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

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Message-Id: <20190608164158.GK28207@linux.ibm.com>
Date:   Sat, 8 Jun 2019 09:41:58 -0700
From:   "Paul E. McKenney" <paulmck@...ux.ibm.com>
To:     Dietmar Eggemann <dietmar.eggemann@....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 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,
> 
> [...]
> 
> >>>   05981277a4de1ad6 ("arm64: Use common outgoing-CPU-notification code")
> >>>
> >>>... but it looks like Paul's patch to do so [1] fell through the cracks;
> >>>I'm not aware of any reason that shouldn't have been taken.
> >>>[1] https://lore.kernel.org/lkml/1431467407-1223-8-git-send-email-paulmck@linux.vnet.ibm.com/
> >>>
> >>>Paul, do you want to resend that?
> >>
> >>Please do. We're carrying this patch out-of-tree for while now in
> >>our EAS integration to get cpu hotplug tests passing on TC2 (arm).
> >
> >Huh.  It still applies.  But I have no means of testing it.
> 
> We can do the testing part on our TC2 platform, i.e. we're testing
> it with each of our EAS mainline integration right now.
> 
> https://developer.arm.com/tools-and-software/open-source-software/linux-kernel/energy-aware-scheduling/eas-mainline-development
> 
> http://linux-arm.org/git?p=linux-power.git;a=commit;h=8cd16f1dc2cd896a0b1e2010b4992b33fdc11fe0
> 
> >And it looks like the reason I dropped it was that I didn't get any
> >response from the maintainer.  I sent a message to this effect to
> >linux-arm-kernel@...ts.infradead.org and linux@....linux.org.uk on May
> >21, 2015.
> >
> >So here it is again.  ;-)
> >
> >I have queued this locally.  Left to myself, I add the two of you on its
> >Cc: list and run it through my normal process.  But given the history,
> >I would still want either an ack from the maintainer or, better, for
> >the maintainer to take the patch.
> >
> >Or is there a better way for us to proceed on this?
> 
> You could send this patch also to
> linux-arm-kernel@...ts.infradead.org and cc rmk to get his opinion
> on the patch.

OK, please let me know how the testing goes.  My thought is to send the
patch as you suggest with your Tested-by.

							Thanx, Paul