OpenBSD 7.9 released on May 19, 2026 -- the 60th release in the project's history. Two additions are worth paying attention to if you run OpenBSD in any networking or routing capacity.
Heterogeneous CPU scheduling
Modern x86 and ARM chips ship with a mix of core types: high-performance cores, efficiency cores, and sometimes SMT siblings. OpenBSD 7.9 adds a mechanism to tell the scheduler which cores to use and which to leave alone.
The new hw.blockcpu sysctl takes a four-letter sequence: S (SMT), P (performance), E (efficiency, roughly 50-80% speed), L (lethargic). Setting this lets you exclude specific core types from the scheduler. Currently works on amd64 and arm64.
This is useful in edge routing scenarios where you want predictable latency and prefer to hand certain cores to specific workloads. It is not autopilot -- you are telling the kernel what to avoid, not what to optimize for.
Socket splicing improvements
Socket splicing is a kernel mechanism that moves data between two network sockets without copying through userspace. The data path goes kernel to kernel, bypassing the syscall overhead of read/write cycles. OpenBSD 7.9 unlocks socket splicing to work across multiple processors simultaneously -- previously there were serialization constraints that limited throughput on multi-core systems.
For anything using OpenBSD as a proxy or traffic forwarder, this is a meaningful improvement. If you run relayd or a custom socket-based forwarding setup, the ceiling just got higher.
Other changes
The release also adds basic 802.11ax (Wi-Fi 6) support and expands VMM virtualization capabilities. Driver improvements cover multiple architectures.
The release ships on the project's fixed six-month cycle. OpenBSD's release cadence is one of the things that makes it predictable in production -- you know when the next one is coming and roughly what level of change to expect.
Worth watching: whether the socket splicing throughput improvements show up in community benchmarks for relayd-based setups.
Sources: OpenBSD 7.9 release page