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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: Takuya Yoshikawa <yoshikawa.takuya@oss.ntt.co.jp>
Signed-off-by: Marcelo Tosatti <mtosatti@redhat.com>
This commit is contained in:
Takuya Yoshikawa 2010-11-01 14:36:09 +09:00 committed by Avi Kivity
parent 515a01279a
commit 6f9e5c1702
1 changed files with 10 additions and 3 deletions
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13
virt/kvm/kvm_main.c
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@ -449,7 +449,11 @@ static void kvm_destroy_dirty_bitmap(struct kvm_memory_slot *memslot)
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 @@ 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;
}