Messages in this thread | | | Date | Mon, 11 May 2015 13:25:22 +0200 | From | Joerg Roedel <> | Subject | Re: [PATCH] kvm: irqchip: Break up high order allocations of kvm_irq_routing_table |
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Hi Paolo,
On Fri, May 08, 2015 at 06:26:13PM +0200, Paolo Bonzini wrote: > It probably doesn't matter much indeed, but can you time the difference? > kvm_set_irq_routing is not too frequent, but happens enough often that > we had to use a separate SRCU instance just to speed it up (see commit > 719d93cd5f5, kvm/irqchip: Speed up KVM_SET_GSI_ROUTING, 2014-01-16).
The results vary a lot, but what I can say for sure is that the kvm_set_irq_routing function takes at least twice as long (~10.000 vs ~22.000 cycles) as before on my AMD Kaveri machine (maximum was between 3-4 times as long).
On the other side this function is only called 2 times at boot in my test, so I couldn't detect a noticable effect on the overall boot time of the guest (37 disks were attached).
Joerg
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