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  1. OpenShift Bugs
  2. OCPBUGS-17635

Random numbers in pids.max file on pods as well as on nodes.

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      Description of problem:
      In 4.12 OCP cluster the default podPidsLimit is 4096 when checked at node level in /sys/fs/cgroup/pids/kubepods.slice/kubepods-//pids.max path. 

      for f in /sys/fs/cgroup/pids/kubepods.slice/kubepods-*/*/pids.max; do echo $f.; cat $f; done
/sys/fs/cgroup/pids/kubepods.slice/kubepods-besteffort.slice/kubepods-besteffort-podb910bab7_528b_48c1_a0d5_72493eea2e0d.slice/pids.max.
4096
/sys/fs/cgroup/pids/kubepods.slice/kubepods-burstable.slice/kubepods-burstable-pod08371dcf_fcf7_49e7_84ef_d3887fcc7694.slice/pids.max.
4096
/sys/fs/cgroup/pids/kubepods.slice/kubepods-burstable.slice/kubepods-burstable-pod10795289d34b5e76d3845007b0111048.slice/pids.max.
4096
/sys/fs/cgroup/pids/kubepods.slice/kubepods-burstable.slice/kubepods-burstable-pod188fca37_2aef_4668_8f5d_c2a390e86cc6.slice/pids.max.
4096
/sys/fs/cgroup/pids/kubepods.slice/kubepods-burstable.slice/kubepods-burstable-pod2a47340c_46ef_41aa_94ce_10bc726ab328.slice/pids.max.
4096
/sys/fs/cgroup/pids/kubepods.slice/kubepods-burstable.slice/kubepods-burstable-pod3c0e1a64_46bc_41f9_9adf_b73157d7ae86.slice/pids.max.
4096
/sys/fs/cgroup/pids/kubepods.slice/kubepods-burstable.slice/kubepods-burstable-pod3e77ad6b_6fdc_4936_8054_14be023f26d8.slice/pids.max.
4096

      However , when we check inside any pod or node we could see a pids.max file with a random number . See section [A] and [B]

      • *[A] * pids.max inside container(having random number)
      [root@mirrorreg1 ~]# oc rsh <podname>
sh-4.4$ cat /sys/fs/cgroup/pids/pids.max
1288812
      • [B] pids.max inside node(having random number)
      cat /sys/fs/cgroup/pids/kubepods.slice/pids.max 
127385

      Can someone please help me to understand :

      • why we have three pids.max value on the cluster and which one should we consider for pod pid limit?
      • If the default podPidsLimit is 4096 why we see two other pids.max file with a random number inside pod?
      Version-Release number of selected component (if applicable):{code:none}

      How reproducible:

      On node:

      1. Login to ocp node
      2. check path /sys/fs/cgroup/pids/kubepods.slice/pids.max 

      
On pod

      1. Login to any pod
      2. Check path cat /sys/fs/cgroup/pids/pids.max

      Actual results:{code:none}

      Expected results:

      Pod pids limit can only be seen /sys/fs/cgroup/pids/kubepods.slice/kubepods-*/*/pids.max

      Additional info:

      This behavior can be seen in any OCP cluster. Do let me know if you need any logs.

              pehunt@redhat.com Peter Hunt
              rhn-support-psingour Poornima Singour
              Aditi Sahay Aditi Sahay
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                Created:
                Updated:
                Resolved: