# High single core CPU usage with 3d Applications (fglrx)

## griever

Hi all,

I'm at wit's end trying to figure out why any application (kwin, steam, glxgears, amdccc) that uses 3d pegs a single core at 100%. This started occurring when I try to run any version of fglrx higher than ati-drivers-13.9. 

I'm running gentoo-sources-3.15.1 and ati-drivers-14.4_p1 on an MSI GX60 laptop.

The cpu is an AMD A10-4600M and the discrete graphics card is an AMD Radeon HD 7970M

I've tried turning VSYNC off and on system-wide. That didn't help (although I did note its effects on cpu usage on other cores).

I started looking into the concept of spinlocks or busy waiting, but there were no obvious ways for me to experiment with it. It's a little beyond what I know.  

But what I DID notice was that if I run glxgears as root, the cpu doesn't max out. It only occurs in my regular user account. Unfortunately I don't know how to turn that tidbit of a finding into anything meaningful. My regular user is already part of the video group.

Does anyone have any ideas?

Thanks,

G

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## StarAUrryon

Hi,

I have a MSI GX60 Hitman Edition 5750m + 7970m

The problem only happened when I use 7970m in my case. I have reported the bug to Amd but until now I have no answer.

I will try to investigate the problem. First I'm On Ubuntu 14.04 Gnome and it seems all Linux Distributions are concerned about it.

If on root there are no problems I will try to find out what happend.

StarAurryon

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## StarAUrryon

Ok you're right there is no issue at root. A little bit strange.

StarAurryon

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## szatox

100% CPU usage on a single core means it's software rendering.

Since it works well when running as root, it seems to be a problem with permissions. A bit weird in days of consolekit, policykit, etckit, but then, shit happens.

How to solve it? Add your users to video group. Users' groups are read upon login, so you might need to relog after that change.

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## StarAUrryon

I don't think it is software rendering as glxgears performances are the same as root and and as user. While running as a simple user two cores are used one has the same amount of charge as root and the second one has full load.

StarAurryon

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## griever

 *szatox wrote:*   

> How to solve it? Add your users to video group. Users' groups are read upon login, so you might need to relog after that change.

 

Thank you for the suggestion. Unfortunately my user is already part of the video group, so that wasn't the issue. Also as user:

```
$ glxinfo | grep direct

direct rendering: Yes
```

```
$ getfacl /dev/ati/card1

# file: dev/ati/card1

# owner: root

# group: root

user::rw-

group::rw-

other::rw-
```

As I understand this output, glxgears isn't software rendering and ACL shouldn't be a problem either.

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