diff options
| author | Ming Lei <ming.lei@redhat.com> | 2021-01-22 10:33:12 +0800 |
|---|---|---|
| committer | Martin K. Petersen <martin.petersen@oracle.com> | 2021-03-04 17:36:59 -0500 |
| commit | 2a5a24aa83382a88c43d18a901fab66e6ffe1199 (patch) | |
| tree | 85d9a1aa8d76bb25fe9fdc56f9a1b74f575ce485 /include/linux/blk-mq.h | |
| parent | d022d18c045fc2ccf92d0f14cf80f98eb0a8e119 (diff) | |
| download | lwn-2a5a24aa83382a88c43d18a901fab66e6ffe1199.tar.gz lwn-2a5a24aa83382a88c43d18a901fab66e6ffe1199.zip | |
scsi: blk-mq: Return budget token from .get_budget callback
SCSI uses a global atomic variable to track queue depth for each
LUN/request queue.
This doesn't scale well when there are lots of CPU cores and the disk is
very fast. It has been observed that IOPS is affected a lot by tracking
queue depth via sdev->device_busy in the I/O path.
Return budget token from .get_budget callback. The budget token can be
passed to driver so that we can replace the atomic variable with
sbitmap_queue and alleviate the scaling problems that way.
Link: https://lore.kernel.org/r/20210122023317.687987-9-ming.lei@redhat.com
Cc: Omar Sandoval <osandov@fb.com>
Cc: Kashyap Desai <kashyap.desai@broadcom.com>
Cc: Sumanesh Samanta <sumanesh.samanta@broadcom.com>
Cc: Ewan D. Milne <emilne@redhat.com>
Tested-by: Sumanesh Samanta <sumanesh.samanta@broadcom.com>
Reviewed-by: Hannes Reinecke <hare@suse.de>
Signed-off-by: Ming Lei <ming.lei@redhat.com>
Signed-off-by: Martin K. Petersen <martin.petersen@oracle.com>
Diffstat (limited to 'include/linux/blk-mq.h')
| -rw-r--r-- | include/linux/blk-mq.h | 4 |
1 files changed, 2 insertions, 2 deletions
diff --git a/include/linux/blk-mq.h b/include/linux/blk-mq.h index 5fae401f083d..3bd3ee651143 100644 --- a/include/linux/blk-mq.h +++ b/include/linux/blk-mq.h @@ -306,12 +306,12 @@ struct blk_mq_ops { * reserved budget. Also we have to handle failure case * of .get_budget for avoiding I/O deadlock. */ - bool (*get_budget)(struct request_queue *); + int (*get_budget)(struct request_queue *); /** * @put_budget: Release the reserved budget. */ - void (*put_budget)(struct request_queue *); + void (*put_budget)(struct request_queue *, int); /* * @set_rq_budget_toekn: store rq's budget token |