High volume of calls to _spin_unlock_irqrestore causing high CPU usage

Solution Unverified - Updated -

Issue

  • A system is reporting high CPU usage on an application.
  • "perf" output shows that _spin_unlock_irqrestore is consuming 20% of the processing time.
  • top and ps show a large percentage of time spent in %sys for a process.

Environment

  • Red Hat Enterprise Linux 6 - x86 and x86-64 architecture.
  • VMWare ESX 5.0.x or earlier.
  • Performance monitoring tools using hardware counters (oprofile or perf)

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