[SOLVED] limit global CPU usage

PolePosition · 2017-12-25 20:42:22

Hello Dear Arch systemd users!

I just got a new laptop (a couple of days ago).
Of course I installed Arch Linux and removed completely Windows 10 !

This laptop is an ASUS Strix GL702ZC, there is inside a AMD Ryzen 7 1700X,
with 8 cores / 16 threads and an AMD RX 580 graphic card.

The battery is empty after 1h 20m. :-(

To save energy and also to make my battery life longer I would like
to do something like that:

- put all threads into a cgroup and limit CPU usage to 80%,
- or deactivate some cores (let's say 4 cores).

all this has to be performed automatically and
could be deactivated by using a script/command line.

What do you think?

Is it possible to create a systemd target, or a systemd config file?
Would be nice that you put me on the best suited track, then I could investigate deeper.

Regards,
Me

Last edited by PolePosition (2017-12-26 12:45:28)

jasonwryan · 2017-12-25 20:50:04

Have you done any power tuning at all? https://wiki.archlinux.org/index.php/Powertop

PolePosition · 2017-12-25 22:17:32

Hi Anarchist!

Thanks, I just gave it a try. I will investigate more deeply as soon as possible.

Also I found how to start Linux with only a certain quantity of activated cores:
when the GRUB menu is displayed, edit the entry to add the option "maxcpus=X" on the line "kernel",
with X the number of core to activate. For instance I tried 2.
I just did it, and the "top" command gives me the confirmation that it works fine.

powertop now tells me why discharge rate is 49W and if I remember right, it was around 62W before.
But I still have to make permanent the powertop recommendation.

Hope all this will help!

It seems strange to deactivate cores as many users, including me like multi-cores systems and powerful systems.
But as explained, I want to prevent my battery to get defect after a year or so... :-/
And 1h20 minutes is clearly short especially if you only edit a TEX file and use XeLaTeX compiler : not a huge workload !

I will keep investigating

Morn · 2017-12-25 23:56:17

The Ryzen CPU has no integrated graphics, so the graphics card is always active and drawing power. So I think this laptop will always be pretty power hungry. (Also note you may have to disable C-state 6 on Ryzen to prevent sudden system reboots on Linux, which also increases power consumption.)

These PC gaming laptops are meant to be mostly plugged into an outlet at all times I think. If you want low power usage during idle and decent gaming performance, get a MacBook Pro.

NoSuck · 2017-12-26 05:14:53

Before installing Arch, did you measure battery life under Windows 10? As the manufacturer's choice of OS, it should provide a base line.

seth · 2017-12-26 09:54:06

According to this (german) review, this is about the battery time you can expect:
https://www.notebookcheck.com/Test-Asus … 470.0.html

It's a "gaming notebook" and you should consider the battery to be a UPS only. It's meant to run on AC.

Morn · 2017-12-26 10:36:03

seth wrote:

According to this (german) review, this is about the battery time you can expect:
https://www.notebookcheck.com/Test-Asus … 470.0.html
It's a "gaming notebook" and you should consider the battery to be a UPS only. It's meant to run on AC.

Yes, it looks like their maximum run time on battery only was about 100 minutes, so Linux is not that far off at 80 minutes.

PolePosition · 2017-12-26 12:45:07

Thanks you all people for having taking the time to answer.
No NoSuck I didn't check what about battery life while using Winblows 10.

I'm gonna investigate :
- make permanent "powertop --auto-tune" changes,
- disable C6 state cause of hang due to Ryzon,
- keeping the option "maxcpus=4" in /etc/default/grub (but I think this does not help at all to reduce power consumption),
- read carrefully the Arch page regarding power saving: https://wiki.archlinux.org/index.php/Laptop

Bye for now,
Me

R00KIE · 2017-12-26 15:29:25

What you could do in addition to doing the tuning recommended by powertop* is limiting the maximum cpu frequency. I do that in my thinkpad e560 with an i7-6500U and during normal usage the fan very rarely turns on. I have never timed the full battery discharge but it's probably good for 6 hours or so with normal usage (not compiling the kernel or using the discrete gpu).

*) Not all recommendations are worth it so change only the minimum necessary to achieve reasonable power savings.

Morn · 2017-12-26 15:49:56

R00KIE wrote:

What you could do in addition to doing the tuning recommended by powertop* is limiting the maximum cpu frequency. I do that in my thinkpad e560 with an i7-6500U and during normal usage the fan very rarely turns on. I have never timed the full battery discharge but it's probably good for 6 hours or so with normal usage (not compiling the kernel or using the discrete gpu).

Yours is not a gaming laptop and can easily get 6-7 hours on a charge according to the notebookcheck.com review. The OP's laptop is a completely different beast and the reviews suggest that 1.75 hours on a charge is the maximum, even on Windows.

I think the OP should have googled "gaming laptop" before spending €1,800. He could have gotten a MacBook Pro for that kind of money and installed Arch on it. Those MBPs last up to 10 hours on a charge according to Apple!

R00KIE · 2017-12-26 16:27:25

For 1800€ you can get proper laptop/ultrabook and not have to worry about/deal with Apple's shenanigans, but to each his own. The OP may be able to squeeze a bit more time out of a battery charge but better not expect to get better than on windows. Now that I've looked at the specifications I'm surprised the battery lasts that long. It is all desktop parts in a laptop form factor, can't expect miracles.

Morn · 2017-12-26 16:46:23

Yes, I think it's a bit too early to go completely AMD on a new notebook as long as there is no Ryzen mobile CPU available yet. And even then they will probably use far more power than an Intel-based notebook with its more efficient switching between integrated and discrete graphics.

It's true, Apple products may not be everyone's cup of tea (especially with their controversial butterfly keyboard mechanism) but I think in terms of running time per charge they are usually quite good compared to regular Windows notebooks. And there are only a few models, so if you want to install Linux I think it is easier because someone probably has everything figured out already. I think the touch bar is the only part that is not supported on Linux, so I would stick to the touch bar-less model in that case.

R00KIE · 2017-12-26 17:04:16

If I'm not wrong AMD has mobile Ryzen APUs with 15W TDP and there are a few manufacturers with announced products based on them, the only question is how low can they go when they idle, apart from that they maybe be a more enticing proposition than equivalent Intel CPUs with integrated graphics but only time will tell.

Morn · 2017-12-26 17:19:09

I have almost the same system as the OP (Ryzen 7 1700, 16 GB, RX 580), albeit as a big HP Omen desktop PC. So I'm certainly not anti-AMD. But I think while AMD is pretty competitive in the desktop segment now, I have my doubts about their mobile CPUs. Certainly power consumption could be a major issue. Which is not a big consideration for a desktop PC for me, but for notebooks, I would stay away from them.

PolePosition · 2017-12-31 10:50:41

Hello guys,

Yes it is possible that there is no possible miracle.
I'll anyway do my best to save a couple of watts.
I have found several ways to achieve such power saving, but i am not sure they are still "the right way to use".
Could you please tell me whether the following webpage is up to date?
https://wiki.archlinux.org/index.php/CP … cy_scaling

For instance, is acpid still a good choice?
I though it is "deprecated" and should be avoided.

If you tell me the webpage is up to date, then I will investigate how to set by default my cpufreq as minimum,
by changing scheduler governor settings. Hope it will help.

Thanks.

Morn · 2017-12-31 12:36:21

Are you sure this machine fits your needs if you are not even a hardcore gamer (which is the target demographic for this laptop)? Perhaps it's not too late to return it to the store.

Although, if you have deleted the Windows recovery partition too, I am not sure if the store will take it back without Windows being installed.

PolePosition · 2018-02-27 11:17:27

Thanks for the tip, but I keep it.
I am using it right now and I love it.
But yes I have the battery duration. :-/

Morn · 2018-02-28 12:35:40

Maybe you could get an external battery for when you are taking the laptop with you? Power banks for smartphones are a thing after all, so I imagine something similar might exist for laptops. There is probably not a lot of space in the laptop for a battery if it has a full-size graphics card, so that might also explain why the battery runs out so fast.

Arch Linux

#1 2017-12-25 20:42:22

[SOLVED] limit global CPU usage

#2 2017-12-25 20:50:04

Re: [SOLVED] limit global CPU usage

#3 2017-12-25 22:17:32

Re: [SOLVED] limit global CPU usage

#4 2017-12-25 23:56:17

Re: [SOLVED] limit global CPU usage

#5 2017-12-26 05:14:53

Re: [SOLVED] limit global CPU usage

#6 2017-12-26 09:54:06

Re: [SOLVED] limit global CPU usage

#7 2017-12-26 10:36:03

Re: [SOLVED] limit global CPU usage

#8 2017-12-26 12:45:07

Re: [SOLVED] limit global CPU usage

#9 2017-12-26 15:29:25

Re: [SOLVED] limit global CPU usage

#10 2017-12-26 15:49:56

Re: [SOLVED] limit global CPU usage

#11 2017-12-26 16:27:25

Re: [SOLVED] limit global CPU usage

#12 2017-12-26 16:46:23

Re: [SOLVED] limit global CPU usage

#13 2017-12-26 17:04:16

Re: [SOLVED] limit global CPU usage

#14 2017-12-26 17:19:09

Re: [SOLVED] limit global CPU usage

#15 2017-12-31 10:50:41

Re: [SOLVED] limit global CPU usage

#16 2017-12-31 12:36:21

Re: [SOLVED] limit global CPU usage

#17 2018-02-27 11:17:27

Re: [SOLVED] limit global CPU usage

#18 2018-02-28 12:35:40

Re: [SOLVED] limit global CPU usage

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