This bug is awaiting verification that the linux-lowlatency-
hwe-5.19/5.19.0-1017.18~22.04.1 kernel in -proposed solves the problem.
Please test the kernel and update this bug with the results. If the
problem is solved, change the tag 'verification-needed-jammy' to
'verification-done-jammy'. If the problem still exists, change the tag
'verification-needed-jammy' to 'verification-failed-jammy'.

If verification is not done by 5 working days from today, this fix will
be dropped from the source code, and this bug will be closed.

See for documentation how
to enable and use -proposed. Thank you!

** Tags added: kernel-spammed-jammy-linux-lowlatency-hwe-5.19

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  ACPI: processor idle: Practically limit "Dummy wait" workaround to old
  Intel systems

Status in linux package in Ubuntu:
  In Progress
Status in linux source package in Bionic:
  Fix Released
Status in linux source package in Focal:
  Fix Released
Status in linux source package in Jammy:
  Fix Released
Status in linux source package in Kinetic:
  Fix Released

Bug description:
  Old, circa 2002 chipsets have a bug: they don't go idle when they are
  supposed to.  So, a workaround was added to slow the CPU down and
  ensure that the CPU waits a bit for the chipset to actually go idle.
  This workaround is ancient and has been in place in some form since
  the original kernel ACPI implementation.

  But, this workaround is very painful on modern systems.  The "inl()"
  can take thousands of cycles (see Link: for some more detailed
  numbers and some fun kernel archaeology).

  First and foremost, modern systems should not be using this code.
  Typical Intel systems have not used it in over a decade because it is
  horribly inferior to MWAIT-based idle.

  Despite this, people do seem to be tripping over this workaround on
  AMD system today.

  Limit the "dummy wait" workaround to Intel systems.  Keep Modern AMD
  systems from tripping over the workaround.  Remotely modern Intel
  systems use intel_idle instead of this code and will, in practice,
  remain unaffected by the dummy wait.

  Reported-by: K Prateek Nayak <>
  Suggested-by: Rafael J. Wysocki <>
  Signed-off-by: Dave Hansen <>
  Reviewed-by: Mario Limonciello <>
  Tested-by: K Prateek Nayak <>


  This issue pertains to  all Zen based processors starting with
  Naples(Zen1). All LTS releases will need this fix:


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