Messages in this thread | | | Subject | Re: [PATCH -mm v2 01/11] mm: track free size between VMAs in VMA rbtree | From | Peter Zijlstra <> | Date | Fri, 22 Jun 2012 12:02:59 +0200 |
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On Thu, 2012-06-21 at 17:57 -0400, Rik van Riel wrote: > +static unsigned long largest_free_gap(struct rb_node *node) > +{ > + struct vm_area_struct *vma, *prev, *left = NULL, *right = NULL; > + unsigned long largest = 0; > + > + if (node->rb_left) > + left = rb_to_vma(node->rb_left); > + if (node->rb_right) > + right = rb_to_vma(node->rb_right); > + > + /* Calculate the free gap size between us and the VMA to our left. */ > + vma = rb_to_vma(node); > + prev = vma->vm_prev; > + > + if (prev) > + largest = vma->vm_start - prev->vm_end; > + else > + largest = vma->vm_start; > + > + /* We propagate the largest of our own, or our children's free gaps. */ > + if (left) > + largest = max(largest, left->free_gap); > + if (right) > + largest = max(largest, right->free_gap); > + > + return largest; > +}
If you introduce helpers like:
static inline struct vm_area_struct *vma_of(struct rb_node *node) { return container_of(node, struct vm_area_struct, vm_rb); }
static inline unsigned long max_gap_of(struct rb_node *node) { return vma_of(node)->free_gap; }
static unsigned long gap_of(struct rb_node *node) { struct vm_area_struct *vma = vma_of(node);
if (!vma->vm_prev) return vma->vm_start;
return vma->vm_start - vma->vm_prev->vm_end; }
You can write your largest free gap as:
unsigned long largest_gap(struct rb_node *node) { unsigned long gap = gap_of(node);
if (node->rb_left) gap = max(gap, max_gap_of(node->rb_left)); if (node->rb_right) gap = max(gap, max_gap_of(node->rb_right));
return gap; }
And as shown, you can re-used those {max_,}gap_of() function in the lookup function in the next patch.
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