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

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Message-Id: <BCBB0027-F0E9-42EE-BB43-D50091D9115F@gmail.com>
Date: Sun, 7 Apr 2024 19:37:19 +0200
From: László Péter <peter.laszlo2@...il.com>
To: "Zhang, Rui" <rui.zhang@...el.com>
Cc: "smarter3@...il.com" <smarter3@...il.com>,
 "linux-pm@...r.kernel.org" <linux-pm@...r.kernel.org>,
 "jacob.jun.pan@...ux.intel.com" <jacob.jun.pan@...ux.intel.com>,
 "noltari@...il.com" <noltari@...il.com>,
 "lenb@...nel.org" <lenb@...nel.org>,
 "linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
 "Bityutskiy, Artem" <artem.bityutskiy@...el.com>,
 "Kumar, Vinay" <vinay.kumar@...el.com>
Subject: Re: [PATCH] intel_idle: Add RaptorLake support

> On 20 Aug 2023, at 11:20, Zhang, Rui <rui.zhang@...el.com> wrote:
> 
> This is still work in progress because there are still some open
> questions that we cannot answer from our measurement, and the table is
> not finalized yet.
> 
> thanks,
> rui
> 
> 

Hi,

I also just stumbled upon this patch series as I was wondering about the lack of specific support for RaptorLake in intel_idle. The AlderLake specific part of the intel_idle.c code mentions that "On AlderLake C1 has to be disabled if C1E is enabled, and vice versa …. By default we enable C1E and disable C1 by marking it with...”.   Without a patch on RaptorLake (which I assume works the same way) this cannot be controlled with the preferred_cstates kernel parameter. Also on my NUC 13 Pro i5-1340P the latency for C10 looks suspiciously large compared to the AlderLake cstates table.

grep . /sys/devices/system/cpu/cpu0/cpuidle/state*/desc
/sys/devices/system/cpu/cpu0/cpuidle/state0/desc:CPUIDLE CORE POLL IDLE
/sys/devices/system/cpu/cpu0/cpuidle/state1/desc:ACPI FFH MWAIT 0x0
/sys/devices/system/cpu/cpu0/cpuidle/state2/desc:ACPI FFH MWAIT 0x21
/sys/devices/system/cpu/cpu0/cpuidle/state3/desc:ACPI FFH MWAIT 0x60

grep . /sys/devices/system/cpu/cpu0/cpuidle/state*/latency
/sys/devices/system/cpu/cpu0/cpuidle/state0/latency:0
/sys/devices/system/cpu/cpu0/cpuidle/state1/latency:1
/sys/devices/system/cpu/cpu0/cpuidle/state2/latency:127
/sys/devices/system/cpu/cpu0/cpuidle/state3/latency:1048

Thanks,
Peter