From 6eb045e092efefafc6687409a6fa6d1dabf0fb69 Mon Sep 17 00:00:00 2001 From: Ming Lei Date: Fri, 25 Oct 2019 14:58:55 +0800 Subject: 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 Cc: Ewan D. Milne Cc: Omar Sandoval , Cc: "Martin K. Petersen" , Cc: James Bottomley , Cc: Christoph Hellwig , Cc: Kashyap Desai Cc: Hannes Reinecke Cc: Laurence Oberman Cc: Bart Van Assche Link: https://lore.kernel.org/r/20191025065855.6309-1-ming.lei@redhat.com Signed-off-by: Ming Lei Reviewed-by: Jens Axboe Reviewed-by: Bart Van Assche Signed-off-by: Martin K. Petersen --- drivers/scsi/scsi.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) (limited to 'drivers/scsi/scsi.c') diff --git a/drivers/scsi/scsi.c b/drivers/scsi/scsi.c index 4f76841a7038..adfe8b3693d5 100644 --- a/drivers/scsi/scsi.c +++ b/drivers/scsi/scsi.c @@ -186,7 +186,7 @@ void scsi_finish_command(struct scsi_cmnd *cmd) struct scsi_driver *drv; unsigned int good_bytes; - scsi_device_unbusy(sdev); + scsi_device_unbusy(sdev, cmd); /* * Clear the flags that say that the device/target/host is no longer -- cgit v1.2.3