Re: [PATCH] x86: Prefer MWAIT over HALT on AMD processors
From: Borislav Petkov
Date: Tue Apr 05 2022 - 17:39:07 EST
On Tue, Apr 05, 2022 at 06:30:21PM +0530, Wyes Karny wrote:
> From: Lewis Caroll <lewis.carroll@xxxxxxx>
> Currently in the absence of the cpuidle driver (eg: when global
> C-States are disabled in the BIOS or when cpuidle is driver is not
> compiled in),
When does that ever happen?
Sounds like a very very niche situation to me...
> Here we enable MWAIT instruction as the default idle call for AMD
> Zen processors which support MWAIT. We retain the existing behaviour
> for older processors which depend on HALT.
Please use passive voice in your commit message: no "we" or "I", etc,
and describe your changes in imperative mood.
Also, pls read section "2) Describe your changes" in
Documentation/process/submitting-patches.rst for more details.
Also, see section "Changelog" in
Bottom line is: personal pronouns are ambiguous in text, especially with
so many parties/companies/etc developing the kernel so let's avoid them
> static int prefer_mwait_c1_over_halt(const struct cpuinfo_x86 *c)
> - if (c->x86_vendor != X86_VENDOR_INTEL)
> + if (!early_mwait_supported(c))
Isn't it enough to simply do here:
if (cpu_has(c, X86_FEATURE_ZEN))
if (c->x86_vendor != X86_VENDOR_INTEL)