[PATCH] scsi: increase max device queue_depth to 4096

* [PATCH] scsi: increase max device queue_depth to 4096
@ 2022-04-14 10:36 Sumit Saxena
  2022-04-19  3:03 ` Martin K. Petersen
  2022-04-26  4:00 ` Martin K. Petersen
  0 siblings, 2 replies; 3+ messages in thread
From: Sumit Saxena @ 2022-04-14 10:36 UTC (permalink / raw)
  To: linux-scsi
  Cc: martin.petersen, sathya.prakash, kashyap.desai, Sumit Saxena,
	Ming Lei, Hannes Reinecke, Bart Van Assche, Sumanesh Samanta

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Maximum SCSI device queue depth limited to 1024 is not sufficient
for RAID volumes configured behind Broadcom RAID controllers.
For a 16 drives RAID volume with 1024 device QD, per drive
64 IOs(1024/16) can be issued which is not good enough to achieve
performance target.

Cc: Ming Lei <ming.lei@redhat.com>
Cc: Hannes Reinecke <hare@suse.de>
Cc: Bart Van Assche <bvanassche@acm.org>
Cc: Sumanesh Samanta <sumanesh.samanta@broadcom.com>
Signed-off-by: Sumit Saxena <sumit.saxena@broadcom.com>
---
 drivers/scsi/scsi.c | 4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

diff --git a/drivers/scsi/scsi.c b/drivers/scsi/scsi.c
index 211aace69c22..735b6c862b46 100644
--- a/drivers/scsi/scsi.c
+++ b/drivers/scsi/scsi.c
@@ -200,11 +200,11 @@ void scsi_finish_command(struct scsi_cmnd *cmd)
 
 
 /*
- * 1024 is big enough for saturating fast SCSI LUNs.
+ * 4096 is big enough for saturating fast SCSI LUNs.
  */
 int scsi_device_max_queue_depth(struct scsi_device *sdev)
 {
-	return min_t(int, sdev->host->can_queue, 1024);
+	return min_t(int, sdev->host->can_queue, 4096);
 }
 
 /**
-- 
2.27.0


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