KVM: use kmalloc() for small dirty bitmaps
Currently we are using vmalloc() for all dirty bitmaps even if
they are small enough, say less than K bytes.
We use kmalloc() if dirty bitmap size is less than or equal to
PAGE_SIZE so that we can avoid vmalloc area usage for VGA.
This will also make the logging start/stop faster.
Signed-off-by: Takuya Yoshikawa <yoshikawa.takuya@oss.ntt.co.jp>
Signed-off-by: Marcelo Tosatti <mtosatti@redhat.com>
diff --git a/virt/kvm/kvm_main.c b/virt/kvm/kvm_main.c
index 27649fd..9ce1079 100644
--- a/virt/kvm/kvm_main.c
+++ b/virt/kvm/kvm_main.c
@@ -449,7 +449,11 @@
if (!memslot->dirty_bitmap)
return;
- vfree(memslot->dirty_bitmap_head);
+ if (2 * kvm_dirty_bitmap_bytes(memslot) > PAGE_SIZE)
+ vfree(memslot->dirty_bitmap_head);
+ else
+ kfree(memslot->dirty_bitmap_head);
+
memslot->dirty_bitmap = NULL;
memslot->dirty_bitmap_head = NULL;
}
@@ -547,11 +551,14 @@
{
unsigned long dirty_bytes = 2 * kvm_dirty_bitmap_bytes(memslot);
- memslot->dirty_bitmap = vmalloc(dirty_bytes);
+ if (dirty_bytes > PAGE_SIZE)
+ memslot->dirty_bitmap = vzalloc(dirty_bytes);
+ else
+ memslot->dirty_bitmap = kzalloc(dirty_bytes, GFP_KERNEL);
+
if (!memslot->dirty_bitmap)
return -ENOMEM;
- memset(memslot->dirty_bitmap, 0, dirty_bytes);
memslot->dirty_bitmap_head = memslot->dirty_bitmap;
return 0;
}