I'm running into an annoying performance issue with the Websphere RT 3.0 VM. Whenever I run a Java application (even a plain old non-RTSJ application) in real-time mode (i.e. with -Xrealtime) Swing performance becomes unpredictable and choppy. My gut feeling is that something is fighting over a spinlock. Specifically, whenever the app needs to repaint the JVM process CPU usage pegs at 100% for a few moments, long enough to ensure that the app can't even sustain a 2 Hz screen update rate. If the same app is run without the -Xrealtime flag, CPU usage is so low that programs like 'top' won't even detect it. Anyone have any suggestions for things to try/probe?
java version "1.7.0"
WebSphere Real Time V3 (build pxi3270sr3hrt-20121025_01(SR3))
IBM J9 VM (build 2.6, JRE 1.7.0 Linux x86-32 20121024_126071 (JIT enabled, AOT enabled)
J9VM - R26_Java726_SR3_20121024_1635_B126071
JIT - r11.b02_20120924_26343a
GC - R26_Java726_SR3_20121024_1635_B126071
J9CL - 20121024_126071)
JCL - 20121019_01 based on Oracle 7u6-b17
Pinned topic Swing Performance Issue with the Websphere RT 3.0 VM
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Updated on 2012-12-01T20:23:43Z at 2012-12-01T20:23:43Z by SystemAdmin
SystemAdmin 110000D4XK2736 Posts
Re: Swing Performance Issue with the Websphere RT 3.0 VM2012-12-01T20:23:43ZThis is the accepted answer. This is the accepted answer.As luck would have it, right after I posted this I was able to "get things to work." I tried to force opengl acceleration for java2d using the -Dsun.java2d.opengl=true flag, and the performance is now what I would expect given the hardware. Perhaps the -Xrealtime flag disables certain hardware acceleration by default?