Libtpa(Transport Protocol Acceleration) is a DPDK based userspace TCP stack implementation.

Libtpa is fast. It boosts the redis benchmark performance more than 5 times, from 0.21m rps to 1.14m rps. Meanwhile, the p99 latency is greatly decreased, from 0.815ms to 0.159ms.

Libtpa is also sort of stable, all kudos to the comprehensive testing. Libtpa has more than 200 tests. Together with the testing arguments matrix, it can result in a big variety of test cases. Therefore, most of the bugs are captured before deployment.

⚠️ Although libtpa has been tested heavily inside Bytedance data center, it's still recommended to run as much testing as you can before deployment, for libtpa is still under active development and it's just v1.0-rc0 being released. Tons of changes have been made since the last stable release.

There are two things that might be kind of special about libtpa.

The first one is that libtpa is an embedded TCP stack implementation that supports run-to-completion mode only. It creates no datapath thread by itself. Instead, it's embedded in the application thread.

The other special thing about libtpa is that it's not a standalone TCP/IP stack implementation. Instead, it lives together with the host TCP/IP stack: libtpa just takes control of the specific TCP connections needed to be accelerated. Taking redis as an example, if redis is accelerated by libtpa, then all TCP connections belonging to redis will go to libtpa. All other connections (TCP or none TCP, such as UDP) go to where it belongs: the host stack.

There is a huge advantage about that. If libtpa crashes, except the application accelerated by libtpa is affected, none other workloads would be affected.

Having said that, it requires some special support from NIC. Section Requirements gives a bit more information about that.

Due to the novel design described above (to just accelerate some specific TCP connections), libtpa requires flow bifurcation support from NIC.

Most NICs have flow bifurcation support with the help of SR-IOV. But they require some internal DPDK/Linux patches (or even firmwares) to satisfy the libtpa needs.

On the other hand, Mellanox NIC has native flow bifurcation support that doesn't require SR-IOV. More importantly, it doesn't require any internal stuff. Libtpa works well with Mellanox NIC just with the upstream DPDK.

Therefore, libtpa currently only supports Mellanox NIC.

You might want to check below docs for more detailed information:

• quick start guide
• user guide
• programming guide
• contribution guide
• internals