Patchwork [1/2] don't wait on disk to start on resume

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Submitter Aaron Lu
Date Feb. 2, 2013, 10:45 a.m.
Message ID <510CEE46.80308@intel.com>
Download mbox | patch
Permalink /patch/217649/
State Not Applicable
Delegated to: David Miller
Headers show

Comments

Aaron Lu - Feb. 2, 2013, 10:45 a.m.
On 02/01/2013 11:28 PM, Alan Stern wrote:
> On Fri, 1 Feb 2013, Aaron Lu wrote:
> 
>> Hi Derek,
>>
>> On 12/21/2012 12:35 PM, Derek Basehore wrote:
>>> We no longer wait for the disk to spin up in sd_resume. It now enters the
>>> request to spinup the disk into the elevator and returns.
>>>
>>> A function is scheduled under the scsi_sd_probe_domain to wait for the command
>>> to spinup the disk to complete. This function then checks for errors and cleans
>>> up after the sd resume function.
>>>
>>> This allows system resume to complete much faster on systems with an HDD since
>>> spinning up the disk is a significant portion of resume time.
>>
>> An alternative way of possibly solving this problem from PM's point of
>> view might be:
>> 1 Set both ata port and scsi device's runtime status to RPM_SUSPENDED
>>   in their system suspend callback;
>> 2 On resume, do nothing in their system resume callback;
>> 3 With request based runtime PM introduced here:
>>   http://thread.gmane.org/gmane.linux.power-management.general/30405
>>   When a request comes for the HDD after system resume, both the ata
>>   port and the scsi device will be runtime resumed, which involves
>>   re-initialize the ata link(in ata port's runtime resume callback) and
>>   spin up the HDD(in sd's runtime resume callback).
>>
>> To make HDD un-affetcted by runtime PM during normal use, a large enough
>> autosuspend_delay can be set for it.
>>
>> Just my 2 cents, I've not verified or tried in any way yet :-)
> 
> It's a good idea.  The problem is that it won't work if CONFIG_PM_SLEEP
> is enabled but CONFIG_PM_RUNTIME isn't.

Right, what a pity... thanks for the hint.

But the code is really simple if we ignore this problem(with some proper
modifications to scsi bus PM callbacks, see the delayed_resume branch if
you are interested), so I'm tempted to post it here :-)

 drivers/ata/libata-core.c | 22 +++++++++++-----------
 drivers/scsi/scsi_pm.c    | 14 +++++++++++---
 2 files changed, 22 insertions(+), 14 deletions(-)
Alan Stern - Feb. 2, 2013, 3:09 p.m.
On Sat, 2 Feb 2013, Aaron Lu wrote:

> >> An alternative way of possibly solving this problem from PM's point of
> >> view might be:
> >> 1 Set both ata port and scsi device's runtime status to RPM_SUSPENDED
> >>   in their system suspend callback;

By the way, what reason is there for doing this to the ATA port?  Does 
the port take a long time to resume, in the same way that a disk can 
take a few seconds to spin back up?

> >> 2 On resume, do nothing in their system resume callback;
> >> 3 With request based runtime PM introduced here:
> >>   http://thread.gmane.org/gmane.linux.power-management.general/30405
> >>   When a request comes for the HDD after system resume, both the ata
> >>   port and the scsi device will be runtime resumed, which involves
> >>   re-initialize the ata link(in ata port's runtime resume callback) and
> >>   spin up the HDD(in sd's runtime resume callback).
> >>
> >> To make HDD un-affetcted by runtime PM during normal use, a large enough
> >> autosuspend_delay can be set for it.
> >>
> >> Just my 2 cents, I've not verified or tried in any way yet :-)
> > 
> > It's a good idea.  The problem is that it won't work if CONFIG_PM_SLEEP
> > is enabled but CONFIG_PM_RUNTIME isn't.
> 
> Right, what a pity... thanks for the hint.
> 
> But the code is really simple if we ignore this problem(with some proper
> modifications to scsi bus PM callbacks, see the delayed_resume branch if
> you are interested), so I'm tempted to post it here :-)
> 
>  drivers/ata/libata-core.c | 22 +++++++++++-----------
>  drivers/scsi/scsi_pm.c    | 14 +++++++++++---
>  2 files changed, 22 insertions(+), 14 deletions(-)
> 
> diff --git a/drivers/ata/libata-core.c b/drivers/ata/libata-core.c
> index 497adea..38000fc 100644
> --- a/drivers/ata/libata-core.c
> +++ b/drivers/ata/libata-core.c
> @@ -5355,10 +5355,19 @@ static int ata_port_suspend_common(struct device *dev, pm_message_t mesg)
>  
>  static int ata_port_suspend(struct device *dev)
>  {
> +	int ret;
> +
>  	if (pm_runtime_suspended(dev))
>  		return 0;
>  
> -	return ata_port_suspend_common(dev, PMSG_SUSPEND);
> +	ret = ata_port_suspend_common(dev, PMSG_SUSPEND);
> +	if (!ret) {
> +		__pm_runtime_disable(dev, false);

Don't you mean pm_runtime_disable(dev)?

> +		pm_runtime_set_suspended(dev);
> +		pm_runtime_enable(dev);
> +	}
> +
> +	return ret;
>  }
>  
>  static int ata_port_do_freeze(struct device *dev)
> @@ -5393,16 +5402,7 @@ static int ata_port_resume_common(struct device *dev, pm_message_t mesg)
>  
>  static int ata_port_resume(struct device *dev)
>  {
> -	int rc;
> -
> -	rc = ata_port_resume_common(dev, PMSG_RESUME);
> -	if (!rc) {
> -		pm_runtime_disable(dev);
> -		pm_runtime_set_active(dev);
> -		pm_runtime_enable(dev);
> -	}
> -
> -	return rc;
> +	return 0;
>  }
>  
>  /*
> diff --git a/drivers/scsi/scsi_pm.c b/drivers/scsi/scsi_pm.c
> index d9956b6..d0b6997 100644
> --- a/drivers/scsi/scsi_pm.c
> +++ b/drivers/scsi/scsi_pm.c
> @@ -127,13 +127,21 @@ static int scsi_bus_prepare(struct device *dev)
>  static int scsi_bus_suspend(struct device *dev)
>  {
>  	const struct dev_pm_ops *pm = dev->driver ? dev->driver->pm : NULL;
> -	return scsi_bus_suspend_common(dev, pm ? pm->suspend : NULL);
> +	int ret;
> +
> +	ret = scsi_bus_suspend_common(dev, pm ? pm->suspend : NULL);
> +	if (!ret) {
> +		__pm_runtime_disable(dev, false);
> +		pm_runtime_set_suspended(dev);
> +		pm_runtime_enable(dev);
> +	}
> +
> +	return ret;
>  }
>  
>  static int scsi_bus_resume(struct device *dev)
>  {
> -	const struct dev_pm_ops *pm = dev->driver ? dev->driver->pm : NULL;
> -	return scsi_bus_resume_common(dev, pm ? pm->resume : NULL);
> +	return 0;
>  }

This doesn't look like it would work very well with something like a CD 
drive, which doesn't use block-layer runtime PM.  Is that what you 
meant when you talked about modifying the SCSI PM callbacks?

Alan Stern

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Patch

diff --git a/drivers/ata/libata-core.c b/drivers/ata/libata-core.c
index 497adea..38000fc 100644
--- a/drivers/ata/libata-core.c
+++ b/drivers/ata/libata-core.c
@@ -5355,10 +5355,19 @@  static int ata_port_suspend_common(struct device *dev, pm_message_t mesg)
 
 static int ata_port_suspend(struct device *dev)
 {
+	int ret;
+
 	if (pm_runtime_suspended(dev))
 		return 0;
 
-	return ata_port_suspend_common(dev, PMSG_SUSPEND);
+	ret = ata_port_suspend_common(dev, PMSG_SUSPEND);
+	if (!ret) {
+		__pm_runtime_disable(dev, false);
+		pm_runtime_set_suspended(dev);
+		pm_runtime_enable(dev);
+	}
+
+	return ret;
 }
 
 static int ata_port_do_freeze(struct device *dev)
@@ -5393,16 +5402,7 @@  static int ata_port_resume_common(struct device *dev, pm_message_t mesg)
 
 static int ata_port_resume(struct device *dev)
 {
-	int rc;
-
-	rc = ata_port_resume_common(dev, PMSG_RESUME);
-	if (!rc) {
-		pm_runtime_disable(dev);
-		pm_runtime_set_active(dev);
-		pm_runtime_enable(dev);
-	}
-
-	return rc;
+	return 0;
 }
 
 /*
diff --git a/drivers/scsi/scsi_pm.c b/drivers/scsi/scsi_pm.c
index d9956b6..d0b6997 100644
--- a/drivers/scsi/scsi_pm.c
+++ b/drivers/scsi/scsi_pm.c
@@ -127,13 +127,21 @@  static int scsi_bus_prepare(struct device *dev)
 static int scsi_bus_suspend(struct device *dev)
 {
 	const struct dev_pm_ops *pm = dev->driver ? dev->driver->pm : NULL;
-	return scsi_bus_suspend_common(dev, pm ? pm->suspend : NULL);
+	int ret;
+
+	ret = scsi_bus_suspend_common(dev, pm ? pm->suspend : NULL);
+	if (!ret) {
+		__pm_runtime_disable(dev, false);
+		pm_runtime_set_suspended(dev);
+		pm_runtime_enable(dev);
+	}
+
+	return ret;
 }
 
 static int scsi_bus_resume(struct device *dev)
 {
-	const struct dev_pm_ops *pm = dev->driver ? dev->driver->pm : NULL;
-	return scsi_bus_resume_common(dev, pm ? pm->resume : NULL);
+	return 0;
 }
 
 static int scsi_bus_freeze(struct device *dev)