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Date: Tue, 25 Aug 2020 14:52:35 +0000 From: David Laight <David.Laight@...LAB.COM> To: "linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>, "'linux-sctp@...r.kernel.org'" <linux-sctp@...r.kernel.org>, Eric Biggers <ebiggers@...nel.org>, 'Marcelo Ricardo Leitner' <marcelo.leitner@...il.com>, 'Catalin Marinas' <catalin.marinas@....com>, "'kent.overstreet@...il.com'" <kent.overstreet@...il.com>, Andrew Morton <akpm@...ux-foundation.org>, "'Neil Horman'" <nhorman@...driver.com> Subject: [PATCH 07/13] lib/generic-radix-tree: Optimise __genradix_iter_peek() Use the the 'shift' rather than the 'level'. NB There are exactly zero users of this code. Signed-off-by: David Laight <david.laight@...lab.com> --- lib/generic-radix-tree.c | 24 ++++++++---------------- 1 file changed, 8 insertions(+), 16 deletions(-) diff --git a/lib/generic-radix-tree.c b/lib/generic-radix-tree.c index 219b43250a06..0df99ee428d8 100644 --- a/lib/generic-radix-tree.c +++ b/lib/generic-radix-tree.c @@ -22,14 +22,6 @@ static inline int genradix_depth_shift(unsigned depth) return PAGE_SHIFT + GENRADIX_ARY_SHIFT * depth; } -/* - * Returns size (of data, in bytes) that a tree of a given depth holds: - */ -static inline size_t genradix_depth_size(unsigned depth) -{ - return 1UL << genradix_depth_shift(depth); -} - /* * The 'depth' of the tree is held in the low bits of the 'root'. * Since all the buffers are allocated as pages lots of low bits are zero. @@ -209,7 +201,7 @@ void *__genradix_iter_peek(struct genradix_iter *iter, { struct genradix_root *r; struct genradix_node *n; - unsigned level, i; + unsigned int shift, level, i; restart: r = READ_ONCE(radix->root); if (!r) @@ -217,21 +209,21 @@ void *__genradix_iter_peek(struct genradix_iter *iter, n = genradix_root_to_node(r); level = genradix_root_to_depth(r); + shift = genradix_depth_shift(level); - if (iter->offset >> genradix_depth_shift(level)) + if (iter->offset >> shift) return NULL; - while (level) { - level--; + while (shift > GENRADIX_ARY_SHIFT) { + shift -= GENRADIX_ARY_SHIFT; - i = (iter->offset >> genradix_depth_shift(level)) & - (GENRADIX_ARY - 1); + i = (iter->offset >> shift) % GENRADIX_ARY; while (!n->children[i]) { i++; iter->offset = round_down(iter->offset + - genradix_depth_size(level), - genradix_depth_size(level)); + (1u << shift), + 1u << shift); iter->pos = (iter->offset >> PAGE_SHIFT) * objs_per_page; if (i == GENRADIX_ARY) -- 2.25.1 - Registered Address Lakeside, Bramley Road, Mount Farm, Milton Keynes, MK1 1PT, UK Registration No: 1397386 (Wales)
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