Hi Dennis,
> Now from what I read on the net about haproxy I expected that the > load-balancing isn't that cpu intensive and that most of the cpu usage > should be generated by the ssl offloading but what I'm seeing is that > the two cores 0 and 4 are at 20% idle while the rest is at 80-90% idle > and that cpu core 4 shows 20% soft interrupt usage while all other cores > show 0% soft interrupt usage. The statistics page also shows an idle > time of only 20%. This sounds to me like a kernel thing. What exact kernel are you using? If you are on CentOs6, you should give CentOs 7 a try (which has a 3.10 kernel). There is probably some low level kernel/irq tuning that could help in this situation as well, but I never did it. Regards, Lukas