[PATCH][SRU][OEM-5.14] Improve performance and idle power consumption for AMD CPUs

[Alex Hung]

  BugLink: https://bugs.launchpad.net/bugs/1941893

[Impact]

  This can improve AMD performance for all Zen or newer CPU which support C3 shares cache.
  
[Fix]

  Its not necessary to flush the caches in software before entering C3.

  Empirical measurements show:
   40-45% improvement in speedometer score.
   ~15% improvement in idle power.

  The patch is in linux-next (tag next-20211007) and can be found @ https://git.kernel.org/pub/scm/linux/kernel/git/next/linux-next.git/commit/arch/x86/kernel/acpi/cstate.c?id=a8fb40966f19ff81520d9ccf8f7e2b95201368b8

[Test]

  This is requested by AMD.

[Where problems could occur]

  Low risk. This only works on AMD Zen CPUs that supports this features. AMD
  tested it and provided estimated measurement results.

Deepak Sharma (1):
  x86: ACPI: cstate: Optimize C3 entry on AMD CPUs

 arch/x86/kernel/acpi/cstate.c | 15 +++++++++++++++
 1 file changed, 15 insertions(+)

-- 
2.7.4