Re: [Bug 217321] New: Intel platforms can't sleep deeper than PC3 during long idle

["Linux regression tracking #adding (Thorsten Leemhuis)" <regressions@leemhuis.info>]

A quick note before the usual boilerplate:

Bjorn, you asked KobaKo some questions, but didn't CC him -- and the
comment apparently did not make it to the bugzilla ticket. Something
wrong there? I wish I could CC him, but due to bugzilla's "never show
your email address to logged out users" policies I can't. I added a
comment to the ticket pointing him to your mail.

[TLDR for the rest of the mail: adding this reported to the regression
tracking]

[CCing the regression list, as it should be in the loop for regressions:
https://docs.kernel.org/admin-guide/reporting-regressions.html]

On 11.04.23 22:42, Bjorn Helgaas wrote:
> On Tue, Apr 11, 2023 at 08:32:04AM +0000, bugzilla-daemon@kernel.org wrote:
>> https://bugzilla.kernel.org/show_bug.cgi?id=217321
>> ... 
>>         Regression: No
>>
>> [Symptom]
>> Intel cpu can't sleep deeper than pcˇ during long idle
>> ~~~
>> Pkg%pc2 Pkg%pc3 Pkg%pc6 Pkg%pc7 Pkg%pc8 Pkg%pc9 Pk%pc10
>> 15.08   75.02   0.00    0.00    0.00    0.00    0.00
>> 15.09   75.02   0.00    0.00    0.00    0.00    0.00
>> ^CPkg%pc2       Pkg%pc3 Pkg%pc6 Pkg%pc7 Pkg%pc8 Pkg%pc9 Pk%pc10
>> 15.38   68.97   0.00    0.00    0.00    0.00    0.00
>> 15.38   68.96   0.00    0.00    0.00    0.00    0.00
>> ~~~
>> [How to Reproduce]
>> 1. run turbostat to monitor
>> 2. leave machine idle
>> 3. turbostat show cpu only go into pc2~pc3.
>>
>> [Misc]
>> The culprit are this 
>> a7152be79b62) Revert "PCI/ASPM: Save L1 PM Substates Capability for
>> suspend/resume”
>>
>> if revert a7152be79b62, the issue is gone
> 
> Relevant commits:
> 
>   4ff116d0d5fd ("PCI/ASPM: Save L1 PM Substates Capability for suspend/resume")
>   a7152be79b62 ("Revert "PCI/ASPM: Save L1 PM Substates Capability for suspend/resume"")
> 
> 4ff116d0d5fd appeared in v6.1-rc1.  Prior to 4ff116d0d5fd, ASPM L1 PM
> Substates configuration was not preserved across suspend/resume, so
> the system *worked* after resume, but used more power than expected.
> 
> But 4ff116d0d5fd caused resume to fail completely on some systems, so
> a7152be79b62 reverted it.  With a7152be79b62 reverted, ASPM L1 PM
> Substates configuration is likely not preserved across suspend/resume.
> a7152be79b62 appeared in v6.2-rc8 and was backported to the v6.1
> stable series starting with v6.1.12.
> 
> KobaKo, you don't mention any suspend/resume in this bug report, but
> neither patch should make any difference unless suspend/resume is
> involved.  Does the platform sleep as expected *before* suspend, but
> fail to sleep after resume?
> 
> Or maybe some individual device was suspended via runtime power
> management, and that device lost its L1 PM Substates config?  I don't
> know if there's a way to disable runtime PM easily.
> 
> The lspci output attached to the bugzilla was not collected as root,
> so it lacks the ASPM-related information.  Can you do this again with
> "sudo lspci -vv"?
#regzbot introduced: a7152be79b62
https://bugzilla.kernel.org/show_bug.cgi?id=217321
#regzbot title: PCI/ASPM: Intel system does not sleep deeper than PC3
(caused by a revert applied to fixes another regression)
#regzbot ignore-activity

Ciao, Thorsten (wearing his 'the Linux kernel's regression tracker' hat)
--
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