Quick definition Kernel bypass is a technique where applications access network hardware directly, bypassing the operating system kernel. This reduces latency by eliminating OS overhead, achieving latencies under 10 microseconds. What it is Normally, when an application sends network data, it asks the OS kernel to handle the transmission. The kernel performs checks, manages buffers, and schedules the transmission. This overhead adds latency. Kernel bypass libraries (like DPDK or solarflare) allow applications to access network hardware directly. The application manages buffers and transmission scheduling itself. Why it matters For HFT, sub-microsecond latency can mean the difference between profit and loss. Kernel bypass technologies reduce latency from 1-10 microseconds (kernel-based) to 100-500 nanoseconds (kernel bypass). This tiny advantage, repeated across millions of trades, adds up to significant profit for HFT firms. Latency breakdown A typical network round-trip with kernel overhead: 5-10 microseconds. With kernel bypass: 500-1000 nanoseconds. The difference is 5-10 times faster. Practical implementation An HFT firm co-locates servers at an exchange and uses kernel bypass technology. They achieve latencies so low that they can profitably trade opportunities that exist for only a few microseconds. Complexity Kernel bypass requires expertise and custom development. It is not available to most traders. Only well-funded HFT firms can justify the investment. Use cases Kernel bypass is used by: - HFT firms trading derivatives and equities - Crypto exchanges optimising latency - Financial infrastructure companies - Financial data providers Limitations Kernel bypass is extremely low-level programming. It bypasses OS protections and can be unstable. It also makes deployment and debugging harder. See also - Latency - Co-location - High-Frequency Trading - DPDK (Data Plane Development Kit)
