Any way to find what processes/systems are using softirqd?
 

I have noticed that whenever I run KDE4 I have two ksoftirqd processes (I am assuming one per core) constistantly using 20-40% of my CPU. I have tried disabling certain modules and my guess is that the culprit is the fglrx module, but I have no way to know for sure. Is there a way to check to see what is calling the interrupts?

I could not find a command to identify a process's parent, though I'm sure there is one, but this command will print a process tree. Maybe it will help.

I know that the softirqd is a process that is spawned by the kernel to queue interrupts whenever there is a higher load than the hardware interrupts can handle. So, I don't think that finding the parent will solve the issue but thanks for the suggestion.

P.S. Running ps -Af will show you the parent process (as well as pstree). The parent of softirqd is kthreadd which is not a normal process but is part of the kernel AFAIK.

Not from userspace.
There are tools out there that should do it, but all have a reasonable learning curve - LTTng, perf, ftrace, systemtap ...

Might be easiest to pull the proprietary driver.

Bear in mind that "k" in the name of a process can refer either to "KDE" or to "Kernel."

Kernel processes are literally "part of the kernel." They execute as dispatchable processes (under privileged rules of order), executing code in kernel-space, to handle those "kernel" duties that are most agreeably defined as being asynchronous.

Yeah, I knew that ksoftirqd wasn't part of KDE, it just seemed to happen whenever KDE4 was running. I couldn't figure out how to install LTTng but after testing I think I've pretty conclusively found that it's the fglrx module. I don't want to switch back to the open source drivers. I wonder if there is some option in xorg.conf that will solve the problem.