From: Sebastian Ott <sebott@xxxxxxxxxxxxxxxxxx> Subject: 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@xxxxxxxxxxxxxxxxxx> Reviewed-by: Gerald Schaefer <gerald.schaefer@xxxxxxxxxx> Signed-off-by: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx> --- lib/iommu-helper.c | 3 +-- 1 file changed, 1 insertion(+), 2 deletions(-) diff -puN lib/iommu-helper.c~lib-iommu-helper-skip-to-next-segment lib/iommu-helper.c --- a/lib/iommu-helper.c~lib-iommu-helper-skip-to-next-segment +++ a/lib/iommu-helper.c @@ -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); _ -- To unsubscribe from this list: send the line "unsubscribe mm-commits" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
