2019-05-23 20:13:08

by Dennis Zhou

Subject: [PATCH] blk-iolatency: only account submitted bios

As is, iolatency recognizes done_bio and cleanup as ending paths. If a
request is marked REQ_NOWAIT and fails to get a request, the bio is
cleaned up via rq_qos_cleanup() and ended in bio_wouldblock_error().
This results in underflowing the inflight counter. Fix this by only
accounting bios that were actually submitted.

Signed-off-by: Dennis Zhou <[email protected]>
Cc: Josef Bacik <[email protected]>
---
block/blk-iolatency.c | 4 ++++
1 file changed, 4 insertions(+)

diff --git a/block/blk-iolatency.c b/block/blk-iolatency.c
index 507212d75ee2..58bac44ba78a 100644
--- a/block/blk-iolatency.c
+++ b/block/blk-iolatency.c
@@ -599,6 +599,10 @@ static void blkcg_iolatency_done_bio(struct rq_qos *rqos, struct bio *bio)
if (!blkg || !bio_flagged(bio, BIO_TRACKED))
return;

+ /* We didn't actually submit this bio, don't account it. */
+ if (bio->bi_status == BLK_STS_AGAIN)
+ return;
+
iolat = blkg_to_lat(bio->bi_blkg);
if (!iolat)
return;
--
2.17.1

2019-06-15 16:52:49

by Dennis Zhou

Subject: Re: [PATCH] blk-iolatency: only account submitted bios

Hi Jens,

On Thu, May 23, 2019 at 04:10:18PM -0400, Dennis Zhou wrote:
> As is, iolatency recognizes done_bio and cleanup as ending paths. If a
> request is marked REQ_NOWAIT and fails to get a request, the bio is
> cleaned up via rq_qos_cleanup() and ended in bio_wouldblock_error().
> This results in underflowing the inflight counter. Fix this by only
> accounting bios that were actually submitted.
>
> Signed-off-by: Dennis Zhou <[email protected]>
> Cc: Josef Bacik <[email protected]>
> ---
> block/blk-iolatency.c | 4 ++++
> 1 file changed, 4 insertions(+)
>
> diff --git a/block/blk-iolatency.c b/block/blk-iolatency.c
> index 507212d75ee2..58bac44ba78a 100644
> --- a/block/blk-iolatency.c
> +++ b/block/blk-iolatency.c
> @@ -599,6 +599,10 @@ static void blkcg_iolatency_done_bio(struct rq_qos *rqos, struct bio *bio)
> if (!blkg || !bio_flagged(bio, BIO_TRACKED))
> return;
>
> + /* We didn't actually submit this bio, don't account it. */
> + if (bio->bi_status == BLK_STS_AGAIN)
> + return;
> +
> iolat = blkg_to_lat(bio->bi_blkg);
> if (!iolat)
> return;
> --
> 2.17.1
>

Can you please take a look at this?

Thanks,
Dennis

2019-06-20 09:31:24

by Jens Axboe

Subject: Re: [PATCH] blk-iolatency: only account submitted bios

On 5/23/19 2:10 PM, Dennis Zhou wrote:
> As is, iolatency recognizes done_bio and cleanup as ending paths. If a
> request is marked REQ_NOWAIT and fails to get a request, the bio is
> cleaned up via rq_qos_cleanup() and ended in bio_wouldblock_error().
> This results in underflowing the inflight counter. Fix this by only
> accounting bios that were actually submitted.

Looks good to me, applied.

--
Jens Axboe