Hi, SCSI's per-LUN queue depth is usually for improving IO merge and balancing IO load among LUNs. blk-mq has provides fair driver tag allocation and managed IRQ balances interrupt load among queues, meantime IO merge doesn't play a big role for SSD, and NVMe doesn't apply per-namespace queue depth. This patchset tries to don't apply per-LUN queue depth for some high end HBA in case of SSD, then we can avoid the expensive atomic operation on sdev->device_busy. We do understand that this shared counter affects IOPS a lot. Thanks, Ming Ming Lei (6): scsi: mpt3sas: don't use .device_busy in device reset routine scsi: remove .for_blk_mq scsi: sd: register request queue after sd_revalidate_disk is done block: freeze queue for updating QUEUE_FLAG_NONROT scsi: core: don't limit per-LUN queue depth for SSD when HBA needs scsi: megaraid: set flag of no_device_queue_for_ssd block/blk-sysfs.c | 14 +++++++++- drivers/scsi/megaraid/megaraid_sas_base.c | 1 + drivers/scsi/mpt3sas/mpt3sas_scsih.c | 32 ++++++++++++++++++++- drivers/scsi/scsi_lib.c | 34 +++++++++++++++++++---- drivers/scsi/sd.c | 7 ++++- drivers/scsi/virtio_scsi.c | 1 - include/scsi/scsi_host.h | 4 +-- 7 files changed, 81 insertions(+), 12 deletions(-) Cc: Sathya Prakash <sathya.prakash@xxxxxxxxxxxx> Cc: Chaitra P B <chaitra.basappa@xxxxxxxxxxxx> Cc: Suganath Prabu Subramani <suganath-prabu.subramani@xxxxxxxxxxxx> Cc: Kashyap Desai <kashyap.desai@xxxxxxxxxxxx> Cc: Sumit Saxena <sumit.saxena@xxxxxxxxxxxx> Cc: Shivasharan S <shivasharan.srikanteshwara@xxxxxxxxxxxx> Cc: Ewan D. Milne <emilne@xxxxxxxxxx> Cc: Hannes Reinecke <hare@xxxxxxx> Cc: Bart Van Assche <bart.vanassche@xxxxxxx> -- 2.20.1
