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authorMing Lei <ming.lei@redhat.com>2019-10-25 08:58:55 +0200
committerMartin K. Petersen <martin.petersen@oracle.com>2019-11-02 01:12:50 +0100
commit6eb045e092efefafc6687409a6fa6d1dabf0fb69 (patch)
treeaeb333b78b8514f84daa88f6e431ea69ab51b22c /include/scsi
parentscsi: ufs: Use enum dev_cmd_type where appropriate (diff)
downloadlinux-6eb045e092efefafc6687409a6fa6d1dabf0fb69.tar.xz
linux-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.h1
-rw-r--r--include/scsi/scsi_host.h3
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.