Weird microlag in stepmania.

I get these little lag spikes that only last a few ms while playing stepmania. Its very annoying. Stepmania is normally getting 1600-5000 FPS depending while playing stepmania/menu’s so it usually runs super good but just these micro lags that piss me off.

I tried disabling intel turbo (incase that was causing it) but one thing I have noticed is my machine seems like it has a huge number of interrupts/sec gaming or not. I don’t think ive ever seen it under 30k interrupts/sec even when idle. Here is while I am playing the game:

04:01:40 PM CPU %user %nice %sys %iowait %irq %soft %steal %idle intr/s
04:01:50 PM all 3.07 0.00 0.15 0.02 0.00 0.01 0.00 96.76 32366.93
04:02:00 PM all 3.77 0.00 0.12 0.02 0.00 0.00 0.00 96.10 32445.20
04:02:10 PM all 3.12 0.00 0.10 0.02 0.00 0.00 0.00 96.76 32452.90
04:02:20 PM all 3.12 0.00 0.10 0.03 0.00 0.01 0.00 96.74 32418.30
04:02:30 PM all 3.13 0.00 0.09 0.02 0.00 0.00 0.00 96.76 32456.40
04:02:40 PM all 3.26 0.00 0.11 0.02 0.00 0.01 0.00 96.61 32412.80
04:02:50 PM all 3.13 0.00 0.09 0.02 0.00 0.00 0.00 96.76 32368.50
04:03:00 PM all 3.21 0.00 0.12 0.02 0.00 0.01 0.00 96.65 32528.50
04:03:10 PM all 3.14 0.00 0.10 0.02 0.00 0.01 0.00 96.74 32388.81
04:03:20 PM all 3.13 0.00 0.10 0.02 0.00 0.00 0.00 96.74 32428.40
04:03:30 PM all 3.12 0.00 0.12 0.02 0.00 0.01 0.00 96.74 32425.90
04:03:40 PM all 3.29 0.00 0.10 0.02 0.00 0.00 0.00 96.59 32422.30
04:03:50 PM all 3.13 0.00 0.11 0.02 0.00 0.01 0.00 96.73 32393.00
04:04:00 PM all 3.16 0.00 0.10 0.02 0.00 0.01 0.00 96.72 32449.10
04:04:10 PM all 3.12 0.00 0.09 0.02 0.00 0.00 0.00 96.77 32426.40
04:04:20 PM all 3.78 0.00 0.13 0.02 0.00 0.00 0.00 96.05 32481.40

Here is idle:

04:20:44 PM CPU %user %nice %sys %iowait %irq %soft %steal %idle intr/s
04:20:54 PM all 0.47 0.00 0.12 0.03 0.00 0.01 0.00 99.38 32924.40
04:21:04 PM all 0.28 0.00 0.11 0.03 0.00 0.00 0.00 99.57 32531.50
04:21:14 PM all 0.45 0.00 0.12 0.03 0.00 0.01 0.00 99.39 32887.90
04:21:24 PM all 0.33 0.00 0.09 0.02 0.00 0.01 0.00 99.55 32500.00
04:21:34 PM all 0.29 0.00 0.11 0.02 0.00 0.01 0.00 99.58 32525.20
04:21:44 PM all 0.50 0.00 0.14 0.02 0.00 0.01 0.00 99.33 32975.70
04:21:54 PM all 0.42 0.00 0.10 0.02 0.00 0.00 0.00 99.46 32647.80
04:22:04 PM all 0.41 0.00 0.14 0.03 0.00 0.01 0.00 99.41 32808.10

Anyone have any ideas? I have also tried forcing the videocard to use max performance as well to no avail.

As you can see not a huge difference in interrupts here… It also seems really high. Here is my workstation machine using an identically configured kernel running a significantly heavier xorg configuration (4 monitors with xgl) and its interrupts are way lower:

I was thinking maybe the massive amount of interrupts is what is causing the lag… maybe not though. Does anyone have any suggestions?

As you say, it’s most likely the huge number of interrupts that are preventing the game from being smooth, grabbing the CPU’s attention so often. Check what’s causing it (maybe Ethernet):

cat /proc/interrupts