CPU locked to 100% usage (FS-UAE on Linux / nVidia)

OS : Xubuntu 13.04
FS-UAE : 2.2.3 (taken from PPA)
CPU : i7 @ 3.4GHz
GPU : GTX295 (using official nvidia drivers)
Additional : Dual monitors in Seperate X screen mode.

Problem:

I use GkrellM to monitor CPU usage and I noticed that when FSUAE is running one processor core will be permanently locked to 100% usage causing it to get hot.

Closing FSUAE returns the core to normal operating levels.

Can anyone else check to see if they have the same issue? Any ideas for what might be causing it?

Thanks.

[diablothe2nd]

No problems for my on my 6 core Phenom II black edition. the load is spread. but then i'm using windows 7

using FS-UAE 2.2.3

have you tried changing the NICE value of it? and is there anything similar to "Set Affinity" like on windows where you can force it to use so many cores?

[FrodeSolheim]

@Toxicshadow, you haven't posted config nor log file, so that forces me to a bit of guessing. I assume you're not running with the A4000/040 model or similar - that'll definitively use 100% CPU (fastest-possible emulation).

There's a known "problem" with at least the nVIDIA binary drivers on Linux, where the driver uses some kind of busy-loop to wait for vblank (or so it seems). This problem (if that's what you have) can be remedied by either:
- Using video_sync = off (will introduce tearing)
- Experiment with the video_sync_method option.

Both options can be set in the FS-UAE Launcher preferences GUI.

I too use nVidia binary drivers on Linux, and I get best results with the swap-fence sync method. From the FS-UAE options documentation:

Set a fence after swapping buffers and poll periodically (with sleeps) for completion of swap. This seems to work very well on Linux with recent nVIDIA drivers.

The reason this isn't automatically default is that there isn't a single sync method that works best on all platforms / OpenGL drivers (Though I may perhaps set the default based on checking the OpenGL driver vendor in the future).

@FrodeSolheim. Thank you for responding so quickly. I apologize for the lack detail in the report.

Your suggestion of using "swap-fence" worked perfectly. Originally I left it at "Default" which definitely causes it to lock at 100%. I hope Nvidia can fix their drivers because I suspect a number of other developers may get caught out by this issue.

I guess things may change when the battle between Mir and Wayland starts.

On behalf of Linux users everywhere I would like to say thank you for your hard work and I look forward to any new additions to FSUAE.