On Fri, May 01, 2020 at 03:01:14PM +0200, Hannes Reinecke wrote: > On 4/30/20 5:15 PM, Ming Lei wrote: > > On Thu, Apr 30, 2020 at 03:18:27PM +0200, Hannes Reinecke wrote: > > > When issuing a LUN reset we should be using a reserved command > > > to avoid overwriting the original command. > > > > > > Signed-off-by: Hannes Reinecke <hare@xxxxxxxx> > > > --- > > > drivers/scsi/csiostor/csio_init.c | 1 + > > > drivers/scsi/csiostor/csio_scsi.c | 48 +++++++++++++++++++++++---------------- > > > 2 files changed, 30 insertions(+), 19 deletions(-) > > > > > > diff --git a/drivers/scsi/csiostor/csio_init.c b/drivers/scsi/csiostor/csio_init.c > > > index 8dea7d53788a..5e1b0a24caf6 100644 > > > --- a/drivers/scsi/csiostor/csio_init.c > > > +++ b/drivers/scsi/csiostor/csio_init.c > > > @@ -622,6 +622,7 @@ csio_shost_init(struct csio_hw *hw, struct device *dev, > > > ln->dev_num = (shost->host_no << 16); > > > shost->can_queue = CSIO_MAX_QUEUE; > > > + shost->nr_reserved_cmds = 1; > > > > ->can_queue isn't increased by 1 given CSIO_MAX_QUEUE isn't changed, so > > setting shost->nr_reserved_cmds as 1 will cause io queue depth reduced by 1, > > that is supposed to not happen. > > > We cannot increase MAX_QUEUE arbitrarily as this is a compile time variable, > which seems to relate to a hardware setting. > > But I can see to update the reserved command functionality for allowing to > fetch commands from the normal I/O tag pool; in the case of LUN reset it > shouldn't make much of a difference as the all I/O is quiesced anyway. It isn't related with reset. This patch reduces active IO queue depth by 1 anytime no matter there is reset or not, and this way may cause performance regression. Thanks, Ming
