sbitmap: push per-cpu last_tag into sbitmap_queue
Allocating your own per-cpu allocation hint separately makes for an
awkward API. Instead, allocate the per-cpu hint as part of the struct
sbitmap_queue. There's no point for a struct sbitmap_queue without the
cache, but you can still use a bare struct sbitmap.
Signed-off-by: Omar Sandoval <osandov@fb.com>
Signed-off-by: Jens Axboe <axboe@fb.com>
diff --git a/include/linux/sbitmap.h b/include/linux/sbitmap.h
index 1a3b836..6745545 100644
--- a/include/linux/sbitmap.h
+++ b/include/linux/sbitmap.h
@@ -99,6 +99,14 @@
*/
struct sbitmap sb;
+ /*
+ * @alloc_hint: Cache of last successfully allocated or freed bit.
+ *
+ * This is per-cpu, which allows multiple users to stick to different
+ * cachelines until the map is exhausted.
+ */
+ unsigned int __percpu *alloc_hint;
+
/**
* @wake_batch: Number of bits which must be freed before we wake up any
* waiters.
@@ -267,6 +275,7 @@
static inline void sbitmap_queue_free(struct sbitmap_queue *sbq)
{
kfree(sbq->ws);
+ free_percpu(sbq->alloc_hint);
sbitmap_free(&sbq->sb);
}
@@ -282,12 +291,46 @@
void sbitmap_queue_resize(struct sbitmap_queue *sbq, unsigned int depth);
/**
+ * __sbitmap_queue_get() - Try to allocate a free bit from a &struct
+ * sbitmap_queue with preemption already disabled.
+ * @sbq: Bitmap queue to allocate from.
+ * @round_robin: See sbitmap_get().
+ *
+ * Return: Non-negative allocated bit number if successful, -1 otherwise.
+ */
+int __sbitmap_queue_get(struct sbitmap_queue *sbq, bool round_robin);
+
+/**
+ * sbitmap_queue_get() - Try to allocate a free bit from a &struct
+ * sbitmap_queue.
+ * @sbq: Bitmap queue to allocate from.
+ * @round_robin: See sbitmap_get().
+ * @cpu: Output parameter; will contain the CPU we ran on (e.g., to be passed to
+ * sbitmap_queue_clear()).
+ *
+ * Return: Non-negative allocated bit number if successful, -1 otherwise.
+ */
+static inline int sbitmap_queue_get(struct sbitmap_queue *sbq, bool round_robin,
+ unsigned int *cpu)
+{
+ int nr;
+
+ *cpu = get_cpu();
+ nr = __sbitmap_queue_get(sbq, round_robin);
+ put_cpu();
+ return nr;
+}
+
+/**
* sbitmap_queue_clear() - Free an allocated bit and wake up waiters on a
* &struct sbitmap_queue.
* @sbq: Bitmap to free from.
* @nr: Bit number to free.
+ * @round_robin: See sbitmap_get().
+ * @cpu: CPU the bit was allocated on.
*/
-void sbitmap_queue_clear(struct sbitmap_queue *sbq, unsigned int nr);
+void sbitmap_queue_clear(struct sbitmap_queue *sbq, unsigned int nr,
+ bool round_robin, unsigned int cpu);
static inline int sbq_index_inc(int index)
{