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radix-tree: add radix_tree_split_preload()

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Calculate how many nodes we need to allocate to split an old_order entry
into multiple entries, each of size new_order.  The test suite checks
that we allocated exactly the right number of nodes; neither too many
(checked by rtp->nr == 0), nor too few (checked by comparing
nr_allocated before and after the call to radix_tree_split()).

Link: http://lkml.kernel.org/r/1480369871-5271-60-git-send-email-mawilcox@linuxonhyperv.com
Signed-off-by: Matthew Wilcox <willy@linux.intel.com>
Tested-by: Kirill A. Shutemov <kirill.shutemov@linux.intel.com>
Cc: Konstantin Khlebnikov <koct9i@gmail.com>
Cc: Ross Zwisler <ross.zwisler@linux.intel.com>
Cc: Matthew Wilcox <mawilcox@microsoft.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
This commit is contained in:
Matthew Wilcox 2016-12-14 15:09:04 -08:00 committed by Linus Torvalds
parent e157b55594
commit 2791653a68
4 changed files with 69 additions and 3 deletions
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1
include/linux/radix-tree.h
View File

@ -345,6 +345,7 @@ static inline void radix_tree_preload_end(void)
preempt_enable();
}
int radix_tree_split_preload(unsigned old_order, unsigned new_order, gfp_t);
int radix_tree_split(struct radix_tree_root *, unsigned long index,
unsigned new_order);
int radix_tree_join(struct radix_tree_root *, unsigned long index,

24
lib/radix-tree.c
View File

@ -368,7 +368,7 @@ radix_tree_node_free(struct radix_tree_node *node)
* To make use of this facility, the radix tree must be initialised without
* __GFP_DIRECT_RECLAIM being passed to INIT_RADIX_TREE().
*/
static int __radix_tree_preload(gfp_t gfp_mask, int nr)
static int __radix_tree_preload(gfp_t gfp_mask, unsigned nr)
{
struct radix_tree_preload *rtp;
struct radix_tree_node *node;
@ -434,6 +434,28 @@ int radix_tree_maybe_preload(gfp_t gfp_mask)
}
EXPORT_SYMBOL(radix_tree_maybe_preload);
#ifdef CONFIG_RADIX_TREE_MULTIORDER
/*
* Preload with enough objects to ensure that we can split a single entry
* of order @old_order into many entries of size @new_order
*/
int radix_tree_split_preload(unsigned int old_order, unsigned int new_order,
gfp_t gfp_mask)
{
unsigned top = 1 << (old_order % RADIX_TREE_MAP_SHIFT);
unsigned layers = (old_order / RADIX_TREE_MAP_SHIFT) -
(new_order / RADIX_TREE_MAP_SHIFT);
unsigned nr = 0;
WARN_ON_ONCE(!gfpflags_allow_blocking(gfp_mask));
BUG_ON(new_order >= old_order);
while (layers--)
nr = nr * RADIX_TREE_MAP_SIZE + 1;
return __radix_tree_preload(gfp_mask, top * nr);
}
#endif
/*
* The same as function above, but preload number of nodes required to insert
* (1 << order) continuous naturally-aligned elements.

42
tools/testing/radix-tree/multiorder.c
View File

@ -389,35 +389,67 @@ static void multiorder_join(void)
}
}
static void check_mem(unsigned old_order, unsigned new_order, unsigned alloc)
{
struct radix_tree_preload *rtp = &radix_tree_preloads;
if (rtp->nr != 0)
printf("split(%u %u) remaining %u\n", old_order, new_order,
rtp->nr);
/*
* Can't check for equality here as some nodes may have been
* RCU-freed while we ran. But we should never finish with more
* nodes allocated since they should have all been preloaded.
*/
if (nr_allocated > alloc)
printf("split(%u %u) allocated %u %u\n", old_order, new_order,
alloc, nr_allocated);
}
static void __multiorder_split(int old_order, int new_order)
{
RADIX_TREE(tree, GFP_KERNEL);
RADIX_TREE(tree, GFP_ATOMIC);
void **slot;
struct radix_tree_iter iter;
struct radix_tree_node *node;
void *item;
unsigned alloc;
radix_tree_preload(GFP_KERNEL);
assert(item_insert_order(&tree, 0, old_order) == 0);
radix_tree_preload_end();
/* Wipe out the preloaded cache or it'll confuse check_mem() */
radix_tree_cpu_dead(0);
item_insert_order(&tree, 0, old_order);
radix_tree_tag_set(&tree, 0, 2);
radix_tree_split_preload(old_order, new_order, GFP_KERNEL);
alloc = nr_allocated;
radix_tree_split(&tree, 0, new_order);
check_mem(old_order, new_order, alloc);
radix_tree_for_each_slot(slot, &tree, &iter, 0) {
radix_tree_iter_replace(&tree, &iter, slot,
item_create(iter.index, new_order));
}
radix_tree_preload_end();
item_kill_tree(&tree);
radix_tree_preload(GFP_KERNEL);
__radix_tree_insert(&tree, 0, old_order, (void *)0x12);
radix_tree_preload_end();
item = __radix_tree_lookup(&tree, 0, &node, NULL);
assert(item == (void *)0x12);
assert(node->exceptional > 0);
radix_tree_split_preload(old_order, new_order, GFP_KERNEL);
radix_tree_split(&tree, 0, new_order);
radix_tree_for_each_slot(slot, &tree, &iter, 0) {
radix_tree_iter_replace(&tree, &iter, slot,
item_create(iter.index, new_order));
}
radix_tree_preload_end();
item = __radix_tree_lookup(&tree, 0, &node, NULL);
assert(item != (void *)0x12);
@ -425,16 +457,20 @@ static void __multiorder_split(int old_order, int new_order)
item_kill_tree(&tree);
radix_tree_preload(GFP_KERNEL);
__radix_tree_insert(&tree, 0, old_order, (void *)0x12);
radix_tree_preload_end();
item = __radix_tree_lookup(&tree, 0, &node, NULL);
assert(item == (void *)0x12);
assert(node->exceptional > 0);
radix_tree_split_preload(old_order, new_order, GFP_KERNEL);
radix_tree_split(&tree, 0, new_order);
radix_tree_for_each_slot(slot, &tree, &iter, 0) {
radix_tree_iter_replace(&tree, &iter, slot, (void *)0x16);
}
radix_tree_preload_end();
item = __radix_tree_lookup(&tree, 0, &node, NULL);
assert(item == (void *)0x16);
@ -471,4 +507,6 @@ void multiorder_checks(void)
multiorder_tagged_iteration();
multiorder_join();
multiorder_split();
radix_tree_cpu_dead(0);
}

5
tools/testing/radix-tree/test.h
View File

@ -52,3 +52,8 @@ int root_tag_get(struct radix_tree_root *root, unsigned int tag);
unsigned long node_maxindex(struct radix_tree_node *);
unsigned long shift_maxindex(unsigned int shift);
int radix_tree_cpu_dead(unsigned int cpu);
struct radix_tree_preload {
unsigned nr;
struct radix_tree_node *nodes;
};
extern struct radix_tree_preload radix_tree_preloads;