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[Portia Stephens <1992912@xxxxxxxxxxxxxxxxxx>]

** Changed in: linux-xilinx-zynqmp (Ubuntu)
       Status: New => Fix Released

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https://bugs.launchpad.net/bugs/1992912

Title:
  linux-xilinx-zynqmp/focal: main(): sched_setscheduler(): Operation not
  permitted

Status in ubuntu-kernel-tests:
  New
Status in linux-xilinx-zynqmp package in Ubuntu:
  Fix Released
Status in linux-xilinx-zynqmp source package in Focal:
  Fix Committed

Bug description:
  [SRU Justification]

  [Impact]
  The focal kernel is failing the ubuntu_ltp:sched:time-schedule01, ubuntu_ltp:sched:trace_sched01 and ubuntu_ltp:irq:irqbalance0 regression test due to sched_setscheduler being unable to a task class to SCHED_FIFO. This is due to have having CONFIG_RT_GROUP_SCHED enabled. Once RT_GROUP_SCHED is enabled it is impossible to schedule realtime tasks for non-root users until you allocate realtime bandwidth for them. 

  There are multiple known issues with CONFIG_RT_GROUP_SCHED that are reported in the debian.master/config/annotations file:
  https://bugs.launchpad.net/ubuntu/+source/linux/+bug/1284731
  https://bugs.launchpad.net/ubuntu/+source/linux/+bug/1873315
  https://bugs.launchpad.net/ubuntu/+source/linux/+bug/1875665

  [Fix]

  CONFIG_RT_GROUP_SCHED should be disabled. The config was enabled when
  we copied the Xilinx default config settings and there is not a
  justification for this exact config. There may even be a negative
  impact, from the kernel.org documentation:

  “The default values for sched_rt_period_us (1000000 or 1s) and
  sched_rt_runtime_us (950000 or 0.95s). This gives 0.05s to be used by
  SCHED_OTHER (non-RT tasks).”

  This suggests this option will benefit RT systems, but be detrimental
  to non-RT systems,

  [Testcase]

  The annotations file will enforce that CONFIG_RT_GROUP_SCHED is
  disabled.

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