Re: [PATCH] locking/paravirt: Fix performance regression on core bonded vCPU

[Juergen Gross]

On 03.11.22 14:58, johnnyaiai wrote:
> Thanks for reply! I think nopvspin parameters controls
> pvspinlock or native spinlock. a vm guest always running
> on virtspin wheather nopvspin sets or not when EXITS_HALT
> not supported by hypervisor. So provide a missing parameter
> 'novirtspin'.

Your patch is doing:

    static_branch_disable(&virt_spin_lock_key);

in case your parameter has been specified.

When running as Xen guest the related coding is doing:

    static_branch_disable(&virt_spin_lock_key);

Only when running as KVM guest there is a difference, but this could be changed
by modifying kvm_spinlock_init().

Having two parameters with the same or very similar semantics is not a good
idea IMO.


Juergen

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