On 2014-12-02, Darren Tucker <dtuc...@zip.com.au> wrote: > On Fri, Nov 28, 2014 at 6:32 PM, Blaise Hizded <bla...@ovh.fr> wrote: >> >> I run the previous generation ALIX 2D13 with OpenBSD 5.6 on it for a >> home firewall with 10MB WAN broadband and 100MB between computers. >> All is fine: low temperature, low consumption, same speed as with a >> basic 100MBB switch. >> > > I spent some time tuning the vr(4) driver on ALIX a while back[1], and in > my experience the throughput maxes out at around 85 Mbit/s of TCP (ie > iperf) traffic through it. I don't know what the limiting factor is, but > it's not CPU. My guess is it's the checksum offload hardware in the chips, > in which case doing those in software would be faster at the cost of using > more CPU, but I never tested this theory. > > [1] http://undeadly.org/cgi?action=article&sid=20130201054156 >
Linux developers were seeing higher throughput (though obviously higher cpu usage) when offload was disabled. Apparently the checksum offload can't pipeline. I'm not sure if vlan hw tagging was also implicated. IIRC there were more details in an old lkml post.
