| Date | Wed, 29 Jun 2011 12:16:54 +0300 | From | Avi Kivity <> | Subject | Re: [PATCH v2 19/22] KVM: MMU: lockless walking shadow page table |
| |
On 06/22/2011 05:35 PM, Xiao Guangrong wrote: > Use rcu to protect shadow pages table to be freed, so we can safely walk it, > it should run fastly and is needed by mmio page fault >
> static void kvm_mmu_commit_zap_page(struct kvm *kvm, > struct list_head *invalid_list) > { > @@ -1767,6 +1874,14 @@ static void kvm_mmu_commit_zap_page(struct kvm *kvm, > > kvm_flush_remote_tlbs(kvm); > > + if (atomic_read(&kvm->arch.reader_counter)) { > + kvm_mmu_isolate_pages(invalid_list); > + sp = list_first_entry(invalid_list, struct kvm_mmu_page, link); > + list_del_init(invalid_list); > + call_rcu(&sp->rcu, free_pages_rcu); > + return; > + } > +
I think we should do this unconditionally. The cost of ping-ponging the shared cache line containing reader_counter will increase with large smp counts. On the other hand, zap_page is very rare, so it can be a little slower. Also, less code paths = easier to understand.
-- error compiling committee.c: too many arguments to function
|