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  1. RHEL
  2. RHEL-17203

On AMD Zenv3 (MilanX) server, kernel sometimes switches to hpet clocksource

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      Hello,

       

      on AMD Zenv3 (MilanX) server, kernel sometimes switches to the hpet clocksource.

       

      It happens rarely - in one of ~20 runs. Detected on these kernels:

      RHEL-9.3.0-20230521.45/kernel-5.14.0-316.el9.x86_64
      RHEL-9.3.0-20230718.0/kernel-5.14.0-339.el9.x86_64
      RHEL-8.10.0-20231115.3/kernel-4.18.0-521.el8.x86_64

      When it happens, we see it during the boot and during each reboot:

      $grep -n "clocksource: Switched to clocksource hpet" * 
      J:8572120_console.log-amd-epyc3-milanx-7573x-2s.lab.eng.brq2.redhat.com:1189:[    4.148100] clocksource: Switched to clocksource hpet  
      J:8572120_console.log-amd-epyc3-milanx-7573x-2s.lab.eng.brq2.redhat.com:8257:[    4.201239] clocksource: Switched to clocksource hpet  
      J:8572120_console.log-amd-epyc3-milanx-7573x-2s.lab.eng.brq2.redhat.com:11547:[    4.202106] clocksource: Switched to clocksource hpet  
      J:8572120_console.log-amd-epyc3-milanx-7573x-2s.lab.eng.brq2.redhat.com:14855:[    4.198264] clocksource: Switched to clocksource hpet  
      J:8572120_console.log-amd-epyc3-milanx-7573x-2s.lab.eng.brq2.redhat.com:26242:[    4.243240] clocksource: Switched to clocksource hpet

       

      Here are the corresponding messages from the console. log

       

      $grep clocksource J:8572120_console.log-amd-epyc3-milanx-7573x-2s.lab.eng.brq2.redhat.com 
      [    0.000000] clocksource: refined-jiffies: mask: 0xffffffff max_cycles: 0xffffffff, max_idle_ns: 1910969940391419 ns  
      [    0.001000] clocksource: hpet: mask: 0xffffffff max_cycles: 0xffffffff, max_idle_ns: 133484873504 ns  
      [    0.013006] clocksource: tsc-early: mask: 0xffffffffffffffff max_cycles: 0x285ceab5c76, max_idle_ns: 440795288513 ns  
      [    0.575283] clocksource: jiffies: mask: 0xffffffff max_cycles: 0xffffffff, max_idle_ns: 1911260446275000 ns  
      [    4.148100] clocksource: Switched to clocksource hpet  
      [    4.395941] clocksource: acpi_pm: mask: 0xffffff max_cycles: 0xffffff, max_idle_ns: 2085701024 ns

       

      Could you please have a look at why it's happening? 

       

      Thanks a lot

      Jirka

       

       

       

       

              jhladky1@redhat.com Jiri Hladky
              jhladky1@redhat.com Jiri Hladky
              Waiman Long
              Arch HW x86 Triage Bot Arch HW x86 Triage Bot
              William Gomeringer William Gomeringer
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                Created:
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