Is RHEL6 built with IRQ balancing within the kernel?

Linux now can be built with direct IRQ balancing support within the kernel, which eliminates the need for needing to run irqbalance. However, recent RHEL documentation and forum postings still reference using (or disabling) irqbalance ... including the RHEL 7 performance tuning manual.

Are the binary distributions for RHEL 6.x built with the IRQ balancing enabled within the kernel? I have not been able to find any definitive answer, yes or no.

If the IRQ balancing feature is enable in the kernel, would not running irqbalance be unnecessary, possibly redundant, and potentially a source of "thrashing" if conflicting behaviors were configured?

I also understand that in some cases, with IRQ balancing enabled in the kernel, some device driver initialization functions have problems, as some drivers try to be intelligent and use affinity when initializing the driver and may be unaware of conflicting IRQ balancing going on in the kernel, and/or irqbalance.

Is this a concern for RHEL 6.x?

Thanks for your help.

Dave B