[solved] extreme slowness / frequency scaling weirdness

dgulotta · Tux's lil' helper Joined: 09 Jan 2006 Posts: 88

I have been having some issues with my laptop suddenly becoming extremely slow. I think this may be due to the cpu frequency being set to the lowest level. If I run cpupower frequency-info, it will say something like "hardware limits: 1.20-2.70 GHz ... current policy: frequency should be between 1.20 GHz and 1.20 GHz". The latter number is sometime higher when the computer is not being slow. From what I have read, it seems like this could be due to the computer overheating, but the computer does not seem hot. The "sensors" command reports one sensor at 0 C, one at 127 C, and the other four are between 29 C and 40 C. Is it likely that the sensor giving the 127 C reading is bad and is causing the slowdown? Is it possible/safe to ignore this senor?

eccerr0r · Posted: Fri Jan 09, 2015 10:32 pm Post subject:

What do you mean by "extremely" slow?

Yes, most modern machines will throttle when overheating. But they will throttle when it feels like it. Chances are it won't throttle to a small fraction of its full speed so if you're running 1/10 the speed of "fast" mode it's not likely due to throttling.

You should check that sensor that's stuck at 127C when it's working properly. Likely it will also read 127C, and thus is a red herring and thus safe to ignore it.

You should check what the machine's doing when it's slow, is it swapping? Did you run out of RAM and have no swap? Broken driver?
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Intel Core i7 2700K/Radeon R7 250/24GB DDR3/256GB SSD
What am I supposed watching?

dgulotta · Tux's lil' helper Joined: 09 Jan 2006 Posts: 88

If I try to type or click in any X11 application, there is a noticeable lag --- maybe half a second for most apps but several seconds for Firefox. If Firefox is running, then top reports that Firefox is using 100% CPU. I think other programs report larger than usual CPU usage percentages as well, but I haven't checked too thoroughly. I haven't really tested whether there are any problems outside of X. Restarting X does not fix the problem, but rebooting does, and it sometimes goes away on its own.

I am only using 2GB of memory out of 8GB, so that shouldn't be the problem.

One time the dmesg contained "Monitor-mwait will be used to enter c-3 state" from around the same time the slowness started, but there were other times that I didn't see anything in dmesg. I don't see anything unusual in Xorg.0.log.

I guess I did update my video drivers recently.

Is it normal for the upper limit on the cpu frequency policy to change?

Hu · Moderator Joined: 06 Mar 2007 Posts: 21602

If Firefox et al. are using 100% CPU, that wound account for their slow response and for the high temperature. What is the output of emerge --info? What video drivers do you use?

dgulotta · Tux's lil' helper Joined: 09 Jan 2006 Posts: 88

I am using x11-drivers/xf86-video-intel-2.99.917. However, I did some more testing and I do not think the problem is related to video or X11. I killed X11 and tried running some programs from the console, and they ran at about 1/15 normal speed.

Edit:
I am also having some issues with the power cable and possibly the battery. I previously thought these were unrelated, but now I am not so sure. I have to bend the cable in just the right way to get it to work. This is not unusual for a failing cable, but the strange thing is that the battery will not charge. (By "work" I mean that the laptop will run on AC power. The battery does not charge regardless of whether the laptop is on or off.)

Could this cause the slowdown? Is it likely that the battery is also bad?

Edit:
Replacing the power adapter seems to have fixed the problem.