While monitoring CPU I observed that CPU core 0 (/proc/cpuinfo) is most busy all the time. Our application is multithreaded running in Jboss app server. I would assume that the threads would be scheduled evenly on all the CPU cores (quad core) but it doesn't seem to be the case. There seems to be some problem with schceduling. One CORE (core 0) is always busy and all others are barely not doing anything. My question is what to look for to improve this behaviour. We don't have any affinity set so all threads should be scheduled evenly accross all the cores.

Hi -

My own experience is that JBoss does a pretty good job of scheduling workloads across multiple CPUs.

The first thing you need to do is figure out *which* process is hogging CPU 0. It's very likely a specific process (rather than a bunch of different programs), but it *isn't* necessarily a JBoss-related process.

NOTE:
Discussion continued under this thread:
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I already checked that it's Jboss that takes most of the CPU. I am not sure how to see or where to look to see how threads are being scheduled or how OS is scheduling threads and processes. I am not sure why Core 0 is always busy.