I/O hangs and causes overall system freeze. What do I do?

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vexatious · Post by **vexatious** » Sun Dec 22, 2013 7:49 am

Running Gentoo and Slackware 64bits and getting bad system hangs from I/O the exact same way on both OS's. Both installs share the same home folder.

With MAME, I get a series of hard-locks and system stalls every 45 seconds (HDD activity light blinks like mad like the HDD is doing abunch of loading). This renders playing games completely pointless (I even bought the roms legally from MK Arcade Kollection). I'm also getting problems with my TV-tuner capture card. When I capture lossless data (or even mpeg2 from the hardware encoder), dmesg get's spammed with buffer overflow error messages and my captures result with dropped frames (really jerky and/or corrupt playback).

Everything worked fine before, for the longest time. Actually, I upgraded from an nvidia 9800GTX to an ati HD 7750, and noticed my wireless internet started causing system hangs and packets would got lost. When upgrading from the ati HD 7750 to the nvidia 8400gs, this is when I got worse system hangs (as they are right now). 8400gs also has a dumb problem where everything is scaled to a different resolution (it used a different monitor before I switched to my current one, and it thinks I'm still using the old one); this makes all resolutions look horrid since it doesn't let my display do the scaling.

Also, I tried flashing the 8400gs firmware-bios to alleviate it's stubborn resolution scaling (it does it from POST and even with vesa modes). But this caused an I/O error on /dev/nvidia0, preventing Xorg from starting (startx). Flashing 8400gs back to its original firmware brought Xorg back to working, but I still have dreaded system hangs (and the stupid GPU scaling everything)...

I removed my capture card, moved 8400gs to different pcie slot, unplugged keyboard, switched usb ports, disabled sound card firewire and serial ports, deleted ~/.nvidia-settings.rc, but same problem.

Any help would be wonderfully appreciated.

Sincere regards

EDIT:
Under Windows everything works fine. No hangs with MAME, capture card seems very responsive, no slowdowns. I'm almost positive FGLRX drivers are to blame. I did `sh /usr/share/ati/fglrx-uninstall.sh --force ; rmmod fglrx ; ldconfig` under both Slackware and Gentoo (did `emerge --unmerge ati-drivers ; rmmod fglrx ; merge nvidia-drivers ; eselect opengl set nvidia ; ldconfig ; . /etc/profile ; env-update` under gentoo).

So I'm wondering if the FGLRX drivers did something, or Linux doesn't know how to handle IRQ's as good as Windows?

Regards

darklegion · Post by **darklegion** » Mon Dec 23, 2013 1:43 am

Firstly, I'd recommend going back to the 7750 as the 8400gs is a large downgrade in comparison to the 7750, unless you need specific features from the nvidia card (and I don't think any benefit of performance will come from the somewhat better drivers either, given the weakness of the 8400gs). Alternatively if you still have that 9800gtx you might try going back to that as it's also a lot faster than the 8400gs and probably has fairly similar performance to the 7750 (but at a higher power usage)

Although I don't think this is the cause of your issue since it's also happening with the nvidia card you probably don't want to use FGLRX with the 7750 at this point in time as the open source radeon driver is quite good with anything supported by R600g.

Anyway, if you do go back to the 7750 install the open source radeon drivers with at least mesa 9.2, preferably git mesa to save you having to set R600_DEBUG=sb as it's enabled by default. Additionally, install a recent kernel of at least 3.11 and enable radeon.dpm=1 on the kernel command line.

That all being said, the issue may well be i/o or cpu scheduler related. On the I/O side you could experiment with using a different i/o scheduler such as deadline. On the CPU side, try patching your kernel with BFS from here http://ck-hack.blogspot.com.au/

vexatious · Post by **vexatious** » Tue Dec 24, 2013 1:49 am

Upon further testing I found Windows has about 50ms input lag (xbox 360 controller) in MAME. Linux, despite using 300hz timer, has 0 lag (everything's instant despite hangs every 45 seconds). I'm guessing something is wrong with PCI latency but this is by far the worst case I've had. Guess I really do need to buy a video card (have two PCIE16x slots and problem persists in either one with 8400gs). Linux seems better at showing these flaws rather than hiding them like Windows maybe (which is good IMO)...

As a note I'm using the 8400gs with newer core (less shaders vs old one).

Going to purchase new card (going to have to sell laptop=arrrrgh) and hopefully problems will go away. Want to go NVIDIA but lack of open source support and this experience leaves a disturbing taste in my mouth. Nvidia binary drivers do support custom modelines just fine which is a must for MAME, whereas I need to hack an EDID file with custom modelines for FGLRX (400x254@109hz on CRT is a must for Mortal Kombat games; you get crisp display with natural hardware scanlines and rock solid vsync with 0 lag. Way better than MK Arcade Kollection frontend with typical interpolation scaling).

vexatious · Post by **vexatious** » Tue Dec 24, 2013 2:55 pm

SOLVED

Stupid me. I was telling MAME to record gameplay into MNG, AVI, and WAV files through its ini settings file. Disabled that and problem is gone! Cancelled my order for new video card and hope that they don't ship it now lol. Reason I went with 8400GS is it's fanless and I'm a retro gamer (my brother has the 7750). Many thanks!