Dell Precision M6800 Linux Guide/Review

* Hardware

My model of M6800 comes with i7 4800MQ CPU, Quadro K3100M graphics, 4*4GB memory, 256GB Samsung ssd and Intel 7260ac wifi.

* Installation and configuration

Considering the CPU, GPU and wifi hardwares are quite new, Linux distributions with relatively new kernel is recommended. For example, the Intel p-state driver (for Haswell CPU power saving) is in the kernel since Linux 3.9, and the Intel 7260ac wifi driver is in the kernel since Linux 3.10.

The GPT partition table and EFI boot method are used here. There are also boot options with MBR/BIOS boot, which also works (tested on live CD but not installed systems).

For graphics, bumblebee with Nvidia propriety driver is installed for Optimus support (need to be turned on in BIOS, which is by default already turned on in my case). The system uses integrated graphics completely, unless commands are run explicitly using optirun or primusrun. Bbswitch is installed together with bumblebee to automatically switch off the quadro card when it is not needed.

There is one non-standard tweak that I liked: considering I don't use the trackpoint a lot, the mouse keys right below the space bar are not quite useful for me. Thus I re-configured them to be additional function keys, which can be hotkeys (kde runner, switch virtual desktop, switch applications, in my case). This can be done by first remap those buttons:

xinput set-button-map "DualPoint Stick" 20 21 22 23 24

And then use easystroke to map those buttons to keys.

Distribution-wise, I am on archlinux and things work well. I tried OpenSUSE 13.1 previously, and there were some issues (maybe because of X-server version). Namely emacs doesn't update cursor position correctly, and Mathematica scrolling (page up/page down) crashes the whole X-server. Inkscape refuses to start with optirum / primusrun on OpenSuse either but starts well on archlinux.

I do have an issue on archlinux: CUDA 5.5 is not compatible with the gcc version 4.8. This seems solve-able when I googled, but I am currently not using CUDA thus left this issue uninvestigated. This is a distribution related issue thus it may not happen on other Linux distributions.

* Temperature / noise

I haven't run with full load on this laptop yet. But from simple tests, I am happy with the temperature and there is no heat issue.

The idle CPU temperature is about 45~55C. In this temperature range the laptop is completely silent. A few times in an hour, the fan kicks in for a few seconds (or occasionally longer), when the heat accumulates. Even for those a few seconds, the fan noise is not as loud as my previous Dell Studio 1557's constant noise. The only annoying detail is that, when the fan starts to spin, at the very first moment it is a bit loud (similar to optical drive noise). But the noise is acceptable for me.

When CPU is on 100% load (single thread), the fan is on constantly, but only with low speed. The CPU temperature is about 70C (this is for the highest of the 4 cores; the coolest core is about 59C). Turbo boost is on (as I can see from /sys/devices/system/cpu/intel_pstate) and maintains the highest frequency (considering the temperature). The information in /proc/cpuinfo reports that the CPU stays at about 3699 MHz.

* Battery Life

TLP is installed for tunings on power saving. Some additional power saving is turned on in TLP, following powertop suggestions.

Note that on Linux kernel 3.9 or later, the CPU power is managed by a "p-state" driver instead of CPUfreq. The p-state driver works out of the box, and we don't need to set power governor to ondemand as in older systems.

On battery, powertop reports 13.3W ~ 13.7W power consumption when idle, which is slightly more than 8 hours battery life (97Wh battery. well, the math doesn't seem correct but this is what reported). This result is comparable with reviews of this laptop on Windows.

* Other feelings

I consider this laptop as very well-built. It is indeed heavy but otherwise one can hardly find any short comings.

* Note added:

After longer time usage and test, there are indeed a few problems

(1) The SD card reader is not working (workaround: see #3 of this thread). The hardware is [1217:8520]. I searched and found it is a known problem. Patches are submitted to the kernel developers thus it is expected to work in future kernels.

(2) The touchpad sometimes give "lost sync" error. At times (a few times in a day) there are a few random mouse actions. This is again a driver issue. A few workarounds can be found on archlinux wiki.

(3) The wifi hardware switch (in the BIOS it is mentioned that on Win8 it doesn't work either). But I don't need it essentially.

(4) Adjusting screen backlight brightness could be slow. A workaround is on #4.

 

Some benchmarks:

systester 1.5.1, Borwein algorithm, Pi digits: 1M

1 thread -- 3.428s
2 threads -- 3.763s
4 threads -- 4.932s
8 threads -- 9.533s

GpuTest 0.6.0 test results, run at 1920x1080.

Code:

| Tests              | Intel 4800MQ  | Optirun K3100M  | Primusrun * K3100M |
| Furmark            | 393 (6 FPS)   | 1492 (24 FPS)   | 1545 (25 FPS)      |
| Pixmark Volplosion | 289 (4 FPS)   | 632 (10 FPS)    | 641 (10 FPS)       |
| Tessmark           |               | 12651 (210 FPS) | 8495 (141 FPS)     |
| Gimark             |               | 3573 (59 FPS)   | 3967 (66 FPS)      |
| Plot3D             | 3492 (65 FPS) | 14382 (239 FPS) | 8396 (139 FPS)     |

* Here "vblank_mode=0 primusrun command" is used.

Compile Linux Kernel 3.12.4 (almost archlinux default options, -j5): 14min.

 

More about the SD card reader:

Currently the simplest thing to do may be to wait the driver to come into a newer Linux kernel. But in case we want it to work as quickly as possible, one can apply the following patch (tested, worked for me):

https://lkml.org/lkml/2013/10/28/208

Here is how to do it under Arch Linux. You may need to follow the guide for your distribution how to apply patches if you use other distribution.

==========

1. Save the patch as a file (my copy-and-paste: https://dl.dropboxusercontent.com/u/49916494/mmc.patch).

2. Setup the Arch Build System.

3. Edit PKGBUILD (mine: https://dl.dropboxusercontent.com/u/49916494/PKGBUILD_linux3p12_wangyi)

4. makepkg and install

5. If you use bbswitch (usually comes with bumblebee) or nvidia property driver: either install the dkms version of them, or build the kernel modules by hand again

6. Update grub using grub-mkconfig -o /boot/grub/grub.cfg. (Note: I met a bug running this command. I have to add GRUB_DISABLE_SUBMENU=y into /etc/default/grub before running grub-mkconfig).

More about the touchpad:

Currently there seems no perfect solution. One workaround is to use the psmouse module with parameter proto=exps. But then scroll is lost. I am using right key drag as scroll for the time being.

To change the parameter of psmouse immediately (but lost after reboot)

Code:

sudo modprobe -r psmouse; sudo modprobe psmouse proto=exps

To make the change permanent: add the following line to /etc/modprobe.d/modprobe.conf (create file if non-exist)

Code:

options psmouse proto=exps

 

Another issue: adjusting brightness is very slow on this machine.

Workaround: directly change /sys/class/backlight/intel_backlight/brightness directly, and bind the change onto a hotkey.

Here is explicit steps:

(1) Let ordinary user change this file: sudo chmod a+w /sys/class/backlight/intel_backlight/brightness

(2) Create following scripts:

wy_bl_inc.sh

Code:

BL_FN=/sys/class/backlight/intel_backlight/brightness
BL_MAX=5280
BL_MIN=30
BL_INC=$(expr 100 + $(cat $BL_FN) / 6)

wy_bl_num_after_inc () {
  if [ $(cat $BL_FN) -ge $(expr $BL_MAX - $BL_INC) ] ; then
    echo $BL_MAX
  else
    echo $(expr $(cat $BL_FN) + $BL_INC)
  fi;
}

echo $(wy_bl_num_after_inc) > $BL_FN

wy_bl_dec.sh

Code:

BL_FN=/sys/class/backlight/intel_backlight/brightness
BL_MAX=5280
BL_MIN=30
BL_INC=$(expr 100 + $(cat $BL_FN) / 6)

wy_bl_num_after_dec () {
  if [ $(cat $BL_FN) -le $(expr $BL_MIN + $BL_INC) ] ; then
    echo $BL_MIN
  else
    echo $(expr $(cat $BL_FN) - $BL_INC)
  fi;
}

echo $(wy_bl_num_after_dec) > $BL_FN

(3) Bind them onto hotkeys.

==========

Note: There are some other suggestions on internet, for example add kernel boot parameter acpi_backlight=vendor, acpi_backlight=legacy, acpi_osi=Linux, etc. Unfortunately, none of them work for me.

 

Nice guide. Still debating on Windows vs Linux for next semester, going into computer science. Don't ask me to dual boot, my SSD is only big enough for one OS and my HDD is too slow to hold an OS.

 

Op thanks for this very informative contribution, overall are you happy with the 6800? TIA, josea

 

I have listed all the annoying things (and most of them have fixes) I have found. An overall impression depends on how one minds about them. Personally I don't mind and I am very happy with this machine.