Article ID: 118692, created on Nov 17, 2013, last review on May 10, 2014

  • Applies to:
  • Virtuozzo 6.0
  • Virtuozzo containers for Linux
  • Virtuozzo hypervisor

Symptoms

While running a CPU stress test inside a container with a script that keeps all CPUs 100% busy, monitoring utilities like htop show only half of the CPUs loaded. This is an example for a 8-core container:

  • run stress tool inside the container:

    # stress --cpu 8
    stress: info: [7919] dispatching hogs: 8 cpu, 0 io, 0 vm, 0 hdd
    
  • htop shows half of the CPUs under load:

      1  [                                                          0.0%]
      2  [|||||||||||||||||||||||||||||||||||||||||||||||||        78.4%]
      3  [                                                          0.0%]
      4  [|||||||||||||||||||||||||||||||||||||||||||||||||||||||  88.0%]
      5  [                                                          0.0%]
      6  [|||||||||||||||||||||||||||||||||||||||||||||||||||||||||97.4%]
      7  [                                                          0.0%]
      8  [|||||||||||||||||||||||||||||||||||||||||||||||||||||||||97.1%]
      Mem[||                                                 128/49152MB]
      Swp[                                                      0/4000MB]
    
    
     PID USER     PRI  NI  VIRT   RES   SHR S CPU% MEM%   TIME+  Command
     7926 root      20   0  6308   204   108 R 80.0  0.0  0:09.66 stress --cpu 8
     7924 root      20   0  6308   204   108 R 72.0  0.0  0:09.31 stress --cpu 8
     7921 root      20   0  6308   204   108 R 71.0  0.0  0:10.84 stress --cpu 8
     7923 root      20   0  6308   204   108 R 64.0  0.0  0:08.47 stress --cpu 8
     7925 root      20   0  6308   204   108 R 61.0  0.0  0:09.96 stress --cpu 8
     7920 root      20   0  6308   204   108 R 58.0  0.0  0:09.43 stress --cpu 8
     7922 root      20   0  6308   204   108 R 57.0  0.0  0:09.34 stress --cpu 8
     7927 root      20   0  6308   204   108 R 54.0  0.0  0:07.87 stress --cpu 8
    

However if we check this from the node all 8 cores will be shown under the load.

Cause

The issue is recognized as product bug with internal ID PSBM-23431.

Resolution

To be fixed in one of future kernel updates.

Search Words

stress

half

htop

CPU load

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