On Thu, Aug 27, 2009 at 01:56:31PM -0700, Vasu Dev wrote:
> On Thu, 2009-08-27 at 12:19 +0200, Christof Schmitt wrote:
> > On Wed, Aug 26, 2009 at 11:04:03AM -0700, Vasu Dev wrote:
> > > Increases queue_depth by one on fc_change_queue_depth call back
> > > with reason SCSI_QDEPTH_RAMP_UP.
> > >
> > > Signed-off-by: Vasu Dev <vasu.dev@xxxxxxxxx>
> > > ---
> > >
> > > drivers/scsi/libfc/fc_fcp.c | 5 +++++
> > > 1 files changed, 5 insertions(+), 0 deletions(-)
> > >
> > > diff --git a/drivers/scsi/libfc/fc_fcp.c b/drivers/scsi/libfc/fc_fcp.c
> > > index dda4162..92e8a1b 100644
> > > --- a/drivers/scsi/libfc/fc_fcp.c
> > > +++ b/drivers/scsi/libfc/fc_fcp.c
> > > @@ -2054,6 +2054,11 @@ int fc_change_queue_depth(struct scsi_device *sdev, int qdepth, int reason)
> > > case SCSI_QDEPTH_QFULL:
> > > scsi_track_queue_full(sdev, qdepth);
> > > break;
> > > + case SCSI_QDEPTH_RAMP_UP:
> > > + if (qdepth + 1 <= FC_FCP_DFLT_QUEUE_DEPTH)
> > > + scsi_adjust_queue_depth(sdev, scsi_get_tag_type(sdev),
> > > + qdepth + 1);
> > > + break;
> > > default:
> > > return -EOPNOTSUPP;
> > > }
> >
> > Overall the approach looks good to me.
> >
> > I am trying to find out how this applies to the zfcp driver. Is the
> > approach in fc_change_queue_depth a good example for a driver that
> > does not have to adjust internal resources when changing the queue
> > depth?
> >
>
> Yes, this is the case with libfc also since libfc also doesn't make any
> additional resource adjustments on this call back. However If needed
> then this call back can be used to make additional resource adjustments
> also as needed by lpfc driver in lpfc_change_queue_depth.
There are also no resource adjustments necessary inside the zfcp
driver, i attached a first patch to adapt the zfcp change_queue_depth
callback.
I reused the default_depth settings for checking the maximum queue
depth. But i am wondering if the check should happen differently.
Would it make more sense to have an adjustable maximum_depth attribute
for each SCSI device? Or would it be possible to always increase the
queue depth until the storage returns QUEUE_FULL again?
Christof
---
zfcp: Adapt change_queue_depth for queue full tracking
From: Christof Schmitt <christof.schmitt@xxxxxxxxxx>
Adapt the change_queue_depth callback in zfcp for the new reason
parameter. Simply pass each call back to the SCSI midlayer, there are
no resource adjustments necessary for zfcp.
Signed-off-by: Christof Schmitt <christof.schmitt@xxxxxxxxxx>
---
drivers/s390/scsi/zfcp_scsi.c | 20 ++++++++++++++++++--
1 file changed, 18 insertions(+), 2 deletions(-)
--- a/drivers/s390/scsi/zfcp_scsi.c 2009-08-28 12:00:12.000000000 +0200
+++ b/drivers/s390/scsi/zfcp_scsi.c 2009-08-28 12:01:27.000000000 +0200
@@ -28,9 +28,25 @@ char *zfcp_get_fcp_sns_info_ptr(struct f
return fcp_sns_info_ptr;
}
-static int zfcp_scsi_change_queue_depth(struct scsi_device *sdev, int depth)
+static int zfcp_scsi_change_queue_depth(struct scsi_device *sdev, int depth,
+ int reason)
{
- scsi_adjust_queue_depth(sdev, scsi_get_tag_type(sdev), depth);
+ switch (reason) {
+ case SCSI_QDEPTH_SYSFS_REQ:
+ scsi_adjust_queue_depth(sdev, scsi_get_tag_type(sdev), depth);
+ break;
+ case SCSI_QDEPTH_QFULL:
+ scsi_track_queue_full(sdev, depth);
+ break;
+ case SCSI_QDEPTH_RAMP_UP:
+ depth++;
+ if (depth <= default_depth)
+ scsi_adjust_queue_depth(sdev, scsi_get_tag_type(sdev),
+ depth);
+ break;
+ default:
+ return -EOPNOTSUPP;
+ }
return sdev->queue_depth;
}
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