diff mbox

[3/9] blk-mq: expose write hints through debugfs

Message ID 1498491480-16306-4-git-send-email-axboe@kernel.dk (mailing list archive)
State New, archived
Headers show

Commit Message

Jens Axboe June 26, 2017, 3:37 p.m. UTC 
Useful to verify that things are working the way they should.
Reading the file will return number of kb written with each
write hint. Writing the file will reset the statistics. No care
is taken to ensure that we don't race on updates.

Drivers will write to q->write_hints[] if they handle a given
write hint.

Reviewed-by: Andreas Dilger <adilger@dilger.ca>
Reviewed-by: Martin K. Petersen <martin.petersen@oracle.com>
Reviewed-by: Christoph Hellwig <hch@lst.de>
Signed-off-by: Jens Axboe <axboe@kernel.dk>
---
 block/blk-mq-debugfs.c | 24 ++++++++++++++++++++++++
 include/linux/blkdev.h |  3 +++
 2 files changed, 27 insertions(+)

Comments

Christoph Hellwig June 27, 2017, 3:17 p.m. UTC | #1 
On Mon, Jun 26, 2017 at 09:37:54AM -0600, Jens Axboe wrote:
> Useful to verify that things are working the way they should.
> Reading the file will return number of kb written with each
> write hint. Writing the file will reset the statistics. No care
> is taken to ensure that we don't race on updates.
> 
> Drivers will write to q->write_hints[] if they handle a given
> write hint.

How about moving the accounting itself to blk-mq as well?  Just noticed
that it's completely generic while looking over the nvme patch.
Jens Axboe June 27, 2017, 3:20 p.m. UTC | #2 
On 06/27/2017 09:17 AM, Christoph Hellwig wrote:
> On Mon, Jun 26, 2017 at 09:37:54AM -0600, Jens Axboe wrote:
>> Useful to verify that things are working the way they should.
>> Reading the file will return number of kb written with each
>> write hint. Writing the file will reset the statistics. No care
>> is taken to ensure that we don't race on updates.
>>
>> Drivers will write to q->write_hints[] if they handle a given
>> write hint.
> 
> How about moving the accounting itself to blk-mq as well?  Just noticed
> that it's completely generic while looking over the nvme patch.

I didn't want to do it, unless the driver is using streams.
diff mbox

Patch

diff --git a/block/blk-mq-debugfs.c b/block/blk-mq-debugfs.c
index 9edebbdce0bd..9ebc2945f991 100644
--- a/block/blk-mq-debugfs.c
+++ b/block/blk-mq-debugfs.c
@@ -135,6 +135,29 @@  static void print_stat(struct seq_file *m, struct blk_rq_stat *stat)
 	}
 }
 
+static int queue_write_hint_show(void *data, struct seq_file *m)
+{
+	struct request_queue *q = data;
+	int i;
+
+	for (i = 0; i < BLK_MAX_WRITE_HINTS; i++)
+		seq_printf(m, "hint%d: %llu\n", i, q->write_hints[i]);
+
+	return 0;
+}
+
+static ssize_t queue_write_hint_store(void *data, const char __user *buf,
+				      size_t count, loff_t *ppos)
+{
+	struct request_queue *q = data;
+	int i;
+
+	for (i = 0; i < BLK_MAX_WRITE_HINTS; i++)
+		q->write_hints[i] = 0;
+
+	return count;
+}
+
 static int queue_poll_stat_show(void *data, struct seq_file *m)
 {
 	struct request_queue *q = data;
@@ -730,6 +753,7 @@  static const struct blk_mq_debugfs_attr blk_mq_debugfs_queue_attrs[] = {
 	{"poll_stat", 0400, queue_poll_stat_show},
 	{"requeue_list", 0400, .seq_ops = &queue_requeue_list_seq_ops},
 	{"state", 0600, queue_state_show, queue_state_write},
+	{"write_hints", 0600, queue_write_hint_show, queue_write_hint_store},
 	{},
 };
 
diff --git a/include/linux/blkdev.h b/include/linux/blkdev.h
index bf2157141d53..596de77b9a0a 100644
--- a/include/linux/blkdev.h
+++ b/include/linux/blkdev.h
@@ -594,6 +594,9 @@  struct request_queue {
 	void			*rq_alloc_data;
 
 	struct work_struct	release_work;
+
+#define BLK_MAX_WRITE_HINTS	5
+	u64			write_hints[BLK_MAX_WRITE_HINTS];
 };
 
 #define QUEUE_FLAG_QUEUED	1	/* uses generic tag queueing */