linux-kernel - Re: [PATCH v2 0/6] arm64: provide pseudo NMI with GICv3

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Message-ID: <07a0b8c1-3d87-0cae-61df-dbff782be301@arm.com>
Date:   Mon, 30 Apr 2018 10:53:17 +0100
From:   Julien Thierry <julien.thierry@....com>
To:     Joel Fernandes <joel.opensrc@...il.com>
Cc:     Linux ARM Kernel List <linux-arm-kernel@...ts.infradead.org>,
        Linux Kernel Mailing List <linux-kernel@...r.kernel.org>,
        mark.rutland@....com, marc.zyngier@....com, james.morse@....com,
        daniel.thompson@...aro.org, Joel Fernandes <joelaf@...gle.com>
Subject: Re: [PATCH v2 0/6] arm64: provide pseudo NMI with GICv3



On 29/04/18 07:37, Joel Fernandes wrote:
> On Wed, Jan 17, 2018 at 4:10 AM, Julien Thierry <julien.thierry@....com> wrote:
>> Hi,
>>
>> On 17/01/18 11:54, Julien Thierry wrote:
>>>
>>> This series is a continuation of the work started by Daniel [1]. The goal
>>> is to use GICv3 interrupt priorities to simulate an NMI.
>>>
>>
>>
>> I have submitted a separate series making use of this feature for the ARM
>> PMUv3 interrupt [1].
> 
> I guess the hard lockup detector using NMI could be a nice next step
> to see how well it works with lock up detection. That's the main
> usecase for my interest. However, perf profiling is also a strong one.
> 

 From my understanding, Linux's hardlockup detector already uses the ARM 
PMU interrupt to check whether some task is stuck. I haven't looked at 
the details of the implementation yet, but in theory having the PMU 
interrupt as NMI should make the hard lockup detector use the NMI.

When I do the v3, I'll have a look at this to check whether the 
hardlockup detector works fine when using NMI.

Cheers,

-- 
Julien Thierry