OpenBSD: PF queues break the 4 Gbps barrier

queue rules in pf.conf(5). However, an internal 32-bit limitation in the HFSC service curve structure (struct hfsc_sc) meant that bandwidth values were silently capped at approximately 4.29 Gbps, the maximum value of a u_int. With 10G, 25G, and 100G network interfaces now commonplace, OpenBSD devs making huge progress unlocking the kernel for SMP, and adding drivers for cards supporting some of these speeds, this limitation started to get in the way. Configuring bandwidth 10G on a queue would silently wrap around, producing incorrect and unpredictable scheduling behaviour. A new patch widens the bandwidth fields in the kernel's HFSC scheduler from 32-bit to 64-bit integers, removing this bottleneck entirely. The diff also fixes a pre-existing display bug in pftop(1) where bandwidth values above 4 Gbps would be shown incorrectly. For end users, the practical impact is: PF queue bandwidth configuration now works correctly for modern high-speed interfaces. The familiar syntax just does what you'd expect: queue rootq on em0 bandwidth 10G queue defq parent rootq bandwidth 8G default. Values up to 999G are supported, more than enough for interfaces today and the future. Existing configurations using values below 4G continue to work - no changes are needed. As always, testing of -current snapshots and donations to the OpenBSD Foundation are encouraged. The editors note that the thread titled PF Queue bandwidth now 64bit for >4Gbps queues on tech@ has the patch and a brief discussion with the conclusion that the code is ready to commit by Friday, March 20th, 2026.