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

Sudeep Holla
2018-05-30T13:24:59Z

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@arm.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@arm.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