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

[Sumit Garg]

On Mon, 18 May 2020 at 19:49, Mark Rutland <mark.rutland@xxxxxxx> wrote:
>
> On Mon, May 18, 2020 at 07:39:23PM +0530, Sumit Garg wrote:
> > On Mon, 18 May 2020 at 16:47, Alexandru Elisei <alexandru.elisei@xxxxxxx> wrote:
> > > On 5/18/20 11:45 AM, Mark Rutland wrote:
> > > > On Mon, May 18, 2020 at 02:26:00PM +0800, Lecopzer Chen wrote:
> > > >> HI Sumit,
> > > >>
> > > >> Thanks for your information.
> > > >>
> > > >> I've already implemented IPI (same as you did [1], little difference
> > > >> in detail), hardlockup detector and perf in last year(2019) for
> > > >> debuggability.
> > > >> And now we tend to upstream to reduce kernel maintaining effort.
> > > >> I'm glad if someone in ARM can do this work :)
> > > >>
> > > >> Hi Julien,
> > > >>
> > > >> Does any Arm maintainers can proceed this action?
> > > > Alexandru (Cc'd) has been rebasing and reworking Julien's patches, which
> > > > is my preferred approach.
> > > >
> > > > I understand that's not quite ready for posting since he's investigating
> > > > some of the nastier subtleties (e.g. mutual exclusion with the NMI), but
> > > > maybe we can put the work-in-progress patches somewhere in the mean
> > > > time.
> > > >
> > > > Alexandru, do you have an idea of what needs to be done, and/or when you
> > > > expect you could post that?
> > >
> > > I'm currently working on rebasing the patches on top of 5.7-rc5, when I have
> > > something usable I'll post a link (should be a couple of days). After that I will
> > > address the review comments, and I plan to do a thorough testing because I'm not
> > > 100% confident that some of the assumptions around the locks that were removed are
> > > correct. My guess is this will take a few weeks.
> > >
> >
> > Thanks Mark, Alex for the status updates on perf NMI feature.
> >
> > Alex,
> >
> > As the hard-lockup detection patch [1] has a dependency on perf NMI
> > patch-set, I will rebase and test hard-lockup detector when you have
> > got a working tree. But due to the dependency, I think patch [1]
> > should be accepted along with perf NMI patch-set. So would you be open
> > to include this patch as part of your series?
> >
> > [1] http://lists.infradead.org/pipermail/linux-arm-kernel/2020-May/732227.html
>
> While it depends on the perf NMI bits, I don't think it makes sense to
> tie that into the series given it's trying to achieve something very
> different.
>
> I think that should be reposted separately once the perf NMI bits are in
> shape.

Okay, fair enough. Will keep it as a separate patch then.

-Sumit

>
> Thanks,
> Mark.