linux-kernel - Re: [PATCH HACK RFC] cpu: Prevent late-arriving interrupts from disrupting offline

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Message-ID: <89ba6366-5be3-736e-ee78-3d9510aa2576@arm.com>
Date:   Tue, 11 Jun 2019 16:39:34 +0200
From:   Dietmar Eggemann <dietmar.eggemann@....com>
To:     paulmck@...ux.ibm.com
Cc:     Mark Rutland <mark.rutland@....com>,
        Peter Zijlstra <peterz@...radead.org>, tglx@...utronix.de,
        mingo@...nel.org, jpoimboe@...hat.com, mojha@...eaurora.org,
        linux-kernel@...r.kernel.org
Subject: Re: [PATCH HACK RFC] cpu: Prevent late-arriving interrupts from
 disrupting offline

On 6/11/19 3:54 PM, Paul E. McKenney wrote:
> On Tue, Jun 11, 2019 at 03:14:54PM +0200, Dietmar Eggemann wrote:
>> On 6/8/19 6:41 PM, Paul E. McKenney wrote:
>>> On Tue, Jun 04, 2019 at 03:29:32PM +0200, Dietmar Eggemann wrote:
>>>> On 6/4/19 9:45 AM, Paul E. McKenney wrote:
>>>>> On Mon, Jun 03, 2019 at 03:39:18PM +0200, Dietmar Eggemann wrote:
>>>>>> On 6/3/19 1:44 PM, Mark Rutland wrote:
>>>>>>> On Mon, Jun 03, 2019 at 10:38:48AM +0200, Peter Zijlstra wrote:
>>>>>>>> On Sat, Jun 01, 2019 at 06:12:53PM -0700, Paul E. McKenney wrote:
>>>>>>>>> Scheduling-clock interrupts can arrive late in the CPU-offline process,

[...]

>> Tested your patch on top of v5.2-rc4* on Arm TC2 (32bit) and CPU
>> hotplug stress test. W/o your patch, the test fails within seconds
>> since CPUs are not coming up again. W/ your patch, the test runs for
>> hours just fine.
>>
>> You can add my:
>>
>> Tested-by: Dietmar Eggemann <dietmar.eggemann@....com>
> 
> Thank you!!!
> 
>> * just for the record: one additional unrelated patch (to disable
>> the NOR flash) is necessary on Arm TC2:
>> https://patchwork.kernel.org/patch/10968391 .
> 
> Is this progressing, or does it also need help getting to mainline?

This is an unrelated specific issue w/ the TC2 platform which will 
progress independently. Other Arm32 platforms should profit from your 
patch independently of that. I just wanted to mention it here in case 
people try to recreate the test on this specific platform.
> Left to myself, I will push my patch and assume that the NOR flash patch
> will make it in its own good time -- or, alternatively, that there is
> someone better positioned than me to push it.

IMHO, the best thing is you push your patch.