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Message-Id: <1346761229-27228-1-git-send-email-benjamin.gaignard@linaro.org>
Date: Tue, 4 Sep 2012 14:20:29 +0200
From: benjamin.gaignard@...aro.org
To: linux-kernel@...r.kernel.org, akpm@...ux-foundation.org,
ying.huang@...el.com, imre.deak@...ia.com
Cc: Benjamin Gaignard <benjamin.gaignard@...ricsson.com>
Subject: [PATCH] genalloc: add best fit algorithm
From: Benjamin Gaignard <benjamin.gaignard@...ricsson.com>
Allow genalloc to use another algorithm than first-fit one.
Add a best-fit algorithm.
Change-Id: Ie783c9f9687c08195b4cb1914856cd6aca50c611
Signed-off-by: Benjamin Gaignard <benjamin.gaignard@...ricsson.com>
---
include/linux/genalloc.h | 28 +++++++++++++++
lib/genalloc.c | 85 +++++++++++++++++++++++++++++++++++++++++++---
2 files changed, 109 insertions(+), 4 deletions(-)
diff --git a/include/linux/genalloc.h b/include/linux/genalloc.h
index 5e98eeb..b974998 100644
--- a/include/linux/genalloc.h
+++ b/include/linux/genalloc.h
@@ -36,6 +36,13 @@ struct gen_pool {
spinlock_t lock;
struct list_head chunks; /* list of chunks in this pool */
int min_alloc_order; /* minimum allocation order */
+
+ unsigned long (*algo)(void *priv,
+ unsigned long *map,
+ unsigned long size,
+ unsigned long start,
+ unsigned int nr);
+ void *priv_data;
};
/*
@@ -78,4 +85,25 @@ extern void gen_pool_for_each_chunk(struct gen_pool *,
void (*)(struct gen_pool *, struct gen_pool_chunk *, void *), void *);
extern size_t gen_pool_avail(struct gen_pool *);
extern size_t gen_pool_size(struct gen_pool *);
+
+extern void gen_pool_set_algo(struct gen_pool *pool, void *priv,
+ unsigned long (*algo)(
+ void *priv,
+ unsigned long *map,
+ unsigned long size,
+ unsigned long start,
+ unsigned int nr));
+
+extern unsigned long gen_pool_first_fit(void *priv,
+ unsigned long *map,
+ unsigned long size,
+ unsigned long start,
+ unsigned int nr);
+
+extern unsigned long gen_pool_best_fit(void *priv,
+ unsigned long *map,
+ unsigned long size,
+ unsigned long start,
+ unsigned int nr);
+
#endif /* __GENALLOC_H__ */
diff --git a/lib/genalloc.c b/lib/genalloc.c
index 6bc04aa..fdc4e72 100644
--- a/lib/genalloc.c
+++ b/lib/genalloc.c
@@ -152,6 +152,8 @@ struct gen_pool *gen_pool_create(int min_alloc_order, int nid)
spin_lock_init(&pool->lock);
INIT_LIST_HEAD(&pool->chunks);
pool->min_alloc_order = min_alloc_order;
+ pool->algo = gen_pool_first_fit;
+ pool->priv_data = NULL;
}
return pool;
}
@@ -255,8 +257,9 @@ EXPORT_SYMBOL(gen_pool_destroy);
* @size: number of bytes to allocate from the pool
*
* Allocate the requested number of bytes from the specified pool.
- * Uses a first-fit algorithm. Can not be used in NMI handler on
- * architectures without NMI-safe cmpxchg implementation.
+ * Uses the pool allocation function (first-fit algorithm by default).
+ * Can not be used in NMI handler on architectures without
+ * NMI-safe cmpxchg implementation.
*/
unsigned long gen_pool_alloc(struct gen_pool *pool, size_t size)
{
@@ -280,8 +283,8 @@ unsigned long gen_pool_alloc(struct gen_pool *pool, size_t size)
end_bit = (chunk->end_addr - chunk->start_addr) >> order;
retry:
- start_bit = bitmap_find_next_zero_area(chunk->bits, end_bit,
- start_bit, nbits, 0);
+ start_bit = pool->algo(pool->priv_data, chunk->bits, end_bit,
+ start_bit, nbits);
if (start_bit >= end_bit)
continue;
remain = bitmap_set_ll(chunk->bits, start_bit, nbits);
@@ -400,3 +403,77 @@ size_t gen_pool_size(struct gen_pool *pool)
return size;
}
EXPORT_SYMBOL_GPL(gen_pool_size);
+
+/**
+ * gen_pool_set_algo - set the allocation algorithm
+ * @pool: pool to change allocation algorithm
+ * @priv: private data to be pass to algorithm function
+ * @algo: custom algorithm function
+ */
+void gen_pool_set_algo(struct gen_pool *pool, void *priv,
+ unsigned long (*algo)(void *priv, unsigned long *map,
+ unsigned long size, unsigned long start, unsigned int nr))
+{
+ rcu_read_lock();
+
+ pool->algo = algo;
+ if (!pool->algo)
+ pool->algo = gen_pool_first_fit;
+
+ pool->priv_data = priv;
+
+ rcu_read_unlock();
+}
+EXPORT_SYMBOL(gen_pool_set_algo);
+
+/**
+ * gen_pool_first_fit - find the first available region
+ * of memory macthing the size requirement (no alignment constraint)
+ * @priv: private data - unused
+ * @map: The address to base the search on
+ * @size: The bitmap size in bits
+ * @start: The bitnumber to start searching at
+ * @nr: The number of zeroed bits we're looking for
+ */
+unsigned long gen_pool_first_fit(void *priv, unsigned long *map,
+ unsigned long size, unsigned long start, unsigned int nr)
+{
+ return bitmap_find_next_zero_area(map, size, start, nr, 0);
+}
+EXPORT_SYMBOL(gen_pool_first_fit);
+
+/**
+ * gen_pool_best_fit - find the best fiting region of memory
+ * @priv: private data - unused
+ * @map: The address to base the search on
+ * @size: The bitmap size in bits
+ * @start: The bitnumber to start searching at
+ * @nr: The number of zeroed bits we're looking for
+ *
+ * iterate over the bitmap to find the smaller region where we
+ * can allocate the memory.
+ */
+unsigned long gen_pool_best_fit(void *priv, unsigned long *map,
+ unsigned long size, unsigned long start, unsigned int nr)
+{
+ unsigned long start_bit = size;
+ unsigned long len = size + 1;
+ unsigned long index;
+
+ index = bitmap_find_next_zero_area(map, size, start, nr, 0);
+
+ while (index < size) {
+ int next_bit = find_next_bit(map, size, index + nr);
+ if ((next_bit - index) < len) {
+ len = next_bit - index;
+ start_bit = index;
+ if (len == nr)
+ return start_bit;
+ }
+ index = bitmap_find_next_zero_area(map, size,
+ next_bit + 1, nr, 0);
+ }
+
+ return start_bit;
+}
+EXPORT_SYMBOL(gen_pool_best_fit);
--
1.7.10
--
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