Enable SATA DEVSLP

wast3 · 2016-07-29 08:43:20

So, hdparm -I /dev/sda tells me that my SSD (Samsung 850EVO) supports Device Sleep (DEVSLP), but it is not enabled. Also "Device-initiated interface power management" is supported but not enabled.

What can I do to enable these power saving measures? I am on a Thinkpad T430s (Ivybridge)

Thanks!

R00KIE · 2016-07-29 14:31:25

I can't be of much help but I should warn you that with some ssds enabling power saving technologies can lead to data loss, so make sure you have good backups before starting to try things.

Maybe you can start by enabling SATA ALPM and see if what you want to enable gets enabled along with it.

wast3 · 2016-07-30 07:06:25

I do have ALPM enabled. At a second look, both Host-initiated interface power management and Device-initiated interface power management are enabled most of the times.
Only Device Sleep (DEVSLP) is never checked.

I am interested in what other people see in their hdparm -I. Do you have device sleep enabled?

Cheers

R00KIE · 2016-07-30 10:31:50

It seems to be enabled here, not that I have explicitly enabled it, I have just enable sata alpm, and I have it enabled mostly to allow the cpu to go into deeper power saving states as there are reports of data loss when enabling sata alpm.

That said, I suspect that there are SSDs that report support for some features but don't actually support them properly, all I can say is update to the latest available firmware and see if it helps.

This is what I get with the SSD I'm using:

Commands/features:
	Enabled	Supported:
	   *	SMART feature set
	   *	Power Management feature set
	   *	Write cache
	   *	Look-ahead
	   *	WRITE_BUFFER command
	   *	READ_BUFFER command
	   *	NOP cmd
	   *	DOWNLOAD_MICROCODE
	   *	Advanced Power Management feature set
	   *	48-bit Address feature set
	   *	Mandatory FLUSH_CACHE
	   *	FLUSH_CACHE_EXT
	   *	SMART error logging
	   *	SMART self-test
	   *	General Purpose Logging feature set
	   *	WRITE_{DMA|MULTIPLE}_FUA_EXT
	   *	64-bit World wide name
	   *	IDLE_IMMEDIATE with UNLOAD
	    	Write-Read-Verify feature set
	   *	WRITE_UNCORRECTABLE_EXT command
	   *	{READ,WRITE}_DMA_EXT_GPL commands
	   *	Segmented DOWNLOAD_MICROCODE
	    	unknown 119[8]
	   *	Gen1 signaling speed (1.5Gb/s)
	   *	Gen2 signaling speed (3.0Gb/s)
	   *	Gen3 signaling speed (6.0Gb/s)
	   *	Native Command Queueing (NCQ)
	   *	Phy event counters
	   *	NCQ priority information
	   *	READ_LOG_DMA_EXT equivalent to READ_LOG_EXT
	   *	DMA Setup Auto-Activate optimization
	   *	Device-initiated interface power management
	    	Asynchronous notification (eg. media change)
	   *	Software settings preservation
	   *	Device Sleep (DEVSLP)
	   *	SMART Command Transport (SCT) feature set
	   *	SCT Write Same (AC2)
	   *	SCT Features Control (AC4)
	   *	SCT Data Tables (AC5)
	   *	reserved 69[3]
	   *	reserved 69[4]
	   *	reserved 69[7]
	   *	DOWNLOAD MICROCODE DMA command
	   *	WRITE BUFFER DMA command
	   *	READ BUFFER DMA command
	   *	Data Set Management TRIM supported (limit 8 blocks)
	   *	Deterministic read ZEROs after TRIM

Device Sleep:
	DEVSLP Exit Timeout (DETO): 50 ms (drive)
	Minimum DEVSLP Assertion Time (MDAT): 10 ms (drive)

wast3 · 2016-07-30 11:18:48

I got it.
DEVSLP only works on Haswell and newer.

Thank you though

Arch Linux

#1 2016-07-29 08:43:20

Enable SATA DEVSLP

#2 2016-07-29 14:31:25

Re: Enable SATA DEVSLP

#3 2016-07-30 07:06:25

Re: Enable SATA DEVSLP

#4 2016-07-30 10:31:50

Re: Enable SATA DEVSLP

#5 2016-07-30 11:18:48

Re: Enable SATA DEVSLP

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