* [PATCH 10/13] lib/generic-radix-tree: Simplify offset calculation:
@ 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'
Since these are equivalent:
(idx / objs_per_page) * PAGE_SIZE + (idx % objs_per_page) * obj_size;
idx * obj_size + (idx / objs_per_page) * (PAGE_SIZE % obj_size);
Use the latter since it is slightly faster.
It also deosn't need an extra check for obj_size being a power of 2.
Signed-off-by: David Laight <david.laight@aculab.com>
---
include/linux/generic-radix-tree.h | 9 ++-------
1 file changed, 2 insertions(+), 7 deletions(-)
diff --git a/include/linux/generic-radix-tree.h b/include/linux/generic-radix-tree.h
index 53149bc1b92a..5fe1c4c5588d 100644
--- a/include/linux/generic-radix-tree.h
+++ b/include/linux/generic-radix-tree.h
@@ -100,14 +100,9 @@ void __genradix_free(struct __genradix *);
static inline size_t __idx_to_offset(size_t idx, size_t obj_size)
{
- if (!is_power_of_2(obj_size)) {
- size_t objs_per_page = PAGE_SIZE / obj_size;
+ size_t objs_per_page = PAGE_SIZE / obj_size;
- return (idx / objs_per_page) * PAGE_SIZE +
- (idx % objs_per_page) * obj_size;
- } else {
- return idx * obj_size;
- }
+ return idx * obj_size + (idx / objs_per_page) * (PAGE_SIZE % obj_size);
}
#define __genradix_cast(_radix) (typeof((_radix)->type[0]) *)
--
2.25.1
-
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