2017-05-17 15:43 GMT+08:00 Paolo Bonzini <pbonz...@redhat.com>: >> Recently, I have tested the performance before migration and after migration >> failure >> using spec cpu2006 https://www.spec.org/cpu2006/, which is a standard >> performance >> evaluation tool. >> >> These are the steps: >> ====== >> (1) the version of kmod is 4.4.11(with slightly modified) and the version of >> qemu is 2.6.0 >> (with slightly modified), the kmod is applied with the following patch >> >> diff --git a/source/x86/x86.c b/source/x86/x86.c >> index 054a7d3..75a4bb3 100644 >> --- a/source/x86/x86.c >> +++ b/source/x86/x86.c >> @@ -8550,8 +8550,10 @@ void kvm_arch_commit_memory_region(struct kvm *kvm, >> */ >> if ((change != KVM_MR_DELETE) && >> (old->flags & KVM_MEM_LOG_DIRTY_PAGES) && >> - !(new->flags & KVM_MEM_LOG_DIRTY_PAGES)) >> - kvm_mmu_zap_collapsible_sptes(kvm, new); >> + !(new->flags & KVM_MEM_LOG_DIRTY_PAGES)) { >> + printk(KERN_ERR "zj make KVM_REQ_MMU_RELOAD request\n"); >> + kvm_make_all_cpus_request(kvm, KVM_REQ_MMU_RELOAD); >> + } >> >> /* >> * Set up write protection and/or dirty logging for the new slot. > > Try these modifications to the setup: > > 1) set up 1G hugetlbfs hugepages and use those for the guest's memory > > 2) test both without and with the above patch. >
In addition, we can compare /sys/kernel/debug/kvm/largepages w/ and w/o the patch. IIRC, /sys/kernel/debug/kvm/largepages will drop during live migration, it will keep a small value if live migration fails and w/o "lazy collapse small sptes into large sptes" codes, however, it will increase gradually if w/ the "lazy collapse small sptes into large sptes" codes. Regards, Wanpeng Li
