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

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Message-ID: <5799076a-7fbe-cba9-5c6a-73de83351a3a@gmail.com>
Date:   Sun, 20 Aug 2023 12:28:27 +0200
From:   Guillaume Martres <smarter3@...il.com>
To:     "Zhang, Rui" <rui.zhang@...el.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>
Cc:     "Bityutskiy, Artem" <artem.bityutskiy@...el.com>,
        "Kumar, Vinay" <vinay.kumar@...el.com>
Subject: Re: [PATCH] intel_idle: Add RaptorLake support



Le 20/08/2023 à 11:20, Zhang, Rui a écrit :
> On Sat, 2023-08-19 at 21:41 +0200, Guillaume Martres wrote:
>> On 1/19/23 17:13, Zhang, Rui wrote:
>>> On Thu, 2023-01-19 at 08:02 +0100, Álvaro Fernández Rojas wrote:
>>>> This patch adds RaptorLake support to the intel_idle driver.
>>>>
>>>> Since RaptorLake and AlderLake C-state are characteristics the
>>>> same,
>>>> we use
>>>> AlderLake C-states tables for RaptorLake as well.
>>>
>>> RPL and ADL have same cstates and use the same mwait hints, but the
>>> latency of each c-state are still different on different platforms.
>>> So we can not just duplicate the ADL table on RPL.
>>>
>>> There is an effort ongoing that measures the latency of each
>>> cstate on the RPL platforms. And based on the measurement result,
>>> we
>>> can decide if a new custom table is needed or we can just copy the
>>> previous platform. Hopefully we will have a patch in a couple of
>>> weeks.
>>
>> Hi, I just stumbled upon this patch series as I was wondering about
>> the
>> lack of support for Raptor Lake in intel_idle.
> 
> intel_idle support for RaptorLake, and also other platforms that don't
> have a custom table, is always there as long as we have BIOS support.
> The custom table is just an optimization.

Thanks for the information, I might be misinterpreting the effect of
this patch then. I can report that on a Thinkpad P1 Gen 6 using a stock
6.4.11 kernel, the list of C-states looks like this:

$ cat /sys/devices/system/cpu/cpu0/cpuidle/state*/name
POLL
C1_ACPI
C2_ACPI
C3_ACPI

Whereas with this patch they look like this:

$ cat /sys/devices/system/cpu/cpu0/cpuidle/state*/name
POLL
C1E
C6
C8
C10

Neither of which looks quite complete (and
/sys/module/intel_idle/parameters/max_cstate is set to 9). Is this
something I should open a bug report about?

Thanks,
Guillaume