On 27/09/2022 16:03, Damien Le Moal wrote:
On 9/27/22 20:51, John Garry wrote:
On 26/09/2022 00:08, Damien Le Moal wrote:
The function __ata_change_queue_depth() uses the helper
ata_scsi_find_dev() to get the ata_device structure of a scsi device and
set that device maximum queue depth. However, when the ata device is
managed by libsas, ata_scsi_find_dev() returns NULL, turning
__ata_change_queue_depth() into a nop, which prevents the user from
setting the maximum queue depth of ATA devices used with libsas based
HBAs.
Fix this by renaming __ata_change_queue_depth() to
ata_change_queue_depth() and adding a pointer to the ata_device
structure of the target device as argument. This pointer is provided by
ata_scsi_change_queue_depth() using ata_scsi_find_dev() in the case of
a libata managed device and by sas_change_queue_depth() using
sas_to_ata_dev() in the case of a libsas managed ata device.
Signed-off-by: Damien Le Moal <damien.lemoal@xxxxxxxxxxxxxxxxxx>
Tested-by: John Garry <john.garry@xxxxxxxxxx>
However - a big however - I will note that this following behaviour is
strange for a SATA device for libsas:
root@(none)$ echo 33 > 0:0:2:0/device/queue_depth
root@(none)$ echo 33 > 0:0:2:0/device/queue_depth
sh: echo: write error: Invalid argument
root@(none)$
Weird. I am not getting any error (pm80xx driver). The qd gets capped at
32 as expected. Is it something that changes per libsas driver ?
That is with my pm8001 card.
What happens here is that the first store of 33 gets through to
ata_change_queue_depth() as it does not exceed the SAS shost can_queue,
which is >> 32, and then we cap this to 32 and store it in
sdev->queue_depth. And then the 2nd store of 33 also gets through, but
this following expression not evaluate true in ata_change_queue_depth():
queue_depth < 1 || queue_depth == sdev->queue_depth
So we don't return. However the following subsequent test does evaluate
true in ata_change_queue_depth():
if (sdev->queue_depth == queue_depth)
return -EINVAL;
And we error.
I also note that setting a value out of range is just rejected for a SAS
device, and not capped to the max range (like it is for SATA).
Not sure where that come from. A quick look does not reveal anything
obvious. Need to dig into that one.
AHCI rejects out of range values it as it exceeds the shost can_queue in
sdev_store_queue_depth().
Indeed:
echo 1 > /sys/block/sdk/device/queue_depth
echo 33 > /sys/block/sdk/device/queue_depth
Hmmmm... why no error message? is the printk silenced?
cat /sys/block/sdk/device/queue_depth
1
But for the libsas SATA device:
echo 1 > /sys/block/sdd/device/queue_depth
cat /sys/block/sdd/device/queue_depth
1
echo 33 > /sys/block/sdd/device/queue_depth
cat /sys/block/sdd/device/queue_depth
32
As one would expect... > Need to dig into that one.
thanks,
John
