PF queues break the 4 Gbps barrier
Contributed by Peter N. M. Hansteen on from the queueing for Terabitia dept.
OpenBSD's
PF
packet filter has long supported HFSC traffic shaping
with the 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.