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| author | Takuya Yoshikawa <yoshikawa_takuya_b1@lab.ntt.co.jp> | 2015-03-17 16:19:58 +0900 |
|---|---|---|
| committer | Marcelo Tosatti <mtosatti@redhat.com> | 2015-03-18 22:23:33 -0300 |
| commit | 58d2930f4ee335ab703d768cb0318331fc1bb62c (patch) | |
| tree | 8fa1d0537279336dac5e862b2bfe421ee7191a69 | |
| parent | faac2458518e20130664d77b657303758f1aaf5a (diff) | |
| download | linux-58d2930f4ee335ab703d768cb0318331fc1bb62c.tar.bz2 | |
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 <yoshikawa_takuya_b1@lab.ntt.co.jp>
Reviewed-by: Paolo Bonzini <pbonzini@redhat.com>
Signed-off-by: Marcelo Tosatti <mtosatti@redhat.com>
| -rw-r--r-- | virt/kvm/kvm_main.c | 8 |
1 files changed, 5 insertions, 3 deletions
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); |