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

Timo Aaltonen tjaalton at ubuntu.com
Mon Oct 25 15:36:39 UTC 2021


On 9.10.2021 5.07, Alex Hung wrote:
>    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(+)
> 

applied to oem-5.14, thanks


-- 
t



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