return 0;
}
- sb->map = kzalloc_node(sb->map_nr * sizeof(*sb->map), flags, node);
+ sb->map = kcalloc_node(sb->map_nr, sizeof(*sb->map), flags, node);
if (!sb->map)
return -ENOMEM;
}
EXPORT_SYMBOL_GPL(sbitmap_bitmap_show);
-static unsigned int sbq_calc_wake_batch(unsigned int depth)
+static unsigned int sbq_calc_wake_batch(struct sbitmap_queue *sbq,
+ unsigned int depth)
{
unsigned int wake_batch;
+ unsigned int shallow_depth;
/*
* For each batch, we wake up one queue. We need to make sure that our
- * batch size is small enough that the full depth of the bitmap is
- * enough to wake up all of the queues.
+ * batch size is small enough that the full depth of the bitmap,
+ * potentially limited by a shallow depth, is enough to wake up all of
+ * the queues.
+ *
+ * Each full word of the bitmap has bits_per_word bits, and there might
+ * be a partial word. There are depth / bits_per_word full words and
+ * depth % bits_per_word bits left over. In bitwise arithmetic:
+ *
+ * bits_per_word = 1 << shift
+ * depth / bits_per_word = depth >> shift
+ * depth % bits_per_word = depth & ((1 << shift) - 1)
+ *
+ * Each word can be limited to sbq->min_shallow_depth bits.
*/
- wake_batch = SBQ_WAKE_BATCH;
- if (wake_batch > depth / SBQ_WAIT_QUEUES)
- wake_batch = max(1U, depth / SBQ_WAIT_QUEUES);
+ shallow_depth = min(1U << sbq->sb.shift, sbq->min_shallow_depth);
+ depth = ((depth >> sbq->sb.shift) * shallow_depth +
+ min(depth & ((1U << sbq->sb.shift) - 1), shallow_depth));
+ wake_batch = clamp_t(unsigned int, depth / SBQ_WAIT_QUEUES, 1,
+ SBQ_WAKE_BATCH);
return wake_batch;
}
*per_cpu_ptr(sbq->alloc_hint, i) = prandom_u32() % depth;
}
- sbq->wake_batch = sbq_calc_wake_batch(depth);
+ sbq->min_shallow_depth = UINT_MAX;
+ sbq->wake_batch = sbq_calc_wake_batch(sbq, depth);
atomic_set(&sbq->wake_index, 0);
sbq->ws = kzalloc_node(SBQ_WAIT_QUEUES * sizeof(*sbq->ws), flags, node);
}
EXPORT_SYMBOL_GPL(sbitmap_queue_init_node);
-void sbitmap_queue_resize(struct sbitmap_queue *sbq, unsigned int depth)
+static void sbitmap_queue_update_wake_batch(struct sbitmap_queue *sbq,
+ unsigned int depth)
{
- unsigned int wake_batch = sbq_calc_wake_batch(depth);
+ unsigned int wake_batch = sbq_calc_wake_batch(sbq, depth);
int i;
if (sbq->wake_batch != wake_batch) {
WRITE_ONCE(sbq->wake_batch, wake_batch);
/*
- * Pairs with the memory barrier in sbq_wake_up() to ensure that
- * the batch size is updated before the wait counts.
+ * Pairs with the memory barrier in sbitmap_queue_wake_up()
+ * to ensure that the batch size is updated before the wait
+ * counts.
*/
smp_mb__before_atomic();
for (i = 0; i < SBQ_WAIT_QUEUES; i++)
atomic_set(&sbq->ws[i].wait_cnt, 1);
}
+}
+
+void sbitmap_queue_resize(struct sbitmap_queue *sbq, unsigned int depth)
+{
+ sbitmap_queue_update_wake_batch(sbq, depth);
sbitmap_resize(&sbq->sb, depth);
}
EXPORT_SYMBOL_GPL(sbitmap_queue_resize);
unsigned int hint, depth;
int nr;
+ WARN_ON_ONCE(shallow_depth < sbq->min_shallow_depth);
+
hint = this_cpu_read(*sbq->alloc_hint);
depth = READ_ONCE(sbq->sb.depth);
if (unlikely(hint >= depth)) {
}
EXPORT_SYMBOL_GPL(__sbitmap_queue_get_shallow);
+void sbitmap_queue_min_shallow_depth(struct sbitmap_queue *sbq,
+ unsigned int min_shallow_depth)
+{
+ sbq->min_shallow_depth = min_shallow_depth;
+ sbitmap_queue_update_wake_batch(sbq, sbq->sb.depth);
+}
+EXPORT_SYMBOL_GPL(sbitmap_queue_min_shallow_depth);
+
static struct sbq_wait_state *sbq_wake_ptr(struct sbitmap_queue *sbq)
{
int i, wake_index;
return NULL;
}
-static void sbq_wake_up(struct sbitmap_queue *sbq)
+static bool __sbq_wake_up(struct sbitmap_queue *sbq)
{
struct sbq_wait_state *ws;
unsigned int wake_batch;
int wait_cnt;
- /*
- * Pairs with the memory barrier in set_current_state() to ensure the
- * proper ordering of clear_bit()/waitqueue_active() in the waker and
- * test_and_set_bit_lock()/prepare_to_wait()/finish_wait() in the
- * waiter. See the comment on waitqueue_active(). This is __after_atomic
- * because we just did clear_bit_unlock() in the caller.
- */
- smp_mb__after_atomic();
-
ws = sbq_wake_ptr(sbq);
if (!ws)
- return;
+ return false;
wait_cnt = atomic_dec_return(&ws->wait_cnt);
if (wait_cnt <= 0) {
+ int ret;
+
wake_batch = READ_ONCE(sbq->wake_batch);
+
/*
* Pairs with the memory barrier in sbitmap_queue_resize() to
* ensure that we see the batch size update before the wait
* count is reset.
*/
smp_mb__before_atomic();
+
/*
- * If there are concurrent callers to sbq_wake_up(), the last
- * one to decrement the wait count below zero will bump it back
- * up. If there is a concurrent resize, the count reset will
- * either cause the cmpxchg to fail or overwrite after the
- * cmpxchg.
+ * For concurrent callers of this, the one that failed the
+ * atomic_cmpxhcg() race should call this function again
+ * to wakeup a new batch on a different 'ws'.
*/
- atomic_cmpxchg(&ws->wait_cnt, wait_cnt, wait_cnt + wake_batch);
- sbq_index_atomic_inc(&sbq->wake_index);
- wake_up_nr(&ws->wait, wake_batch);
+ ret = atomic_cmpxchg(&ws->wait_cnt, wait_cnt, wake_batch);
+ if (ret == wait_cnt) {
+ sbq_index_atomic_inc(&sbq->wake_index);
+ wake_up_nr(&ws->wait, wake_batch);
+ return false;
+ }
+
+ return true;
}
+
+ return false;
+}
+
+void sbitmap_queue_wake_up(struct sbitmap_queue *sbq)
+{
+ while (__sbq_wake_up(sbq))
+ ;
}
+EXPORT_SYMBOL_GPL(sbitmap_queue_wake_up);
void sbitmap_queue_clear(struct sbitmap_queue *sbq, unsigned int nr,
unsigned int cpu)
{
sbitmap_clear_bit_unlock(&sbq->sb, nr);
- sbq_wake_up(sbq);
+ /*
+ * Pairs with the memory barrier in set_current_state() to ensure the
+ * proper ordering of clear_bit_unlock()/waitqueue_active() in the waker
+ * and test_and_set_bit_lock()/prepare_to_wait()/finish_wait() in the
+ * waiter. See the comment on waitqueue_active().
+ */
+ smp_mb__after_atomic();
+ sbitmap_queue_wake_up(sbq);
+
if (likely(!sbq->round_robin && nr < sbq->sb.depth))
*per_cpu_ptr(sbq->alloc_hint, cpu) = nr;
}
/*
* Pairs with the memory barrier in set_current_state() like in
- * sbq_wake_up().
+ * sbitmap_queue_wake_up().
*/
smp_mb();
wake_index = atomic_read(&sbq->wake_index);
seq_puts(m, "}\n");
seq_printf(m, "round_robin=%d\n", sbq->round_robin);
+ seq_printf(m, "min_shallow_depth=%u\n", sbq->min_shallow_depth);
}
EXPORT_SYMBOL_GPL(sbitmap_queue_show);
projects / linux-2.6-microblaze.git / blobdiff