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Commit 6f9e5c17 authored by Takuya Yoshikawa's avatar Takuya Yoshikawa Committed by Avi Kivity
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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: default avatarTakuya Yoshikawa <yoshikawa.takuya@oss.ntt.co.jp>
Signed-off-by: default avatarMarcelo Tosatti <mtosatti@redhat.com>
parent 515a0127

virt/kvm/kvm_main.c

+10 −3
Original line number Diff line number Diff line
@@ -449,7 +449,11 @@ static void kvm_destroy_dirty_bitmap(struct kvm_memory_slot *memslot) 
	if (!memslot->dirty_bitmap)

		return;



	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 @@ static int kvm_create_dirty_bitmap(struct kvm_memory_slot *memslot) 
{

	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;

}