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Hints and Troubleshooting

How to check for the Instrumented Kernel mode

When in Instrumented Kernel mode, nothing is visibly different. The performance won't noticeably change either. Thus, it can be tough to tell whether you've successfully changed into Instrumented Kernel mode. And forgetting to start the Instrumented Kernel is something we all do once in a while.

To check for Instrumented Kernel mode, type:

ls /proc/boot

If one of the files listed is procnto-*instr, you're successfully running the Instrumented Kernel. But if the file is procnto, you're running the noninstrumented kernel

To start the Instrumented Kernel, see the Tutorial chapter.

Run as root

The data-capture utilities require root privileges to allocate buffer memory or to use functions such as InterruptHookTrace() (see the Neutrino Library Reference). Data-capture utilities won't work properly without these privileges.

Monitor disk space

Because the tracelogger may write data at rates well in excess of 20 MB/min, running it for prolonged periods or running it repeatedly can use up a surprisingly large amount of space. If disk space is low, wipe old log files regularly. (In its default mode, tracelogger overwrites its previous default file.)