On Mon, 06 May 2024 18:17:48 +0800, Yi Wang wrote:
> From: Yi Wang <foxywang@xxxxxxxxxxx>
>
> We found that it may cost more than 20 milliseconds very accidentally
> to enable cap of KVM_CAP_SPLIT_IRQCHIP on a host which has many vms
> already.
>
> The reason is that when vmm(qemu/CloudHypervisor) invokes
> KVM_CAP_SPLIT_IRQCHIP kvm will call synchronize_srcu_expedited() and
> might_sleep and kworker of srcu may cost some delay during this period.
> One way makes sence is setup empty irq routing when creating vm and
> so that x86/s390 don't need to setup empty/dummy irq routing.
>
> [...]
Applied to kvm-x86 generic, with a lot of fixup. A sanity check on the end
result would be much appreciated. Thanks!
[1/3] KVM: Setup empty IRQ routing when creating a VM
https://github.com/kvm-x86/linux/commit/fbe4a7e881d4
[2/3] KVM: x86: Don't re-setup empty IRQ routing when KVM_CAP_SPLIT_IRQCHIP
https://github.com/kvm-x86/linux/commit/e3c89f5dd11d
[3/3] KVM: s390: Don't re-setup dummy routing when KVM_CREATE_IRQCHIP
https://github.com/kvm-x86/linux/commit/c4201bd24f4a
--
https://github.com/kvm-x86/linux/tree/next
