The State & Future Of Linux Power Management (2016)

[phoronix]

Phoronix: The State & Future Of Linux Power Management (2016)

Linux's power management and ACPI subsystems maintainer Rafael Wysocki presented at this week's LinuxCon Europe event in Berlin about the state and future of power management in the Linux kernel...

http://www.phoronix.com/scan.php?page=news_item&px=Linux-Power-Management-2016

[sunweb]

I don't get it. What future systems Rafael Wysocki was talking about? I don't have swap, i don't needed it. When i want to suspend my laptop it pushes everything to RAM without touching my hdd. I am not leaving laptop for a week or something, i can open it even in 8 hours and everything would restore normally, it doesn't eat up much battery. And now they want to remove the feature altogether or is this suspend-to-idle could do the same? Because it doesn't sound like it. Is he talking about ReRAM things and bright times when there won't be RAM as it is? But its not going to happen soon anyway. For more then 10 years i've heard about about ReRAM like technologies and they're still "coming soon". Do not simply delete features that just work and will work for alot of devices for many years even after ReRAM will come.

[timofonic]

I don't get it. What future systems Rafael Wysocki was talking about? I don't have swap, i don't needed it. When i want to suspend my laptop it pushes everything to RAM without touching my hdd. I am not leaving laptop for a week or something, i can open it even in 8 hours and everything would restore normally, it doesn't eat up much battery. And now they want to remove the feature altogether or is this suspend-to-idle could do the same? Because it doesn't sound like it. Is he talking about ReRAM things and bright times when there won't be RAM as it is? But its not going to happen soon anyway. For more then 10 years i've heard about about ReRAM like technologies and they're still "coming soon". Do not simply delete features that just work and will work for alot of devices for many years even after ReRAM will come.

Aren't you using SWAP? Do you do resource intensive stuff in your laptop? I see it might be an issue with compiling or opening lots of tabs in the web browser, for example.

I'm quite confused about this, sometimes things aren't explained correctly. I use suspend a lot on my laptop. What about non-mainline features like TuxOnIce? Is this going to be superseeded by new ones in mainline?

And Phoronix these days makes too fastly written news that lack more deep explanation

[JonathanM]

And now they want to remove the feature altogether or is this suspend-to-idle could do the same?

As I understand it suspend-to-idle means that the system is going into a low power mode, but with the OS still active. Think of it as suspending the system in a similar way to how mobile phones are suspended.

[Azrael5]

I continue to have problem on network response after resuming from suspend state. The network is not correctly initialized.

[pal666]

I don't have swap, i don't needed it

then you keep in memory unused data instead of using it as disk cache, i.e. your system is slower than it would be with swap

[vadix]

I don't get it. What future systems Rafael Wysocki was talking about? I don't have swap, i don't needed it. When i want to suspend my laptop it pushes everything to RAM without touching my hdd. I am not leaving laptop for a week or something, i can open it even in 8 hours and everything would restore normally, it doesn't eat up much battery. And now they want to remove the feature altogether or is this suspend-to-idle could do the same? Because it doesn't sound like it. Is he talking about ReRAM things and bright times when there won't be RAM as it is? But its not going to happen soon anyway. For more then 10 years i've heard about about ReRAM like technologies and they're still "coming soon". Do not simply delete features that just work and will work for alot of devices for many years even after ReRAM will come.

I believe they are referring to offloading the RAM to things like Intel XPoint or flash memory, which are non-volatile and would decrease the idle power requirements even more. New flash memory (Samsung) and the upcoming XPoint (Intel Optane) products are going to have incredibly high bandwidths, and we might even see more filesystem caching on architectures like XPoint in the near future. Intel will be releasing DDR4 modules of Intel Optane for servers, so it might filter down to PCs as well.

[caligula]

then you keep in memory unused data instead of using it as disk cache, i.e. your system is slower than it would be with swap

Not necessarily. You make the assumption that the free space could be used for something useful (like caching the filesystem or buffers) and that the speedup from that would benefit more than syncing data to the swap space would slow it down.

[madbiologist]

I don't get it. What future systems Rafael Wysocki was talking about? I don't have swap, i don't needed it. When i want to suspend my laptop it pushes everything to RAM without touching my hdd. I am not leaving laptop for a week or something, i can open it even in 8 hours and everything would restore normally, it doesn't eat up much battery. And now they want to remove the feature altogether or is this suspend-to-idle could do the same? Because it doesn't sound like it. Is he talking about ReRAM things and bright times when there won't be RAM as it is? But its not going to happen soon anyway. For more then 10 years i've heard about about ReRAM like technologies and they're still "coming soon". Do not simply delete features that just work and will work for alot of devices for many years even after ReRAM will come.

Did you look at his slide presentation? Take particular note of slides 9, 10 and 11. It seems that it's not a matter of deleting anything, but it just might not work on future systems.

[Adarion]

I also wonder what exactly suspend-2-idle does and why that should be any better (on today's or future machines) than S2R or S2D. The latter is quite failsafe and for S2R I have come to like it in the recent months.
S2idle sounds dangerously close to MS(R) (TM) (blah) Windows' "connected standby" which makes people think the device is shut down but it's still actively sucking data down the net and uploading god (and Satya N.) knows what. Off should be off. Sadly most small embedded / mobile devices don't have a real HW power switch and from some you can't easily remove the battery.