** Changed in: linux (Ubuntu)
     Assignee: (unassigned) => dann frazier (dannf)

** Changed in: linux (Ubuntu Xenial)
     Assignee: (unassigned) => dann frazier (dannf)

** Changed in: linux (Ubuntu Yakkety)
     Assignee: (unassigned) => dann frazier (dannf)

** Changed in: linux (Ubuntu Zesty)
     Assignee: (unassigned) => dann frazier (dannf)

** Description changed:

  [Impact]
  Performance is lowered for ARM >= v8.1 cpus by not taking advantage of the 
"Large System Extenstion" atomic instructions they provide.
  
  Note: This config was enabled during xenial development, but was
  disabled to workaround a FTBFS[*] due to us not having a new enough
  binutils to support it. binutils was later updated in xenial, and
  supports these instructions.
  
  [Test Case]
  TBD
  
  [Regression Risk]
  There is a known small performance overhead for <= ARMv8.1 arm64 systems 
(noted in the Kconfig).
  [...TBD...]
  
- 
- [*] 
https://launchpadlibrarian.net/229977996/buildlog_ubuntu-xenial-arm64.linux_4.4.0-0.5_BUILDING.txt.gz
+ [*] https://answers.launchpad.net/~canonical-kernel-
+ team/+archive/ubuntu/unstable/+build/8438034

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https://bugs.launchpad.net/bugs/1691614

Title:
  please enable CONFIG_ARM64_LSE_ATOMICS

Status in linux package in Ubuntu:
  Incomplete
Status in linux source package in Xenial:
  Incomplete
Status in linux source package in Yakkety:
  Incomplete
Status in linux source package in Zesty:
  Incomplete

Bug description:
  [Impact]
  Performance is lowered for ARM >= v8.1 cpus by not taking advantage of the 
"Large System Extenstion" atomic instructions they provide.

  Note: This config was enabled during xenial development, but was
  disabled to workaround a FTBFS[*] due to us not having a new enough
  binutils to support it. binutils was later updated in xenial, and
  supports these instructions.

  [Test Case]
  TBD

  [Regression Risk]
  There is a known small performance overhead for <= ARMv8.1 arm64 systems 
(noted in the Kconfig).
  [...TBD...]

  [*] https://answers.launchpad.net/~canonical-kernel-
  team/+archive/ubuntu/unstable/+build/8438034

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