Re: ksoftirqd 100% after disabling IPv4 route cache on high pps.

On Wed, 2012-12-05 at 13:22 -0800, 叶雨飞 wrote:

Hi Eric,

After disabling the route cache, I found a forwarding performance
problem (inevitable ?). Basically the kernel couldn't keep up under
about 100k pps and ksoftirqd is dominating the CPU. This problem went
away right away if I do

echo  1 > rt_cache_rebuild_count

and comes back as soon as i do echo -1 > rt_cache_rebuild_count.

I then tried to use RPS/RFS to share the load on to mulitple cpus
(since ksoftirqd is only using 1 core, clearly). but that has little
effect.

Is there some tweaks/patches you recommend?

Yes, upgrade your kernel to 3.6 or 3.7, this problem has been solved for
good. No more IP route cache and good performance.