Patchwork [PATCH/RESEND,1/2] Hard disk S3 resume time optimization

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Submitter Todd E Brandt
Date Sept. 6, 2013, 12:38 a.m.
Message ID <20130906003852.GC25263@linux.intel.com>
Download mbox | patch
Permalink /patch/272998/
State Not Applicable
Delegated to: David Miller
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Comments

Todd E Brandt - Sept. 6, 2013, 12:38 a.m.
This is the final draft of the non-blocking hard disk resume patch. I've
included some performance results to demonstrate the real benefits
of this patch. Please note that this patch provides a MASSIVE performance
improvement in hard disk resume. It's too valuable to ignore, so I really
need the help of the maintainers to get this implemented. Even if this
patch is deemed the wrong approach I hope you won't abandon the idea
altogether. There is so much potential in this kind of optimization and
I'm highly motivated to make this work.

To demonstrate the substantial performance improvement I've run the 
AnalyzeSuspend tool on three different platforms patched with the new 
behavior. Each is running Ubuntu Raring with a kernel built from the 
upstream kernel source.

The complete analysis and graphical outputs of the tool are available
online at 01.org:
https://01.org/suspendresume/blogs/tebrandt/2013/hard-disk-resume-optimization-simpler-approach

Here's a synopsis of the results.

-------------------------------------------------------
[Computer One]
PLATFORM: Ubuntu Raring Ringtail (13.04)
KERNEL: 3.11.0-rc7
CPU: Intel(R) Core(TM) i7-3960X CPU @ 3.30GHz
SATA: Intel C600/X79 series chipset 6-Port SATA AHCI (r5)
DISK CONFIG:
    ATA1: 240 GB SSD
    ATA2: 3 TB Hard Disk
    ATA3: 500 GB Hard Disk
    ATA4: DVD-ROM (with cd inserted)
    ATA5: 2 TB Hard Disk
    ATA6: 1 TB Hard Disk
RESUME TIME WITHOUT PATCH: 11656 ms
RESUME TIME WITH PATCH: 1110 ms

IMPROVEMENT: 10.5X speedup

-------------------------------------------------------
[Computer Two]
PLATFORM: Ubuntu Raring Ringtail (13.04)
KERNEL: 3.11.0-rc7
CPU: Intel(R) Core(TM) i7-3770 CPU @ 3.40GHz
SATA: Intel 7 Series/C210 Series Chipset Family 6-port SATA [AHCI mode] (r4)
DISK CONFIG:
    ATA1: 320 GB Hard Disk
    ATA2 - ATA6: Empty slots
RESUME TIME WITHOUT PATCH: 5416 ms
RESUME TIME WITH PATCH: 448 ms

IMPROVEMENT: 12X speedup

-------------------------------------------------------
[Computer Three]
PLATFORM: Ubuntu Raring Ringtail (13.04)
KERNEL: 3.11.0-rc7
CPU: Intel(R) Core(TM) i7-4770S CPU @ 3.10GHz
SATA: Intel Lynx Point 6-port SATA Controller 1 [AHCI mode] (r2)
DISK CONFIG:
    ATA1,3,4,6: Empty Slots
    ATA2: DVD-ROM (empty)
    ATA5: 500 GB Hard Disk
RESUME TIME WITHOUT PATCH: 5385 ms
RESUME TIME WITH PATCH: 688 ms

IMPROVEMENT: 7.8X speedup

-------------------------------------------------------

Signed-off-by: Todd Brandt <todd.e.brandt@intel.com>
Signed-off-by: Arjan van de Ven <arjan@linux.intel.com>

 drivers/ata/libata-core.c | 36 +++++++++++++++++++++++++++++++++++-
 1 file changed, 35 insertions(+), 1 deletion(-)


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Bartlomiej Zolnierkiewicz - Sept. 6, 2013, 4:54 p.m.
Hi,

On Thursday, September 05, 2013 05:38:53 PM Todd E Brandt wrote:
> This is the final draft of the non-blocking hard disk resume patch. I've
> included some performance results to demonstrate the real benefits
> of this patch. Please note that this patch provides a MASSIVE performance
> improvement in hard disk resume. It's too valuable to ignore, so I really
> need the help of the maintainers to get this implemented. Even if this
> patch is deemed the wrong approach I hope you won't abandon the idea
> altogether. There is so much potential in this kind of optimization and
> I'm highly motivated to make this work.
> 
> To demonstrate the substantial performance improvement I've run the 
> AnalyzeSuspend tool on three different platforms patched with the new 
> behavior. Each is running Ubuntu Raring with a kernel built from the 
> upstream kernel source.
> 
> The complete analysis and graphical outputs of the tool are available
> online at 01.org:
> https://01.org/suspendresume/blogs/tebrandt/2013/hard-disk-resume-optimization-simpler-approach

Please include changes descriptions from the link above in the actual patch
descriptions.

"The essential issue behind hard disks' lengthy resume time is the ata
port driver blocking until the ATA port hardware is finished coming online.
So the kernel isn't really doing anything during all those seconds that
the disks are resuming, it's just blocking until the hardware says it's
ready to accept commands. This patch changes the ATA port driver to issue
the wakeup command and then return immediately. Any commands issued to
the hardware will be queued up and will be executed once the port is
physically online. Thus no information is lost, and although the wait
time itself isn't removed, it doesn't hold up the rest of the system
which can function on what's left in RAM and cache."

What happens when somebody requests suspend while ATA port resume is still
running?

> Here's a synopsis of the results.
> 
> -------------------------------------------------------
> [Computer One]
> PLATFORM: Ubuntu Raring Ringtail (13.04)
> KERNEL: 3.11.0-rc7
> CPU: Intel(R) Core(TM) i7-3960X CPU @ 3.30GHz
> SATA: Intel C600/X79 series chipset 6-Port SATA AHCI (r5)
> DISK CONFIG:
>     ATA1: 240 GB SSD
>     ATA2: 3 TB Hard Disk
>     ATA3: 500 GB Hard Disk
>     ATA4: DVD-ROM (with cd inserted)
>     ATA5: 2 TB Hard Disk
>     ATA6: 1 TB Hard Disk
> RESUME TIME WITHOUT PATCH: 11656 ms
> RESUME TIME WITH PATCH: 1110 ms

These results are with both patches applied, could you tell what is
the improvement from the patch #1 alone?

Where is the 11s delay coming from? Are we doing the resume for all 
ports sequentially instead of in parallel? In such case you should be
fixing the power management layer instead.

> IMPROVEMENT: 10.5X speedup
> 
> -------------------------------------------------------
> [Computer Two]
> PLATFORM: Ubuntu Raring Ringtail (13.04)
> KERNEL: 3.11.0-rc7
> CPU: Intel(R) Core(TM) i7-3770 CPU @ 3.40GHz
> SATA: Intel 7 Series/C210 Series Chipset Family 6-port SATA [AHCI mode] (r4)
> DISK CONFIG:
>     ATA1: 320 GB Hard Disk
>     ATA2 - ATA6: Empty slots
> RESUME TIME WITHOUT PATCH: 5416 ms
> RESUME TIME WITH PATCH: 448 ms
> 
> IMPROVEMENT: 12X speedup
> 
> -------------------------------------------------------
> [Computer Three]
> PLATFORM: Ubuntu Raring Ringtail (13.04)
> KERNEL: 3.11.0-rc7
> CPU: Intel(R) Core(TM) i7-4770S CPU @ 3.10GHz
> SATA: Intel Lynx Point 6-port SATA Controller 1 [AHCI mode] (r2)
> DISK CONFIG:
>     ATA1,3,4,6: Empty Slots
>     ATA2: DVD-ROM (empty)
>     ATA5: 500 GB Hard Disk
> RESUME TIME WITHOUT PATCH: 5385 ms
> RESUME TIME WITH PATCH: 688 ms
> 
> IMPROVEMENT: 7.8X speedup
> 
> -------------------------------------------------------
> 
> Signed-off-by: Todd Brandt <todd.e.brandt@intel.com>
> Signed-off-by: Arjan van de Ven <arjan@linux.intel.com>
> 
>  drivers/ata/libata-core.c | 36 +++++++++++++++++++++++++++++++++++-
>  1 file changed, 35 insertions(+), 1 deletion(-)
> 
> diff --git a/drivers/ata/libata-core.c b/drivers/ata/libata-core.c
> index c24354d..6cf0c15 100644
> --- a/drivers/ata/libata-core.c
> +++ b/drivers/ata/libata-core.c
> @@ -5415,6 +5415,40 @@ static int ata_port_resume(struct device *dev)
>  	return rc;
>  }
>  
> +static int ata_port_resume_async(struct device *dev)
> +{
> +	struct ata_port *ap = to_ata_port(dev);
> +	struct ata_link *link;
> +	unsigned long flags;
> +	int ret = 0;
> +
> +	if (ap->pflags & ATA_PFLAG_PM_PENDING) {
> +		WARN_ON(ap->pflags & ATA_PFLAG_PM_PENDING);
> +		ret = -EAGAIN;
> +		goto out;
> +	}
> +
> +	spin_lock_irqsave(ap->lock, flags);
> +
> +	ap->pm_mesg = PMSG_RESUME;
> +	ap->pm_result = NULL;
> +	ap->pflags |= ATA_PFLAG_PM_PENDING;
> +	ata_for_each_link(link, ap, HOST_FIRST) {
> +		link->eh_info.action |= ATA_EH_RESET;
> +		link->eh_info.flags |= ATA_EHI_NO_AUTOPSY | ATA_EHI_QUIET;
> +	}
> +
> +	ata_port_schedule_eh(ap);
> +
> +	spin_unlock_irqrestore(ap->lock, flags);

Why have you open-coded ata_port_request_pm() instead of just re-using it
but with "async" parameter set?

> + out:
> +	pm_runtime_disable(dev);
> +	pm_runtime_set_active(dev);
> +	pm_runtime_enable(dev);
> +	return ret;
> 
> +}
> 
>  /*
>   * For ODDs, the upper layer will poll for media change every few seconds,
>   * which will make it enter and leave suspend state every few seconds. And
> @@ -5451,7 +5485,7 @@ static int ata_port_runtime_resume(struct device *dev)
>  
>  static const struct dev_pm_ops ata_port_pm_ops = {
>  	.suspend = ata_port_suspend,
> -	.resume = ata_port_resume,
> +	.resume = ata_port_resume_async,

->resume will now return success even though it can later fail during
the async operation (error value will be lost), this is no-go, sorry.

Also it seems that ata_port_resume() becomes unused after this change.

>  	.freeze = ata_port_do_freeze,
>  	.thaw = ata_port_resume,
>  	.poweroff = ata_port_poweroff,

Best regards,
--
Bartlomiej Zolnierkiewicz
Samsung R&D Institute Poland
Samsung Electronics

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Brandt, Todd E - Sept. 10, 2013, 8:23 p.m.
Good suggestion on the reuse of the existing ata_port_request_pm function. I have this habit of introducing new changes in such a way that they can be easily turned on and off for testing, but that's not appropriate here. I'll redo this patch with the functionality weaved into all the existing functions instead of creating new ones. Thanks for the feedback!

Todd Brandt
Linux Kernel Developer OTC, Hillsboro OR
https://opensource.intel.com/linux-wiki/ToddBrandt

Patch

diff --git a/drivers/ata/libata-core.c b/drivers/ata/libata-core.c
index c24354d..6cf0c15 100644
--- a/drivers/ata/libata-core.c
+++ b/drivers/ata/libata-core.c
@@ -5415,6 +5415,40 @@  static int ata_port_resume(struct device *dev)
 	return rc;
 }
 
+static int ata_port_resume_async(struct device *dev)
+{
+	struct ata_port *ap = to_ata_port(dev);
+	struct ata_link *link;
+	unsigned long flags;
+	int ret = 0;
+
+	if (ap->pflags & ATA_PFLAG_PM_PENDING) {
+		WARN_ON(ap->pflags & ATA_PFLAG_PM_PENDING);
+		ret = -EAGAIN;
+		goto out;
+	}
+
+	spin_lock_irqsave(ap->lock, flags);
+
+	ap->pm_mesg = PMSG_RESUME;
+	ap->pm_result = NULL;
+	ap->pflags |= ATA_PFLAG_PM_PENDING;
+	ata_for_each_link(link, ap, HOST_FIRST) {
+		link->eh_info.action |= ATA_EH_RESET;
+		link->eh_info.flags |= ATA_EHI_NO_AUTOPSY | ATA_EHI_QUIET;
+	}
+
+	ata_port_schedule_eh(ap);
+
+	spin_unlock_irqrestore(ap->lock, flags);
+
+ out:
+	pm_runtime_disable(dev);
+	pm_runtime_set_active(dev);
+	pm_runtime_enable(dev);
+	return ret;
+}
+
 /*
  * For ODDs, the upper layer will poll for media change every few seconds,
  * which will make it enter and leave suspend state every few seconds. And
@@ -5451,7 +5485,7 @@  static int ata_port_runtime_resume(struct device *dev)
 
 static const struct dev_pm_ops ata_port_pm_ops = {
 	.suspend = ata_port_suspend,
-	.resume = ata_port_resume,
+	.resume = ata_port_resume_async,
 	.freeze = ata_port_do_freeze,
 	.thaw = ata_port_resume,
 	.poweroff = ata_port_poweroff,