scsi: core: Increase max device queue_depth to 4096

The maximum SCSI device queue depth of 1024 is not sufficient for RAID
volumes configured behind Broadcom RAID controllers.  For a 16-drive RAID
volume with a device queue depth limit of 1024, only 64 I/Os (1024/16) can
be issued per drive. That is not sufficient to saturate the device.

Link: https://lore.kernel.org/r/20220414103601.140687-1-sumit.saxena@broadcom.com
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>
Signed-off-by: Martin K. Petersen <martin.petersen@oracle.com>

diff --git a/drivers/scsi/scsi.c b/drivers/scsi/scsi.c
index 211aace..735b6c8 100644 (file)
--- 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);
 }
 
 /**