Re: [PATCH v2 4/4] scsi-mq: Reduce suspend latency
From: Ming Lei <hidden>
Date: 2017-09-21 22:06:54
On Thu, Sep 21, 2017 at 02:22:55PM -0700, Bart Van Assche wrote:
quoted hunk ↗ jump to hunk
Avoid that it can take 200 ms too long to wait for ongoing requests to finish. Note: blk_mq_freeze_queue() uses a wait queue to wait for ongoing requests to finish. Signed-off-by: Bart Van Assche <redacted> Cc: Martin K. Petersen <martin.petersen@oracle.com> Cc: Ming Lei <redacted> Cc: Christoph Hellwig <hch@lst.de> Cc: Hannes Reinecke <hare@suse.com> Cc: Johannes Thumshirn <redacted> --- drivers/scsi/scsi_lib.c | 11 ++++++++--- 1 file changed, 8 insertions(+), 3 deletions(-)diff --git a/drivers/scsi/scsi_lib.c b/drivers/scsi/scsi_lib.c index e76fd6e89a81..34e5f0f95d01 100644 --- a/drivers/scsi/scsi_lib.c +++ b/drivers/scsi/scsi_lib.c@@ -2901,10 +2901,15 @@ scsi_device_quiesce(struct scsi_device *sdev) if (err) return err; - scsi_run_queue(q); - while (atomic_read(&sdev->device_busy)) { - msleep_interruptible(200); + if (q->mq_ops) { + blk_mq_freeze_queue(q); + blk_mq_unfreeze_queue(q);
As I commented in another patch, you don't check the 'preempt only' flag in normal I/O path, then from now on, any I/O can come.
+ } else {
scsi_run_queue(q);
+ while (atomic_read(&sdev->device_busy)) {
+ msleep_interruptible(200);
+ scsi_run_queue(q);
+ }Are you sure only blk-mq need to drain queue? We need to do that for block legacy too. -- Ming