From: Bart Van Assche bvanassche@acm.org
[ Upstream commit d0b2b70eb12e9ffaf95e11b16b230a4e015a536c ]
With the current implementation of the UFS driver active_queues is 1 instead of 0 if all UFS request queues are idle. That causes hctx_may_queue() to divide the queue depth by 2 when queueing a request and hence reduces the usable queue depth.
The shared tag set code in the block layer keeps track of the number of active request queues. blk_mq_tag_busy() is called before a request is queued onto a hwq and blk_mq_tag_idle() is called some time after the hwq became idle. blk_mq_tag_idle() is called from inside blk_mq_timeout_work(). Hence, blk_mq_tag_idle() is only called if a timer is associated with each request that is submitted to a request queue that shares a tag set with another request queue.
Adds a blk_mq_start_request() call in ufshcd_exec_dev_cmd(). This doubles the queue depth on my test setup from 16 to 32.
In addition to increasing the usable queue depth, also fix the documentation of the 'timeout' parameter in the header above ufshcd_exec_dev_cmd().
Link: https://lore.kernel.org/r/20210513164912.5683-1-bvanassche@acm.org Fixes: 7252a3603015 ("scsi: ufs: Avoid busy-waiting by eliminating tag conflicts") Cc: Can Guo cang@codeaurora.org Cc: Alim Akhtar alim.akhtar@samsung.com Cc: Avri Altman avri.altman@wdc.com Cc: Stanley Chu stanley.chu@mediatek.com Cc: Bean Huo beanhuo@micron.com Cc: Adrian Hunter adrian.hunter@intel.com Reviewed-by: Can Guo cang@codeaurora.org Signed-off-by: Bart Van Assche bvanassche@acm.org Signed-off-by: Martin K. Petersen martin.petersen@oracle.com Signed-off-by: Sasha Levin sashal@kernel.org --- drivers/scsi/ufs/ufshcd.c | 5 ++++- 1 file changed, 4 insertions(+), 1 deletion(-)
diff --git a/drivers/scsi/ufs/ufshcd.c b/drivers/scsi/ufs/ufshcd.c index 0c71a159d08f..e1e510882ff4 100644 --- a/drivers/scsi/ufs/ufshcd.c +++ b/drivers/scsi/ufs/ufshcd.c @@ -2849,7 +2849,7 @@ static int ufshcd_wait_for_dev_cmd(struct ufs_hba *hba, * ufshcd_exec_dev_cmd - API for sending device management requests * @hba: UFS hba * @cmd_type: specifies the type (NOP, Query...) - * @timeout: time in seconds + * @timeout: timeout in milliseconds * * NOTE: Since there is only one available tag for device management commands, * it is expected you hold the hba->dev_cmd.lock mutex. @@ -2879,6 +2879,9 @@ static int ufshcd_exec_dev_cmd(struct ufs_hba *hba, } tag = req->tag; WARN_ON_ONCE(!ufshcd_valid_tag(hba, tag)); + /* Set the timeout such that the SCSI error handler is not activated. */ + req->timeout = msecs_to_jiffies(2 * timeout); + blk_mq_start_request(req);
init_completion(&wait); lrbp = &hba->lrb[tag];