From 58d2930f4ee335ab703d768cb0318331fc1bb62c Mon Sep 17 00:00:00 2001 From: Takuya Yoshikawa Date: Tue, 17 Mar 2015 16:19:58 +0900 Subject: KVM: Eliminate extra function calls in kvm_get_dirty_log_protect() When all bits in mask are not set, kvm_arch_mmu_enable_log_dirty_pt_masked() has nothing to do. But since it needs to be called from the generic code, it cannot be inlined, and a few function calls, two when PML is enabled, are wasted. Since it is common to see many pages remain clean, e.g. framebuffers can stay calm for a long time, it is worth eliminating this overhead. Signed-off-by: Takuya Yoshikawa Reviewed-by: Paolo Bonzini Signed-off-by: Marcelo Tosatti --- virt/kvm/kvm_main.c | 8 +++++--- 1 file changed, 5 insertions(+), 3 deletions(-) (limited to 'virt') diff --git a/virt/kvm/kvm_main.c b/virt/kvm/kvm_main.c index 49900fc21f89..ce7888a15128 100644 --- a/virt/kvm/kvm_main.c +++ b/virt/kvm/kvm_main.c @@ -1053,9 +1053,11 @@ int kvm_get_dirty_log_protect(struct kvm *kvm, mask = xchg(&dirty_bitmap[i], 0); dirty_bitmap_buffer[i] = mask; - offset = i * BITS_PER_LONG; - kvm_arch_mmu_enable_log_dirty_pt_masked(kvm, memslot, offset, - mask); + if (mask) { + offset = i * BITS_PER_LONG; + kvm_arch_mmu_enable_log_dirty_pt_masked(kvm, memslot, + offset, mask); + } } spin_unlock(&kvm->mmu_lock); -- cgit v1.2.3