* [PATCH 07/13] lib/generic-radix-tree: Optimise __genradix_iter_peek()
@ 2020-08-25 14:52 David Laight
0 siblings, 0 replies; only message in thread
From: David Laight @ 2020-08-25 14:52 UTC (permalink / raw)
To: linux-kernel, 'linux-sctp@vger.kernel.org',
Eric Biggers, 'Marcelo Ricardo Leitner',
'Catalin Marinas', 'kent.overstreet@gmail.com',
Andrew Morton, 'Neil Horman'
Use the the 'shift' rather than the 'level'.
NB There are exactly zero users of this code.
Signed-off-by: David Laight <david.laight@aculab.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)
^ permalink raw reply related [flat|nested] only message in thread
only message in thread, other threads:[~2020-08-25 14:52 UTC | newest]
Thread overview: (only message) (download: mbox.gz / follow: Atom feed)
-- links below jump to the message on this page --
2020-08-25 14:52 [PATCH 07/13] lib/generic-radix-tree: Optimise __genradix_iter_peek() David Laight
This is a public inbox, see mirroring instructions
for how to clone and mirror all data and code used for this inbox;
as well as URLs for NNTP newsgroup(s).