d37371870c
Define vma->rb_subtree_gap as the largest gap between any vma in the subtree rooted at that vma, and their predecessor. Or, for a recursive definition, vma->rb_subtree_gap is the max of: - vma->vm_start - vma->vm_prev->vm_end - rb_subtree_gap fields of the vmas pointed by vma->rb.rb_left and vma->rb.rb_right This will allow get_unmapped_area_* to find a free area of the right size in O(log(N)) time, instead of potentially having to do a linear walk across all the VMAs. Also define mm->highest_vm_end as the vm_end field of the highest vma, so that we can easily check if the following gap is suitable. This does have the potential to make unmapping VMAs more expensive, especially for processes with very large numbers of VMAs, where the VMA rbtree can grow quite deep. Signed-off-by: Michel Lespinasse <walken@google.com> Reviewed-by: Rik van Riel <riel@redhat.com> Cc: Hugh Dickins <hughd@google.com> Cc: Russell King <linux@arm.linux.org.uk> Cc: Ralf Baechle <ralf@linux-mips.org> Cc: Paul Mundt <lethal@linux-sh.org> Cc: "David S. Miller" <davem@davemloft.net> Cc: Chris Metcalf <cmetcalf@tilera.com> Cc: Ingo Molnar <mingo@elte.hu> Cc: Thomas Gleixner <tglx@linutronix.de> Cc: "H. Peter Anvin" <hpa@zytor.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org> |
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