[Xen-devel] irqbalance?

[pak333@xxxxxxxxxxx]

Hi All,

 

If I turn off irqbalance xen/arch/x86/irq.c, does that actually stop XEN from balancing irqs across different physical cpus, or will that override the setting if there are too many interrupts and one of the cpus is overloaded.

 

Example: i have 4 cpus and i have configured irqbalance= off, so there is no irqbalancing done by xen.

 

Now if i have affintized all my physical interrutps to one cpu say cpu1 all the interrutps shpuld be handled by the cpu1 and so should all the softirqs generated.

Now what happens if one of the other cpus is lightly loaded, will some of the softirqs be queued against the other cpus or will cpu1 handle all interrupts and softirqs.

 

Looks to me like there are two levels of interrupt redirection, one done by the hardware where each physical device interrupt is assigned to a particual processor dynamically and then on top of that is the irqbalancing done by Xen itself. Is that true? and irqbalance=off only affects the latter and interrupt affinitzation is for the former?

 

 

Thanks

Prabha

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