linux-kernel - Re: [PATCH] intel_idle: Add ICL support

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Message-ID: <72fab2376722c6169549669016933217d3da34a0.camel@gmail.com>
Date:   Wed, 26 Aug 2020 19:19:35 +0300
From:   Artem Bityutskiy <dedekind1@...il.com>
To:     Guilhem Lettron <guilhem@...pilot.io>,
        Zhang Rui <rui.zhang@...el.com>
Cc:     "Rafael J. Wysocki" <rafael@...nel.org>,
        Jacob Pan <jacob.jun.pan@...ux.intel.com>,
        Len Brown <lenb@...nel.org>,
        Linux PM <linux-pm@...r.kernel.org>,
        Linux Kernel Mailing List <linux-kernel@...r.kernel.org>
Subject: Re: [PATCH] intel_idle: Add ICL support

Indeed, when I compare them:

acpi_idle (without the patch):

CPU%c1  CPU%c6  CPU%c7  CoreTmp PkgTmp  GFX%rc6 Pkg%pc2 Pkg%pc3 Pkg%pc6 Pkg%pc7 Pkg%pc8 Pkg%pc9 Pk%pc10 PkgWatt
29.48   0.00    60.71   58      58      97.96   16.96   0.00    0.00    0.00    0.00    0.00    0.00    6.08

intel_idle (with the patch):

CPU%c1  CPU%c6  CPU%c7  CoreTmp PkgTmp  GFX%rc6 Pkg%pc2 Pkg%pc3 Pkg%pc6 Pkg%pc7 Pkg%pc8 Pkg%pc9 Pk%pc10 PkgWatt
56      56      96.64   300     68.29   48.58   0.00    0.00    0.00    0.00    0.00    0.00    7.38    0.00

With intel_idle we reach PC10, without it we only go as deep as PC2 - huge difference.

I really wonder why the BIOS does not expose deeper C-states... And if
it does not, is this for a reason? And how windows works then?

May be there is a BIOS update that fixes this problem? May be Windows
user get it quickly because stuff like this is often well-integrated in
Windows? Would you please check if there is newer BIOS?

Artem.