_BYPASS to bypass the Linux queuing discipline sub-system
> (skipping and QoS configuration basically), it ignores dropped packets
> using PACKET_LOSS, and can use FANOUT groups to spray traffic over all
> Tx/Rx queues in the NIC. One can also use isolcpus and nohz_full. I
> have some noted on host tuning I can share if anyone is interested,
> I’d just need to dig them out. However even with all those, DPDK et al
> are still much faster.
> > also, on a linux platform, the kernel guys use some trace tools, one of
> which will create one buffer, and copy it to the network interface, making
> a very effective high bandwidth tester, with some purporting to fill a 10g
> link.  I don’t have the name off the top of my head.
> You might be thinking of pktgen (the Kernel module and not the DPDK
> based app!) which I believe can do 10Gbps using 64 byte packets. I
> think (could be wrong here) over the years that morphed into trafgen
> in the netsniff package: http://netsniff-ng.org/
> By loading it into the kernel there is arguably one less copy from
> user land process into kernel memory (as is the case with sendto() for
> example; https://linux.die.net/man/2/sendto) and but using ring
> buffers one syscall can be used to send or receive many packets from
> the user land process into sk_buffs in Kernel memory and into DMA
> space. DPDK uses similar ideas but it has something called the EAL
> (environment abstraction layer) which can provide XSS within minimal
> effort from the user and it can use it can DMA directly from it’s ring
> buffer removing another copy-per-packet over Linux’s AF_PACKET module
> (as well as loads of other cool shit).
> VPP which builds on DPDK recently passed the 1Tbps mark (10x100Gbps
> interfaces with like 1M routes in FIB) using the new Intel SkyLake
> CPU. They have achieved a PPS budget per packet that was stupidly low,
> like 200 instructions per packet.
> > this being a cisco list, some cisco platforms have built in ttcp
> performance testers.
> I always forget about that but I've never had a particularly great
> experience with it. It's there on some ISR models, I also used it on
> the ME3x00 switches once, but the throughput was like 20Mbps and I
> found it quite flaky.
> I think I'm hijacking this thread a bit with my own rants.
> Sorry about that,
> James.
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