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scsi: core: Make sure sdev->queue_depth is <= max(shost->can_queue, 1024)

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Limit SCSI device's queue depth to max(host->can_queue, 1024) in
scsi_change_queue_depth(). 1024 is big enough for saturating current fast
SCSI LUN(SSD or RAID volume on multiple SSDs). Also single hardware queue
depth is usually enough for saturating single LUN because per-core
performance is often considered in storage design.

This patch is needed for replacing sdev->device_busy with sbitmap which has
to be pre-allocated with reasonable max depth.

Link: https://lore.kernel.org/r/20210122023317.687987-13-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>
This commit is contained in:
Ming Lei 2021-01-22 10:33:16 +08:00 committed by Martin K. Petersen
parent 8278807abd
commit ca44532139
1 changed files with 11 additions and 0 deletions
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11
drivers/scsi/scsi.c
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@ -214,6 +214,15 @@ void scsi_finish_command(struct scsi_cmnd *cmd)
scsi_io_completion(cmd, good_bytes);
}
/*
* 1024 is big enough for saturating the fast scsi LUN now
*/
static int scsi_device_max_queue_depth(struct scsi_device *sdev)
{
return max_t(int, sdev->host->can_queue, 1024);
}
/**
* scsi_change_queue_depth - change a device's queue depth
* @sdev: SCSI Device in question
@ -223,6 +232,8 @@ void scsi_finish_command(struct scsi_cmnd *cmd)
*/
int scsi_change_queue_depth(struct scsi_device *sdev, int depth)
{
depth = min_t(int, depth, scsi_device_max_queue_depth(sdev));
if (depth > 0) {
sdev->queue_depth = depth;
wmb();