kperf

kperf is a an iperf/netperf replacement with a more fine-grained worker control. Modern NICs have multiple Rx queues and while iperf / netperf can bind to a CPU they are not aware of which CPU is serving the Rx queue selected by the NIC for the flow. If the NIC does not support flow steering this is a problem. kperf asks the kernel which CPU is used for Rx and can bind itself appropriately (same core, Rx core + N, etc.). For parallel runs it can also make sure that the flows are not colliding (being served by the same CPU).

Other strengths include:

• RPC-like traffic (unlike iperf);
• kTLS support (just data, no control records);
• more stats (TCP, latency, CPU use).

That said, kperf is more of hackable library than a ready-to-use Swiss army knife. There is an example client application provided but the number of configurations is so high it seems impossible to write a comprehensive client controlled solely by command line options.

High level design

Client does not generate any traffic, it only orchestrates load between Servers.

When Client connect to a Server Server spawns a Session which is what Client controls on the server side. There can be multiple concurrent Sessions within one Server, there are no limitations. Note that Session is between Client and one Server, it can contain connections to many other Sessions. Each Session is a separate process.

Session can establish Connections with other Sessions.

Session can spawn Workers which is what drivers the IO.

Connections are established within Sessions, not Workers because Workers and Connections are usually assigned once it's known which CPU given connection lands on.

Currently only Process Workers are supported (each worker is a separate process), adding threads should not be a problem but was not needed, so far:

                             .--------.
                       .-----| Client |----.
                       |     '--------'    |
                       |                   |
 ----------------------|------       ------|---------------------
                       v      |     |      v
   .--------.     .---------. |     | .---------.     .--------.
   | Server |-----| Session | |     | | Session |-----| Server |
   '--------'     '---------' |     | '---------'     '--------'
                       |      |     |      |
                       v      |     |      v
                  .---------. |     | .---------.
                  | Worker  | |     | | Worker  |
                  '---------' |     | '---------'
Host A            .---------. |     | .---------.        Host B
                  | Worker  | |     | | Worker  |
                  '---------' |     | '---------'
                  .---------. |     | .---------.
                  | Worker  | |     | | Worker  |
                  '---------' |     | '---------'
                              |     |

Contributing

Please refer to relevant details in the license, code of conduct, and contributing guide.

Per Meta's policies contributors are required to submit a CLA.