What to do about high IRQ usage?
My interrupt usage is often averaging around 50% and spiking higher on my Alix 2d3 system (which has Via VT6105M 10/100 network cards). I am using it has a VPN concentrator, currently with 81 active Phase 2s.
Would disabling the 'Disable hardware TCP segmentation offload' and 'Disable hardware large receive offload' options be advisable, or make any difference? Would switching VPN tunnels from 3DES to AES make a difference (I currently have no hardware acceleration)? Other than interrupt, my CPU usage is low.
With that many connections on that weak of a CPU, I wouldn't expect anything better especially depending on how much traffic you're pushing through your 81 active P2s. That's a class of hardware you'd find software-restricted to 5 or 10 VPNs on commercial firewalls. Nothing you change will make any difference, the crypto cards perform the same regardless of which cipher (assuming you're talking about a hifn, if it's the onboard glxsb, you can only use AES 128 with it).