vm_page: pass page to iter_free

[dougm]

Summary

Pass the to-be-freed page to vm_page_iter_free as a parameter, rather than computing it from the iterator parameter, to improve performance.

Sort declarations of page_iter functions in vm_page.h.

[alc]

sys/vm/vm_page.h

604–605

656

Insert before this declaration; move vm_page_launder and vm_page_lookup down to restore sorting.

[alc]

sys/vm/vm_page.c

1716–1717

This comment needs updating.

sys/vm/vm_page.h

655

This should be before _iter_init.

[dougm]

Pass the removed page to vm_page_iter_remove, and functions that use it. Update comments. Reorder declarations.

[alc]

Let's limit this change to vm_page_iter_free. It reduces the average cycles in _kmem_unback and vm_object_page_remove by 7% and 5.3%, respectively.

[dougm]

Remove changes to vm_page_iter_remove.