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| author | Bart Van Assche <bvanassche@acm.org> | 2021-12-04 00:19:49 +0100 |
|---|---|---|
| committer | Martin K. Petersen <martin.petersen@oracle.com> | 2021-12-07 04:30:34 +0100 |
| commit | 8d077ede48c1532d791c027467d152ae137c54ab (patch) | |
| tree | 703844f9eb7251efddfe6f28e867ea519208aa0c /drivers/scsi/ufs/ufshcd.h | |
| parent | scsi: ufs: Stop using the clock scaling lock in the error handler (diff) | |
| download | linux-8d077ede48c1532d791c027467d152ae137c54ab.tar.xz linux-8d077ede48c1532d791c027467d152ae137c54ab.zip | |
scsi: ufs: Optimize the command queueing code
Remove the clock scaling lock from ufshcd_queuecommand() since it is a
performance bottleneck. Instead check the SCSI device budget bitmaps in the
code that waits for ongoing ufshcd_queuecommand() calls. A bit is set in
sdev->budget_map just before scsi_queue_rq() is called and a bit is cleared
from that bitmap if scsi_queue_rq() does not submit the request or after
the request has finished. See also the blk_mq_{get,put}_dispatch_budget()
calls in the block layer.
There is no risk for a livelock since the block layer delays queue reruns
if queueing a request fails because the SCSI host has been blocked.
Link: https://lore.kernel.org/r/20211203231950.193369-17-bvanassche@acm.org
Cc: Asutosh Das (asd) <asutoshd@codeaurora.org>
Reviewed-by: Asutosh Das <asutoshd@codeaurora.org>
Signed-off-by: Bart Van Assche <bvanassche@acm.org>
Signed-off-by: Martin K. Petersen <martin.petersen@oracle.com>
Diffstat (limited to 'drivers/scsi/ufs/ufshcd.h')
| -rw-r--r-- | drivers/scsi/ufs/ufshcd.h | 1 |
1 files changed, 1 insertions, 0 deletions
diff --git a/drivers/scsi/ufs/ufshcd.h b/drivers/scsi/ufs/ufshcd.h index 8e942762e668..88c20f3608c2 100644 --- a/drivers/scsi/ufs/ufshcd.h +++ b/drivers/scsi/ufs/ufshcd.h @@ -778,6 +778,7 @@ struct ufs_hba_monitor { * @clk_list_head: UFS host controller clocks list node head * @pwr_info: holds current power mode * @max_pwr_info: keeps the device max valid pwm + * @clk_scaling_lock: used to serialize device commands and clock scaling * @desc_size: descriptor sizes reported by device * @urgent_bkops_lvl: keeps track of urgent bkops level for device * @is_urgent_bkops_lvl_checked: keeps track if the urgent bkops level for |