linux-kernel - Re: [PATCH v9 00/12] Support PPTT for ARM64

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Date:   Wed, 30 May 2018 14:24:42 +0100
From:   Sudeep Holla <sudeep.holla@....com>
To:     Jeremy Linton <jeremy.linton@....com>,
        Geert Uytterhoeven <geert@...ux-m68k.org>,
        Will Deacon <will.deacon@....com>
Cc:     Sudeep Holla <sudeep.holla@....com>,
        Catalin Marinas <catalin.marinas@....com>,
        ACPI Devel Maling List <linux-acpi@...r.kernel.org>,
        Mark Rutland <Mark.Rutland@....com>, austinwc@...eaurora.org,
        tnowicki@...iumnetworks.com, Palmer Dabbelt <palmer@...ive.com>,
        linux-riscv@...ts.infradead.org, Morten.Rasmussen@....com,
        vkilari@...eaurora.org,
        Lorenzo Pieralisi <Lorenzo.Pieralisi@....com>,
        jhugo@...eaurora.org, Al Stone <ahs3@...hat.com>,
        Len Brown <lenb@...nel.org>,
        John Garry <john.garry@...wei.com>, wangxiongfeng2@...wei.com,
        Dietmar Eggemann <Dietmar.Eggemann@....com>,
        Linux ARM <linux-arm-kernel@...ts.infradead.org>,
        Ard Biesheuvel <ard.biesheuvel@...aro.org>,
        Greg KH <gregkh@...uxfoundation.org>,
        "Rafael J. Wysocki" <rjw@...ysocki.net>,
        Linux Kernel Mailing List <linux-kernel@...r.kernel.org>,
        Hanjun Guo <hanjun.guo@...aro.org>,
        Linux-Renesas <linux-renesas-soc@...r.kernel.org>
Subject: Re: [PATCH v9 00/12] Support PPTT for ARM64



On 29/05/18 22:52, Jeremy Linton wrote:
> Hi,
> 
> On 05/29/2018 10:51 AM, Geert Uytterhoeven wrote:
>> Hi Will,
>>
>> On Tue, May 29, 2018 at 5:08 PM, Will Deacon <will.deacon@....com> wrote:
>>> On Tue, May 29, 2018 at 02:18:40PM +0100, Sudeep Holla wrote:
>>>> On 29/05/18 12:56, Geert Uytterhoeven wrote:
>>>>> On Tue, May 29, 2018 at 1:14 PM, Sudeep Holla
>>>>> <sudeep.holla@....com> wrote:
>>>>>> On 29/05/18 11:48, Geert Uytterhoeven wrote:
>>>>>>> System supend still works fine on systems with big cores only:
>>>>>>>
>>>>>>>      R-Car H3 ES1.0 (4xCA57 (4xCA53 disabled in firmware))
>>>>>>>      R-Car M3-N (2xCA57)
>>>>>>>
>>>>>>> Reverting this commit fixes the issue for me.
>>>>>>
>>>>>> I can't find anything that relates to system suspend in these patches
>>>>>> unless they are messing with something during CPU hot plug-in back
>>>>>> during resume.
>>>>>
>>>>> It's only the last patch that introduces the breakage.
>>>>>
>>>>
>>>> As specified in the commit log, it won't change any behavior for DT
>>>> systems if it's non-NUMA or single node system. So I am still wondering
>>>> what could trigger this regression.
>>>
>>> I wonder if we're somehow giving an uninitialised/invalid NUMA
>>> configuration
>>> to the scheduler, although I can't see how this would happen.
>>>
>>> Geert -- if you enable CONFIG_DEBUG_PER_CPU_MAPS=y and apply the diff
>>> below
>>> do you see anything shouting in dmesg?
>>
>> Thanks, but unfortunately it doesn't help.
>> I added some debug code to print cpumask, but so far I don't see anything
>> suspicious.
> 
> I suspect most of the problem is related to the node mask changing at
> unexpected times (particularly cores being removed from the mask). Once
> I understand that more, there may be a simpler patch.
> 
> OTOH, I've been testing with this, and with it, I can't seem to
> duplicate the problem with CONFIG_NUMA disabled I found.
> 

I am also giving it a run on my Juno(defconfig - CONFIG_NUMA) and CPU
hotplug tests are fine with this change.

-- 
Regards,
Sudeep