Setting the Processor Frequency for Intel® Cluster Checker Performance Tests

Note: This article is only applicable to clusters on which Enhanced Intel Speedstep® Technology is enabled.

Enhanced Intel Speedstep Technology allows systems to achieve very high performance while also conserving power. However, clusters using Enhanced Intel Speedstep Technology may experience intermittent performance failures when checked with Intel Cluster Checker.  Due to the ability of the cluster nodes to dynamically adjust processor frequency, performance results may be lower than expected.  This issue affects nearly all the checks that verify cluster performance, including mflops_intel_mkl, hpcc, and imb_pingpong_intel_mpi.

The recommended method to resolve this issue, without disabling Enhanced Intel Speedstep Technology, is to manually set the processor frequency on all cluster nodes.  Processor frequency should be statically configured until Intel Cluster Checker execution is complete. Most versions of Linux provide utilities to control dynamic processor frequency. Two common utilities are cpuspeed and powersaved.

Follow the following steps:
  1. Manually set all processors in the cluster to maximum frequency. This is normally done executing the CPU frequency scaling utility with the correct options. The command must be executed on all nodes using the cluster-wide execution capability required by Intel Cluster Ready.
  2. Run Intel Cluster Checker.
  3. Once Intel Cluster Checker has completed successfully, restore dynamic CPU frequency scaling on all nodes.
For example, to set maximum processor frequency on a cluster using cpuspeed and pdsh:
pdsh –a "killall -SIGUSR1 cpuspeed"

To return the processor frequency scaling to automatic mode:
pdsh –a "killall -SIGHUP cpuspeed"

With the introduction of Intel® Turbo Boost Technology in Intel Core™ i7 processors, processor frequency can exceed the base operating frequency.  Additional steps may be required to force the processors to run at nominal base frequency, instead of maximum frequency.

More information on Enhanced Intel Speedstep Technology can be found at

The following article discusses how to implement processor frequency control for high performance computing clusters:
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