Arch Linux

RobeeJ

Member

Registered: 2015-03-31

Posts: 1

Lag in MAME caused by usb keyboard input

Decided to change my arcade cabinet OS from Vista to Linux, tried Ubuntu but had lots of issues, all of which I solved apart from video lag which I managed to narrow down to the Microsoft wireless USB keyboard. PS/2 keyboard interface (I-Pac) was almost completely fine, but I just upgraded it to a USB version (I-Pac2) which has the same issue as the MS keyboard.

Threw Ubuntu out of the window (never liked it anyway!) and decided to try Arch as it often gets mentioned when people talk about their cabs running Linux, and doesn't install a load of junk that I don't need or want.

And... same issue.

Symptoms

If I leave MAME running say Pac Man in attract mode, it never appears to lag. If I just have a PS/2 keyboard plugged in, it seems to pretty much be the same. If I plug in a USB keyboard (either MS wireless or I-Pac2) then at almost random moments during gameplay MAME either pauses and then frantically drops anywhere between 5 and 15 frames, at irregular intervals. Sometimes it's fine for a few minutes, then it could glitch for a brief moment once, other times it can glitch a couple of times a minute.

MAME cpu usage is around 20-25%, and never had any issues like this on Vista. The issues I had there were all down to the OS deciding to check for updates (or some other disk thrashing exercise) in the background when I was looking good for a high score.

It only does this if I'm pressing keys though, as long as I don't touch anything, no lag.

Things I've Tried

After an insane amount of googling, I've only come across two things I hoped might help.

Setting autosuspend to -2 (in a file under modprobe.d) didn't help, neither did the other instructions for disabling autosuspend here https://wiki.archlinux.org/index.php/Po … utosuspend.

Installing the linux-ck package (suggested in this thread https://bbs.archlinux.org/viewtopic.php?id=178735), didn't make any difference at all.

Any Suggestions?

Help much appreciated!