"Why is the softirq handling behaviour different in both machines."
One possibility could be that the two machines have different kernels. If one computer has Intel CPUs and the other has AMD CPUs then Red Hat probably installed two different kernels on the two machines. Check /boot on each machine for the name of the kernel that machine is running. As a byproduct of having two different kernels, some of the kernel parameters such as whether to use softrqes may have been compiled differently by Red Hat. You can probably standardize your two kernels more if you compile your own.
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