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| author |   Ming Lei <ming.lei@redhat.com> | 2019-10-25 14:58:55 +0800 |
|---|---|---|
| committer |   Martin K. Petersen <martin.petersen@oracle.com> | 2019-11-01 20:12:50 -0400 |
| commit | 6eb045e092efefafc6687409a6fa6d1dabf0fb69 (patch) | |
| tree | aeb333b78b8514f84daa88f6e431ea69ab51b22c /include/scsi | |
| parent | scsi: ufs: Use enum dev_cmd_type where appropriate (diff) | |
| download | linux-dev-6eb045e092efefafc6687409a6fa6d1dabf0fb69.tar.xz linux-dev-6eb045e092efefafc6687409a6fa6d1dabf0fb69.zip | |
scsi: core: avoid host-wide host_busy counter for scsi_mq
It isn't necessary to check the host depth in scsi_queue_rq() any more
since it has been respected by blk-mq before calling scsi_queue_rq() via
getting driver tag.
Lots of LUNs may attach to same host and per-host IOPS may reach millions,
so we should avoid expensive atomic operations on the host-wide counter in
the IO path.
This patch implements scsi_host_busy() via blk_mq_tagset_busy_iter() with
one scsi command state for reading the count of busy IOs for scsi_mq.
It is observed that IOPS is increased by 15% in IO test on scsi_debug (32
LUNs, 32 submit queues, 1024 can_queue, libaio/dio) in a dual-socket
system.
Cc: Jens Axboe <axboe@kernel.dk>
Cc: Ewan D. Milne <emilne@redhat.com>
Cc: Omar Sandoval <osandov@fb.com>,
Cc: "Martin K. Petersen" <martin.petersen@oracle.com>,
Cc: James Bottomley <james.bottomley@hansenpartnership.com>,
Cc: Christoph Hellwig <hch@lst.de>,
Cc: Kashyap Desai <kashyap.desai@broadcom.com>
Cc: Hannes Reinecke <hare@suse.de>
Cc: Laurence Oberman <loberman@redhat.com>
Cc: Bart Van Assche <bvanassche@acm.org>
Link: https://lore.kernel.org/r/20191025065855.6309-1-ming.lei@redhat.com
Signed-off-by: Ming Lei <ming.lei@redhat.com>
Reviewed-by: Jens Axboe <axboe@kernel.dk>
Reviewed-by: Bart Van Assche <bvanassche@acm.org>
Signed-off-by: Martin K. Petersen <martin.petersen@oracle.com>
Diffstat (limited to 'include/scsi')
| -rw-r--r-- | include/scsi/scsi_cmnd.h | 1 | ||||
| -rw-r--r-- | include/scsi/scsi_host.h | 3 |
2 files changed, 2 insertions, 2 deletions
diff --git a/include/scsi/scsi_cmnd.h b/include/scsi/scsi_cmnd.h index 91bd749a02f7..9c22e85902ec 100644 --- a/include/scsi/scsi_cmnd.h +++ b/include/scsi/scsi_cmnd.h @@ -63,6 +63,7 @@ struct scsi_pointer { /* for scmd->state */ #define SCMD_STATE_COMPLETE 0 +#define SCMD_STATE_INFLIGHT 1 struct scsi_cmnd { struct scsi_request req; diff --git a/include/scsi/scsi_host.h b/include/scsi/scsi_host.h index 2c3f0c58869b..fccdf84ec7e2 100644 --- a/include/scsi/scsi_host.h +++ b/include/scsi/scsi_host.h @@ -345,7 +345,7 @@ struct scsi_host_template { /* * This determines if we will use a non-interrupt driven * or an interrupt driven scheme. It is set to the maximum number - * of simultaneous commands a given host adapter will accept. + * of simultaneous commands a single hw queue in HBA will accept. */ int can_queue; @@ -554,7 +554,6 @@ struct Scsi_Host { /* Area to keep a shared tag map */ struct blk_mq_tag_set tag_set; - atomic_t host_busy; /* commands actually active on low-level */ atomic_t host_blocked; unsigned int host_failed; /* commands that failed. |