Re: [PATCH 0/3] arm64: perf: Add support for Perf NMI interrupts

[Sumit Garg]

+ Julien

Hi Lecopzer,

On Sat, 16 May 2020 at 18:20, Lecopzer Chen <lecopzer@xxxxxxxxx> wrote:
>
> These series implement Perf NMI funxtionality and depends on
> Pseudo NMI [1] which has been upstreamed.
>
> In arm64 with GICv3, Pseudo NMI was implemented for NMI-like interruts.
> That can be extended to Perf NMI which is the prerequisite for hard-lockup
> detector which had already a standard interface inside Linux.
>
> Thus the first step we need to implement perf NMI interface and make sure
> it works fine.
>

This is something that is already implemented via Julien's patch-set
[1]. Its v4 has been floating since July, 2019 and I couldn't find any
major blocking comments but not sure why things haven't progressed
further.

Maybe Julien or Arm maintainers can provide updates on existing
patch-set [1] and how we should proceed further with this interesting
feature.

And regarding hard-lockup detection, I have been able to enable it
based on perf NMI events using Julien's perf patch-set [1]. Have a
look at the patch here [2].

[1] https://patchwork.kernel.org/cover/11047407/
[2] http://lists.infradead.org/pipermail/linux-arm-kernel/2020-May/732227.html

-Sumit

> Perf NMI has been test by dd if=/dev/urandom of=/dev/null like the link [2]
> did.
>
> [1] https://lkml.org/lkml/2019/1/31/535
> [2] https://www.linaro.org/blog/debugging-arm-kernels-using-nmifiq
>
>
> Lecopzer Chen (3):
>   arm_pmu: Add support for perf NMI interrupts registration
>   arm64: perf: Support NMI context for perf event ISR
>   arm64: Kconfig: Add support for the Perf NMI
>
>  arch/arm64/Kconfig             | 10 +++++++
>  arch/arm64/kernel/perf_event.c | 36 ++++++++++++++++++------
>  drivers/perf/arm_pmu.c         | 51 ++++++++++++++++++++++++++++++----
>  include/linux/perf/arm_pmu.h   |  6 ++++
>  4 files changed, 88 insertions(+), 15 deletions(-)
>
> --
> 2.25.1
>
>
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