On Oct 21, 2009, at 12:49 AM, Christof Schmitt wrote:
On Tue, Oct 20, 2009 at 04:14:21PM -0700, Joe Eykholt wrote:
Vasu Dev wrote:
On Tue, 2009-10-20 at 20:54 +0200, Christof Schmitt wrote:
On Fri, Oct 16, 2009 at 04:08:24PM -0700, Vasu Dev wrote:
-v3
Moves max_queue_depth initialization after slave_configure is
called from after slave_alloc calling done. Also adjusted
max_queue_depth check to skip ramp up if current queue_depth
is >= max_queue_depth.
Signed-off-by: Vasu Dev <vasu.dev@xxxxxxxxx>
Looks good to me. I ran some tests on s390 and the queue depth
counter
increased until hitting the defined maximum.
Good.
@@ -779,6 +781,36 @@ static struct device_attribute
sdev_attr_queue_depth_rw =
sdev_store_queue_depth_rw);
static ssize_t
+sdev_show_queue_ramp_up_period(struct device *dev,
+ struct device_attribute *attr,
+ char *buf)
+{
+ struct scsi_device *sdev;
+ sdev = to_scsi_device(dev);
+ return snprintf(buf, 20, "%lu\n", sdev->queue_ramp_up_period);
+}
+
+static ssize_t
+sdev_store_queue_ramp_up_period(struct device *dev,
+ struct device_attribute *attr,
+ const char *buf, size_t count)
+{
+ struct scsi_device *sdev = to_scsi_device(dev);
+ unsigned long period;
+
+ if (strict_strtoul(buf, 10, &period))
+ return -EINVAL;
+
+ sdev->queue_ramp_up_period = period;
+ return period;
+}
[...]
+ unsigned long queue_ramp_up_period; /* ramp up period in
jiffies */
+#define SCSI_DEFAULT_RAMP_UP_PERIOD (120 * HZ)
Only a small inconvenience i guess: The sysfs attribute shows the
ramp-up-period in jiffies. On my system with HZ==100 the default is
12000 and i was wondering if this would be milliseconds or
something
related. If HZ changes, the unit of the ramp-up-period also
changes.
I would prefer having seconds or milliseconds in sysfs and only
using
jiffies internally.
Added timestamp comparison checks are straightforward without any
additional conversion on each check since added timestamps and
queue_ramp_up_period both are jiffies, so works better this way with
stored queue_ramp_up_period in jiffies.
I do see your point as well but jiffies unit is also common in
Linux.
However if you or some other feels strongly to change this to ms or
seconds unit then I could change store or show sysfs functions to
handle
this value in ms or second unit while storing it in jiffies in
queue_ramp_up_period.
Vasu
I agree with Christof on this, HZ may be 100 on some machines and
1000
on others. Management tools (if they ever adjust this) would like
standard units, so it should be in ms or seconds, and I prefer ms.
I would just change the sysfs functions as you say, and use jiffies
internally.
I would also vote for ms in sysfs and using jiffies internally. This
should be fairly easy using the functions jiffies_to_msecs and
msecs_to_jiffies.
Christof
I would vote for ms in sysfs since this will be more understandable
for user.
-- Giri
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