I’ve recently taken delivery of a Dell M4800 with an AMD FirePro M5100 Mobility Pro graphics card (according to Dell) or a Advanced Micro Devices, Inc. [AMD/ATI] Venus XT [Radeon HD 8870M] (according to lspci). I have three monitor configurations that I use:
As a laptop using the LVDS screen
Plugged into a KVM at home and connected via the HDMI port to a Samsung SMB2430L monitor
In a docking station at work, which is connected to a Dell 2208WFP via the dock DVI connector and a Dell 1901FP via the dock VGA connector
I have the xf86-video-ati-7.2.0-2.1.2.x86_64 drivers installed. I’ve also tried using the fglrx drivers but have been having problems with the HDMI output leading me to abandon them. Both the radeon and fglrx drivers show similar behaviour.
If I use configuration 1 or 2, then everything is reasonably good. The system is responsive and, using ksysguard, I can see that programs are behaving reasonably.
If I use configuration 3, then the system is very sluggish. Programs that were quick under configurations 1 and 2 now seem to use a lot of CPU, graphics performance slows. It’s noticable that if I have ksysguard showing the system load graph, then both ksysguard and Xorg both start consuming a CPU at 40-60% whereas if I have it on the process table tab, then CPU usage drops to 0-20%. Programs such as firefox and thunderbird are very slow and unresponsive and often max out a processor or two and stellarium and google-earth both chew through CPU cycles. On configurations 1 and 2 these programs don’t need a great deal of CPU.
I’ve tried unplugging the VGA monitor, but there doesn’t seem to be any change in performance. Trying to use the EXA option instead of glamor marginally improves general performance but utterly kills the 3D applications.
I have the dynamic switchable graphics turned off in the BIOS.
My previous laptop handled all these configurations perfectly (with an nvidia card; I don’t get to choose, unfortunately)
I’ve tried switching to kernel 3.15, since there seems to have been some problems with glamor and drawing primitives without luck.
I’ve disconnected the dock and tried plugging the displays individually into the VGA port on the laptop (no HDMI-DVI adaptor) wihtout luck
I’ve tried installing the fglrx drivers, also without luck. The AMD catalyst lists the card as an AMD Radeon R9 M270X
I have discovered that if I start the laptop in the dock with the power to the dock off, then the graphics system behaves itself. I can then plug the power in and the system still behaves itself.
However, any configuration with the external power plugged in at the start and it seems to start having problems.
Could anyone shed any light as to what is going on?
Are there any hints wrt messages in the log files ?
After you plug the laptop into the docking station (with power applied) are there any entries in /var/log/messages and also in /var/log/Xorg.0.log file that may provide some clues ?
In both cases the power was off. It was then either put into the docking station and powered on or powered on as a stand-alone laptop.
I have a hypothesis, which I need to gather data on, that the power adapter at home and the power adapter for the dock have different ratings. The dock adapter may have a lower rating which is causing the GPU to shut down to conserve energy. The result being that graphics processing is being offloaded onto the CPU. This doesn’t explain why battery power is OK but I think it’s worth exploring.
The dock adapter is a DA130PEI, 19.5V 6.7A. The adapter supplied with the laptop is a DA180PM111, 19.5V 9.23A. Switching the adapters on the dock solves the problem. So an immediate fix is to get the adapter updated.
It doesn’t explain why everything is just fine without external power, however. Or what is causing the switch in behaviour. Since I’m seeing some odd charging behaviour when the good adapter is plugged in directly; the battery doesn’t run down but it doesn’t charge, either; it charges when plugged into the dock.
I also can’t see where all the power is going. The GPU is running a little hot (55C) as is the CPU (45C) compared to my desktop system. But it’s nothing major, the fans are not running noticably, the battery discharge is 1900mA and I wouldn’t have thought that the extra couple of amps should make a difference.
Are there any experts in how X11 chooses its rendering strategy or how linux manages power out there?
Sounds more like how the hardware handles it. Using the external power there may be a bleed to the dock which would be why the battery is not charging. Have no idea about the odd video though.