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S E N D S I G

I N T R O D U C T I O N

This module, maybe, is stupid. It does an easy task in a very complicated fashion. But it seems to work.

The need for such a module arises from a problem with a real time process; it sometimes reaches a share of cpu of 100% and no userspace strategy has shown to be useful in killing it automagically.

So the idea: writing a kernel module that, given a pid, is able to send a signal to it if a specific condition on the share of cpu used by the process is met.

The sendsig module will check every WAIT_TIMEOUT seconds if the process you want to monitor has a share of cpu greater than or equal to MAX_CPU_SHARE. If the process is in this situation for MAX_CHECK consecutive checks, sendsig will send a SIG_TO_SEND signal to it. Additionally, these parameters could be tuned up to fit everyone needs by setting them in the command line of the module, eg:

insmod sendsig max_cpu_share=60 wait_timeout=5 max_checks=5 sig_to_send=9

See "modinfo sendsig" for more details.

C O M P I L I N G

  • cd sendsig
  • make
  • make install (as root)

U S A G E

  • Load the module as you prefer
  • echo PID_YOU_WANT_TO_CHECK > DEBUGFS_MOUNTPOINT/sendsig
  • pray