[RFC] irqbalance: Mark in-kernel irqbalance as obsolete, set to N by default

We've recently seen a number of user bug reports against e1000 that the 
in-kernel irqbalance code is detrimental to network latency. The algorithm 
keeps swapping irq's for NICs from cpu to cpu causing extremely high network 
latency (>1000ms). Another NIC driver (cxgb) already has severe warnings in 
their documentation file against using CONFIG_IRQBALANCE, but this is a 
general problem for all NIC drivers and other subsystems. This is especially 
so with cpufreq scaling where the system is slowed down and the migrations 
take much longer.

I suggest that the in-kernel irqbalance is phased out, by marking it OBSOLETE 
first and (perhaps) removing the code later. The userspace irqbalance daemon 
written by Arjan van de Ven does a wonderful job and should be used instead.

Signed-off-by: Auke Kok <redacted>

---

  Kconfig |   15 +++++++++++----
  1 file changed, 11 insertions(+), 4 deletions(-)
---