* Bennett Samowich <bsamow...@gmail.com> [120730 19:38]: > The problem exists even if I use the system's "/usr/bin/false" and > "/usr/bin/true" commands. > The problem exists even when PF is disabled or the only rule is "pass in". > > That being said the script itself is a simple host lookup against the > IP addresses to ensure the DNS server is actually resolving. Again, > just using "/usr/bin/false" or "/usr/bin/true" produces the same drop > in throughput. > > An example of the drop looks like this: > 9913Mbps > 9913Mbps > 7253Mbps <--- script interval point > 9913Mbps > 9913Mbps > ...etc... > > When the script is an actual shell script rather than /usr/bin/false, > the throughput drops spans the three seconds surrounding the time the > script runs. > 9913Mbps > 9913Mbps > 4321Mbps > 7253Mbps <--- script interval point > 5162Mbps > 9913Mbps > 9913Mbps
I'm not an expert, but AFAIU, on OpenBSD almost every syscall is executed under global kernel lock (please correct if I'm wrong), which can be the reason for what you're seeing here.
