** Description changed:
On some NVMe devices which have slower power states transition time,
APST wasn't enabled by default on those NVMes.
In order to make APST enabled on more NVMes, we need to relax the
default APST latency limit.
+
+ [Impact]
+ NVMe consumes lots of power. It may not be an issue on power cord plugged
devices, but it will reduce usage time on battery powered devices.
+
+ APST is enabled but it can't find power saving state to transits to:
+
+ $ sudo nvme get-feature -f 0x0c -H /dev/nvme0
+ get-feature:0xc (Autonomous Power State Transition), Current value:0x01
+ Autonomous Power State Transition Enable (APSTE): Enabled
+ Auto PST Entries.
+ Entry[ 0]
+ .
+ Idle Time Prior to Transition (ITPT): 0 ms
+ Idle Transition Power State (ITPS): 0
+ .
+ Entry[ 1]
+ .
+ Idle Time Prior to Transition (ITPT): 0 ms
+ Idle Transition Power State (ITPS): 0
+ ...
+
+ [Test Case]
+ APST is enabled, also there's power saving state (3) to transit to:
+
+ $ sudo nvme get-feature -f 0x0c -H /dev/nvme0
+ get-feature:0xc (Autonomous Power State Transition), Current value:0x01
+ Autonomous Power State Transition Enable (APSTE): Enabled
+ Auto PST Entries.
+ Entry[ 0]
+ .
+ Idle Time Prior to Transition (ITPT): 500 ms
+ Idle Transition Power State (ITPS): 3
+ .
+ Entry[ 1]
+ .
+ Idle Time Prior to Transition (ITPT): 500 ms
+ Idle Transition Power State (ITPS): 3
+ ...
+
+ [Regression Potential]
+ Low.
+
+ We already enabled APST on X/Y for a while, this SRU will include more NVMes
to enable APST.
+ If any regression happens, user can disable APST in kernel parameter.
+ I'll also add new quirk for those devices.
+
+ Either way, NVMe APST is enabled by default from 4.11 onward - if faulty
+ NVMes need to be quirked, it's better be sooner rather than later.
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https://bugs.launchpad.net/bugs/1700919
Title:
Enable APST for more NVMe
Status in linux package in Ubuntu:
Incomplete
Bug description:
On some NVMe devices which have slower power states transition time,
APST wasn't enabled by default on those NVMes.
In order to make APST enabled on more NVMes, we need to relax the
default APST latency limit.
[Impact]
NVMe consumes lots of power. It may not be an issue on power cord plugged
devices, but it will reduce usage time on battery powered devices.
APST is enabled but it can't find power saving state to transits to:
$ sudo nvme get-feature -f 0x0c -H /dev/nvme0
get-feature:0xc (Autonomous Power State Transition), Current value:0x01
Autonomous Power State Transition Enable (APSTE): Enabled
Auto PST Entries.
Entry[ 0]
.
Idle Time Prior to Transition (ITPT): 0 ms
Idle Transition Power State (ITPS): 0
.
Entry[ 1]
.
Idle Time Prior to Transition (ITPT): 0 ms
Idle Transition Power State (ITPS): 0
...
[Test Case]
APST is enabled, also there's power saving state (3) to transit to:
$ sudo nvme get-feature -f 0x0c -H /dev/nvme0
get-feature:0xc (Autonomous Power State Transition), Current value:0x01
Autonomous Power State Transition Enable (APSTE): Enabled
Auto PST Entries.
Entry[ 0]
.
Idle Time Prior to Transition (ITPT): 500 ms
Idle Transition Power State (ITPS): 3
.
Entry[ 1]
.
Idle Time Prior to Transition (ITPT): 500 ms
Idle Transition Power State (ITPS): 3
...
[Regression Potential]
Low.
We already enabled APST on X/Y for a while, this SRU will include more NVMes
to enable APST.
If any regression happens, user can disable APST in kernel parameter.
I'll also add new quirk for those devices.
Either way, NVMe APST is enabled by default from 4.11 onward - if
faulty NVMes need to be quirked, it's better be sooner rather than
later.
To manage notifications about this bug go to:
https://bugs.launchpad.net/ubuntu/+source/linux/+bug/1700919/+subscriptions
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