[RFC PATCH 3/5] libsas: dynamic queue depth

Dan Williams
2011-09-20T22:10:47Z

The queue-depth for libsas-attached devices initializes to 32 and can
only be increased manually via sysfs to a max of 64, while mpt2sas
attached devices initialize to 254 and dynamically float via the
midlayer ->change_queue_depth interface.

No performance regression was observed with this change on the isci
driver.

Cc: Christoph Hellwig <hch@lst.de>
Cc: Mark Salyzyn <msalyzyn@us.xyratex.com>
Cc: Xiangliang Yu <yuxiangl@marvell.com>
Cc: Jack Wang <jack_wang@usish.com>
Cc: Mark Salyzyn <msalyzyn@us.xyratex.com>
Cc: Luben Tuikov <ltuikov@yahoo.com>
Tested-by: Dave Jiang <dave.jiang@intel.com>
Signed-off-by: Dan Williams <dan.j.williams@intel.com>
---
drivers/scsi/libsas/sas_scsi_host.c | 39 ++++++++++++++++-------------------
1 files changed, 18 insertions(+), 21 deletions(-)

diff --git a/drivers/scsi/libsas/sas_scsi_host.c b/drivers/scsi/libsas/sas_scsi_host.c
index 4c6923c..fe08ef0 100644
--- a/drivers/scsi/libsas/sas_scsi_host.c
+++ b/drivers/scsi/libsas/sas_scsi_host.c
@@ -784,8 +784,7 @@ int sas_target_alloc(struct scsi_target *starget)
return 0;
}

-#define SAS_DEF_QD 32
-#define SAS_MAX_QD 64
+#define SAS_DEF_QD 256

int sas_slave_configure(struct scsi_device *scsi_dev)
{
@@ -828,31 +827,29 @@ void sas_slave_destroy(struct scsi_device *scsi_dev)
dev->sata_dev.ap->link.device[0].class = ATA_DEV_NONE;
}

-int sas_change_queue_depth(struct scsi_device *scsi_dev, int new_depth,
- int reason)
+int sas_change_queue_depth(struct scsi_device *sdev, int depth, int reason)
{
- struct domain_device *dev = sdev_to_domain_dev(scsi_dev);
- int res = min(new_depth, SAS_MAX_QD);
+ struct domain_device *dev = sdev_to_domain_dev(sdev);

if (dev_is_sata(dev))
- return __ata_change_queue_depth(dev->sata_dev.ap, scsi_dev,
- new_depth, reason);
-
- if (reason != SCSI_QDEPTH_DEFAULT)
+ return __ata_change_queue_depth(dev->sata_dev.ap, sdev, depth,
+ reason);
+
+ switch (reason) {
+ case SCSI_QDEPTH_DEFAULT:
+ case SCSI_QDEPTH_RAMP_UP:
+ if (!sdev->tagged_supported)
+ depth = 1;
+ scsi_adjust_queue_depth(sdev, scsi_get_tag_type(sdev), depth);
+ break;
+ case SCSI_QDEPTH_QFULL:
+ scsi_track_queue_full(sdev, depth);
+ break;
+ default:
return -EOPNOTSUPP;
-
- if (scsi_dev->tagged_supported)
- scsi_adjust_queue_depth(scsi_dev, scsi_get_tag_type(scsi_dev),
- res);
- else {
- sas_printk("device %llx LUN %x queue depth changed to 1\n",
- SAS_ADDR(dev->sas_addr),
- scsi_dev->lun);
- scsi_adjust_queue_depth(scsi_dev, 0, 1);
- res = 1;
}

- return res;
+ return depth;
}

int sas_change_queue_type(struct scsi_device *scsi_dev, int qt)