Sidestep Kernel with RDMA

Remote Direct Memory Access - or RDMA for short - allows machines to access memory of other machines without going through the operating system kernel.  

This is a traditional computer science trick - if you have an abstraction in the way of your objective, bypass the abstraction.

The idea is to get performance improvement - low latency and high throughput. Sometimes these tricks come under the label of "ultra-low-latency software development" or "ultra low latency techniques".

The goal is zero-copy (or near-zero-copy) data transfer - data moves between memory buffers directly. 

Key benefits include:

• Skipping kernel involvement
• Avoid creation of multiple intermediate copies
• Avoid switching between kernel space and user space

Protocols to support this include:

• InfiniBand
• RoCE (RDMA over Converged Ethernet)
• iWARP (RDMA over TCP/IP).

Protocols need to be supported at the OS level. Microsoft Windows Server 2012 onwards for example support iWARP.