Hi,

We were confused with the behavior of interrupt distribution across CPUs in
Qemu guest VM.

We were using Qemu-kvm 1.1.2 and OSes of the both guest and host were
CentOS 6.5. We found that the interrupts were evenly distributed as long as
the number of CPU cores were no more than 8. Otherwise, the interrupts all
went to CPU0.

Furthermore, if we turned off kernel_irqchip explicitly, i.e. setting
kernel_irqchip=off, no matter how many CPU cores the VM had, the interrupts
all went to CPU0.

Further, when we tested on qemu 2.1.3, the interrupts were always
unbalanced.

I'm wondering why this happened? How to achieve balance interrupts in guest
VM?

Many thanks for your advice.

Jian Qiu

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