On 05/16/2013 08:45 PM, Paolo Bonzini wrote:
> Il 16/05/2013 14:17, Xiao Guangrong ha scritto:
>> Zap at lease 10 pages before releasing mmu-lock to reduce the overload
>> caused by requiring lock
>>
>> [ It improves kernel building 0.6% ~ 1% ]
>>
>> Signed-off-by: Xiao Guangrong <xiaoguangrong@xxxxxxxxxxxxxxxxxx>
>> ---
>> arch/x86/kvm/mmu.c | 11 ++++++++---
>> 1 files changed, 8 insertions(+), 3 deletions(-)
>>
>> diff --git a/arch/x86/kvm/mmu.c b/arch/x86/kvm/mmu.c
>> index e12f431..9c27fda 100644
>> --- a/arch/x86/kvm/mmu.c
>> +++ b/arch/x86/kvm/mmu.c
>> @@ -4216,10 +4216,12 @@ restart:
>> spin_unlock(&kvm->mmu_lock);
>> }
>>
>> +#define BATCH_ZAP_PAGES 10
>> static void zap_invalid_pages(struct kvm *kvm)
>> {
>> struct kvm_mmu_page *sp, *node;
>> LIST_HEAD(invalid_list);
>> + int batch = 0;
>>
>> restart:
>> list_for_each_entry_safe(sp, node, &kvm->arch.active_mmu_pages, link) {
>> @@ -4256,11 +4258,14 @@ restart:
>> * Need not flush tlb since we only zap the sp with invalid
>> * generation number.
>> */
>> - if (cond_resched_lock(&kvm->mmu_lock))
>> + if ((batch >= BATCH_ZAP_PAGES) &&
>> + cond_resched_lock(&kvm->mmu_lock)) {
>> + batch = 0;
>> goto restart;
>> + }
>>
>> - if (kvm_mmu_prepare_zap_page(kvm, sp, &invalid_list))
>> - goto restart;
>> + batch += kvm_mmu_prepare_zap_page(kvm, sp, &invalid_list);
>> + goto restart;
>
> Would this look again and again at the same page if
> kvm_mmu_prepare_zap_page returns 0?
We skip the invalid page (sp->role.invalid) before call
kvm_mmu_prepare_zap_page so that kvm_mmu_prepare_zap_page can not
meet the same page. ;)
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