Messages in this thread | | | Date | Mon, 19 Dec 2011 10:16:39 +0900 | From | Takuya Yoshikawa <> | Subject | Re: [PATCH v4] kvm: make vcpu life cycle separated from kvm instance |
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Liu ping fan wrote: > Suppose the following scene, > Firstly, creating 10 kvm_vcpu for guest to take the advantage of > multi-core. Now, reclaiming some of the kvm_vcpu, so we can limit the > guest's usage of cpu. Then what about the kvm_vcpu unused? Currently > they are just idle in kernel, but with this patch, we can remove them.
Then why not write it in the changelog?
>>> +void kvm_arch_vcpu_zap(struct work_struct *work) >>> +{ >>> + struct kvm_vcpu *vcpu = container_of(work, struct kvm_vcpu, >>> + zap_work); >>> + struct kvm *kvm = vcpu->kvm; >>> >>> - atomic_set(&kvm->online_vcpus, 0); >>> - mutex_unlock(&kvm->lock); >>> + kvm_clear_async_pf_completion_queue(vcpu); >>> + kvm_unload_vcpu_mmu(vcpu); >>> + kvm_arch_vcpu_free(vcpu); >>> + kvm_put_kvm(kvm); >>> } >> >> zap is really a good name for this? >> > zap = destroy, so I think it is OK.
Stronger than that. My dictionary says "to destroy sth suddenly and with force."
In the case of shadow pages, I see what the author wanted to mean by "zap".
In your case, the host really destroy a VCPU suddenly? The guest have to unplug it before, I guess.
If you just mean "destroy", why not use it?
>>> +#define kvm_for_each_vcpu(vcpu, kvm) \ >>> + list_for_each_entry_rcu(vcpu,&kvm->vcpus, list) >> >> Is this macro really worth it? >> _rcu shows readers important information, I think. >> > I guest kvm_for_each_vcpu is designed for hiding the details of > internal implement, and currently it is implemented by array, and my > patch will change it to linked-list, > so IMO, we can still hide the details.
Then why are you doing list_add_rcu(&vcpu->list, &kvm->vcpus); without introducing kvm_add_vcpu()?
You are just hiding part of the interface. I believe this kind of incomplete abstraction should not be added.
The original code was complex enough to introduce a macro, but list_for_each_entry_rcu(vcpu, &kvm->vcpus, list) is simple and shows clear meaning by itself.
Takuya
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