* ML mail <mlnos...@yahoo.com> [2015-02-18 23:32]: > Stupid question but if you would have to choose between two different > Intel CPUs for an OpenBSD firewall using 4 to 6 Intel NICs with all /24 > networks behind and around 50-60 Mbit/s average traffic would you > rather choose the CPU with higher Frequency and less cores or for a CPU > with lower frequency but more cores?
The #1 criteria is memory bandwidth and even more so latency. Thus, more cache helps. Then it's the speed of a single core. Our kernel is mostly biglocked still, so almost everything is going to run on CPU (core) 0. There is ongoing work to unlock at least parts of the network stack to profit from multiple cores, but that doesn't help you right now, and even then I'd be super surprised if the faster cores wouldn't win against more cores, pushing packets isn't one of the workloads that is well suited for MP, due to quite a lot of shared data structures (think routing table, pf state table, ...). > For example: > - E5-2630Lv3, 20M Cache, 1.80 GHz, 8 cores: > - E5-2637v3, 15M Cache, 3.50 GHz, 4 cores: the latter. -- Henning Brauer, h...@bsws.de, henn...@openbsd.org BS Web Services GmbH, http://bsws.de, Full-Service ISP Secure Hosting, Mail and DNS. Virtual & Dedicated Servers, Root to Fully Managed Henning Brauer Consulting, http://henningbrauer.com/
