Commit f003a1f1 authored Aug 02, 2016 by Sebastian Ott Committed by Linus Torvalds Aug 02, 2016

lib/iommu-helper: skip to next segment

When a large enough area in the iommu bitmap is found but would span a
boundary we continue the search starting from the next bit position.
For large allocations this can lead to several useless invocations of
bitmap_find_next_zero_area() and iommu_is_span_boundary().

Continue the search from the start of the next segment (which is the
next bit position such that we'll not cross the same segment boundary
again).

Link: http://lkml.kernel.org/r/alpine.LFD.2.20.1606081910070.3211@schleppi


Signed-off-by: Sebastian Ott <sebott@linux.vnet.ibm.com>
Reviewed-by: Gerald Schaefer <gerald.schaefer@de.ibm.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

parent 4cad35a7

lib/iommu-helper.c

+1 −2

Original line number	Diff line number	Diff line
		@@ -29,8 +29,7 @@ again:
		index = bitmap_find_next_zero_area(map, size, start, nr, align_mask);
		if (index < size) {
		if (iommu_is_span_boundary(index, nr, shift, boundary_size)) {
		/* we could do more effectively */
		start = index + 1;
		start = ALIGN(shift + index, boundary_size) - shift;
		goto again;
		}
		bitmap_set(map, index, nr);

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