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lib/generic-radix-tree.c: Make nodes more reasonably sized

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this code originally used the page allocator directly, but most code
shouldn't do that - PAGE_SIZE varies with architecture, and slab is
faster.

4k is also on the large side for typical usage, 512 bytes is a better
choice for typical usage that might be somewhat sparse.

Signed-off-by: Kent Overstreet <kent.overstreet@linux.dev>
This commit is contained in:
Kent Overstreet 2024-03-07 22:32:06 -05:00
parent d64547999c
commit 3a319a2476
2 changed files with 28 additions and 36 deletions
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29
include/linux/generic-radix-tree.h
View File

@ -5,7 +5,7 @@
* DOC: Generic radix trees/sparse arrays
*
* Very simple and minimalistic, supporting arbitrary size entries up to
* PAGE_SIZE.
* GENRADIX_NODE_SIZE.
*
* A genradix is defined with the type it will store, like so:
*
@ -45,12 +45,15 @@
struct genradix_root;
#define GENRADIX_NODE_SHIFT 9
#define GENRADIX_NODE_SIZE (1U << GENRADIX_NODE_SHIFT)
struct __genradix {
struct genradix_root *root;
};
/*
* NOTE: currently, sizeof(_type) must not be larger than PAGE_SIZE:
* NOTE: currently, sizeof(_type) must not be larger than GENRADIX_NODE_SIZE:
*/
#define __GENRADIX_INITIALIZER \
@ -101,14 +104,14 @@ void __genradix_free(struct __genradix *);
static inline size_t __idx_to_offset(size_t idx, size_t obj_size)
{
if (__builtin_constant_p(obj_size))
BUILD_BUG_ON(obj_size > PAGE_SIZE);
BUILD_BUG_ON(obj_size > GENRADIX_NODE_SIZE);
else
BUG_ON(obj_size > PAGE_SIZE);
BUG_ON(obj_size > GENRADIX_NODE_SIZE);
if (!is_power_of_2(obj_size)) {
size_t objs_per_page = PAGE_SIZE / obj_size;
size_t objs_per_page = GENRADIX_NODE_SIZE / obj_size;
return (idx / objs_per_page) * PAGE_SIZE +
return (idx / objs_per_page) * GENRADIX_NODE_SIZE +
(idx % objs_per_page) * obj_size;
} else {
return idx * obj_size;
@ -118,9 +121,9 @@ static inline size_t __idx_to_offset(size_t idx, size_t obj_size)
#define __genradix_cast(_radix) (typeof((_radix)->type[0]) *)
#define __genradix_obj_size(_radix) sizeof((_radix)->type[0])
#define __genradix_objs_per_page(_radix) \
(PAGE_SIZE / sizeof((_radix)->type[0]))
(GENRADIX_NODE_SIZE / sizeof((_radix)->type[0]))
#define __genradix_page_remainder(_radix) \
(PAGE_SIZE % sizeof((_radix)->type[0]))
(GENRADIX_NODE_SIZE % sizeof((_radix)->type[0]))
#define __genradix_idx_to_offset(_radix, _idx) \
__idx_to_offset(_idx, __genradix_obj_size(_radix))
@ -217,8 +220,8 @@ static inline void __genradix_iter_advance(struct genradix_iter *iter,
iter->offset += obj_size;
if (!is_power_of_2(obj_size) &&
(iter->offset & (PAGE_SIZE - 1)) + obj_size > PAGE_SIZE)
iter->offset = round_up(iter->offset, PAGE_SIZE);
(iter->offset & (GENRADIX_NODE_SIZE - 1)) + obj_size > GENRADIX_NODE_SIZE)
iter->offset = round_up(iter->offset, GENRADIX_NODE_SIZE);
iter->pos++;
}
@ -235,8 +238,8 @@ static inline void __genradix_iter_rewind(struct genradix_iter *iter,
return;
}
if ((iter->offset & (PAGE_SIZE - 1)) == 0)
iter->offset -= PAGE_SIZE % obj_size;
if ((iter->offset & (GENRADIX_NODE_SIZE - 1)) == 0)
iter->offset -= GENRADIX_NODE_SIZE % obj_size;
iter->offset -= obj_size;
iter->pos--;
@ -263,7 +266,7 @@ static inline void __genradix_iter_rewind(struct genradix_iter *iter,
genradix_for_each_from(_radix, _iter, _p, 0)
#define genradix_last_pos(_radix) \
(SIZE_MAX / PAGE_SIZE * __genradix_objs_per_page(_radix) - 1)
(SIZE_MAX / GENRADIX_NODE_SIZE * __genradix_objs_per_page(_radix) - 1)
/**
* genradix_for_each_reverse - iterate over entry in a genradix, reverse order

35
lib/generic-radix-tree.c
View File

@ -5,7 +5,7 @@
#include <linux/gfp.h>
#include <linux/kmemleak.h>
#define GENRADIX_ARY (PAGE_SIZE / sizeof(struct genradix_node *))
#define GENRADIX_ARY (GENRADIX_NODE_SIZE / sizeof(struct genradix_node *))
#define GENRADIX_ARY_SHIFT ilog2(GENRADIX_ARY)
struct genradix_node {
@ -14,13 +14,13 @@ struct genradix_node {
struct genradix_node *children[GENRADIX_ARY];
/* Leaf: */
u8 data[PAGE_SIZE];
u8 data[GENRADIX_NODE_SIZE];
};
};
static inline int genradix_depth_shift(unsigned depth)
{
return PAGE_SHIFT + GENRADIX_ARY_SHIFT * depth;
return GENRADIX_NODE_SHIFT + GENRADIX_ARY_SHIFT * depth;
}
/*
@ -33,7 +33,7 @@ static inline size_t genradix_depth_size(unsigned depth)
/* depth that's needed for a genradix that can address up to ULONG_MAX: */
#define GENRADIX_MAX_DEPTH \
DIV_ROUND_UP(BITS_PER_LONG - PAGE_SHIFT, GENRADIX_ARY_SHIFT)
DIV_ROUND_UP(BITS_PER_LONG - GENRADIX_NODE_SHIFT, GENRADIX_ARY_SHIFT)
#define GENRADIX_DEPTH_MASK \
((unsigned long) (roundup_pow_of_two(GENRADIX_MAX_DEPTH + 1) - 1))
@ -79,23 +79,12 @@ EXPORT_SYMBOL(__genradix_ptr);
static inline struct genradix_node *genradix_alloc_node(gfp_t gfp_mask)
{
struct genradix_node *node;
node = (struct genradix_node *)__get_free_page(gfp_mask|__GFP_ZERO);
/*
* We're using pages (not slab allocations) directly for kernel data
* structures, so we need to explicitly inform kmemleak of them in order
* to avoid false positive memory leak reports.
*/
kmemleak_alloc(node, PAGE_SIZE, 1, gfp_mask);
return node;
return kzalloc(GENRADIX_NODE_SIZE, gfp_mask);
}
static inline void genradix_free_node(struct genradix_node *node)
{
kmemleak_free(node);
free_page((unsigned long)node);
kfree(node);
}
/*
@ -200,7 +189,7 @@ restart:
i++;
iter->offset = round_down(iter->offset + objs_per_ptr,
objs_per_ptr);
iter->pos = (iter->offset >> PAGE_SHIFT) *
iter->pos = (iter->offset >> GENRADIX_NODE_SHIFT) *
objs_per_page;
if (i == GENRADIX_ARY)
goto restart;
@ -209,7 +198,7 @@ restart:
n = n->children[i];
}
return &n->data[iter->offset & (PAGE_SIZE - 1)];
return &n->data[iter->offset & (GENRADIX_NODE_SIZE - 1)];
}
EXPORT_SYMBOL(__genradix_iter_peek);
@ -235,7 +224,7 @@ restart:
if (ilog2(iter->offset) >= genradix_depth_shift(level)) {
iter->offset = genradix_depth_size(level);
iter->pos = (iter->offset >> PAGE_SHIFT) * objs_per_page;
iter->pos = (iter->offset >> GENRADIX_NODE_SHIFT) * objs_per_page;
iter->offset -= obj_size_plus_page_remainder;
iter->pos--;
@ -251,7 +240,7 @@ restart:
size_t objs_per_ptr = genradix_depth_size(level);
iter->offset = round_down(iter->offset, objs_per_ptr);
iter->pos = (iter->offset >> PAGE_SHIFT) * objs_per_page;
iter->pos = (iter->offset >> GENRADIX_NODE_SHIFT) * objs_per_page;
if (!iter->offset)
return NULL;
@ -267,7 +256,7 @@ restart:
n = n->children[i];
}
return &n->data[iter->offset & (PAGE_SIZE - 1)];
return &n->data[iter->offset & (GENRADIX_NODE_SIZE - 1)];
}
EXPORT_SYMBOL(__genradix_iter_peek_prev);
@ -289,7 +278,7 @@ int __genradix_prealloc(struct __genradix *radix, size_t size,
{
size_t offset;
for (offset = 0; offset < size; offset += PAGE_SIZE)
for (offset = 0; offset < size; offset += GENRADIX_NODE_SIZE)
if (!__genradix_ptr_alloc(radix, offset, gfp_mask))
return -ENOMEM;