On 11/23/21 9:41 AM, Christoph Hellwig wrote:
> On Tue, Nov 23, 2021 at 09:18:13AM -0700, Jens Axboe wrote:
>> This is essentially never used, yet it's about 1/3rd of the total
>> queue size. Allocate it when needed, and don't embed it in the queue.
>>
>> Signed-off-by: Jens Axboe <axboe@xxxxxxxxx>
>> ---
>> block/blk-mq.c | 20 ++++++++++++++++++--
>> block/blk-stat.c | 6 ------
>> block/blk-sysfs.c | 1 +
>> include/linux/blkdev.h | 9 +++++++--
>> 4 files changed, 26 insertions(+), 10 deletions(-)
>>
>> diff --git a/block/blk-mq.c b/block/blk-mq.c
>> index 20a6445f6a01..cb41c441aa8f 100644
>> --- a/block/blk-mq.c
>> +++ b/block/blk-mq.c
>> @@ -4577,9 +4577,25 @@ EXPORT_SYMBOL_GPL(blk_mq_update_nr_hw_queues);
>> /* Enable polling stats and return whether they were already enabled. */
>> static bool blk_poll_stats_enable(struct request_queue *q)
>> {
>> - if (test_bit(QUEUE_FLAG_POLL_STATS, &q->queue_flags) ||
>> - blk_queue_flag_test_and_set(QUEUE_FLAG_POLL_STATS, q))
>> + struct blk_rq_stat *poll_stat;
>> +
>> + if (test_bit(QUEUE_FLAG_POLL_STATS, &q->queue_flags))
>> return true;
>
> Can't we replace the checks for QUEUE_FLAG_POLL_STATS with checks for
> q->poll_stat now?
I think so:
diff --git a/block/blk-mq.c b/block/blk-mq.c
index f011fa3ebcc7..af4580bdf931 100644
--- a/block/blk-mq.c
+++ b/block/blk-mq.c
@@ -4593,7 +4593,7 @@ static bool blk_poll_stats_enable(struct request_queue *q)
{
struct blk_rq_stat *poll_stat;
- if (test_bit(QUEUE_FLAG_POLL_STATS, &q->queue_flags))
+ if (q->poll_stat)
return true;
poll_stat = kzalloc(BLK_MQ_POLL_STATS_BKTS * sizeof(*poll_stat),
@@ -4602,7 +4602,7 @@ static bool blk_poll_stats_enable(struct request_queue *q)
return false;
spin_lock_irq(&q->stats->lock);
- if (blk_queue_flag_test_and_set(QUEUE_FLAG_POLL_STATS, q)) {
+ if (q->poll_stat) {
spin_unlock_irq(&q->stats->lock);
kfree(poll_stat);
return true;
@@ -4620,8 +4620,7 @@ static void blk_mq_poll_stats_start(struct request_queue *q)
* We don't arm the callback if polling stats are not enabled or the
* callback is already active.
*/
- if (!test_bit(QUEUE_FLAG_POLL_STATS, &q->queue_flags) ||
- blk_stat_is_active(q->poll_cb))
+ if (!q->poll_stat || blk_stat_is_active(q->poll_cb))
return;
blk_stat_activate_msecs(q->poll_cb, 100);
diff --git a/block/blk-sysfs.c b/block/blk-sysfs.c
index e1b846ec58cb..c079be1c58a3 100644
--- a/block/blk-sysfs.c
+++ b/block/blk-sysfs.c
@@ -785,7 +785,7 @@ static void blk_release_queue(struct kobject *kobj)
might_sleep();
- if (test_bit(QUEUE_FLAG_POLL_STATS, &q->queue_flags))
+ if (q->poll_stat)
blk_stat_remove_callback(q, q->poll_cb);
blk_stat_free_callback(q->poll_cb);
diff --git a/include/linux/blkdev.h b/include/linux/blkdev.h
index 3d558cb397d5..20cf877d6627 100644
--- a/include/linux/blkdev.h
+++ b/include/linux/blkdev.h
@@ -414,7 +414,6 @@ struct request_queue {
#define QUEUE_FLAG_FUA 18 /* device supports FUA writes */
#define QUEUE_FLAG_DAX 19 /* device supports DAX */
#define QUEUE_FLAG_STATS 20 /* track IO start and completion times */
-#define QUEUE_FLAG_POLL_STATS 21 /* collecting stats for hybrid polling */
#define QUEUE_FLAG_REGISTERED 22 /* queue has been registered to a disk */
#define QUEUE_FLAG_QUIESCED 24 /* queue has been quiesced */
#define QUEUE_FLAG_PCI_P2PDMA 25 /* device supports PCI p2p requests */
--
Jens Axboe
