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From: Marc Zyngier <maz@kernel.org>
To: Valentin Schneider <valentin.schneider@arm.com>,
	Vladimir Oltean <olteanv@gmail.com>
Cc: paulmck@kernel.org, Robin Murphy <robin.murphy@arm.com>,
	Alison Wang <alison.wang@nxp.com>,
	linux-kernel@vger.kernel.org, leoyang.li@nxp.com,
	vladimir.oltean@nxp.com, will@kernel.org,
	catalin.marinas@arm.com,
	Kurt Kanzenbach <kurt.kanzenbach@linutronix.de>,
	Thomas Gleixner <tglx@linutronix.de>,
	mw@semihalf.com, Anna-Maria Gleixner <anna-maria@linutronix.de>,
	linux-arm-kernel@lists.infradead.org
Subject: Re: [RFC PATCH] arm64: defconfig: Disable fine-grained task level IRQ time accounting
Date: Mon, 03 Aug 2020 14:24:39 +0100	[thread overview]
Message-ID: <34b6cca5355f9e709554892261ac4b0c@kernel.org> (raw)
In-Reply-To: <jhjime0hrvw.mognet@arm.com>

On 2020-08-03 12:48, Valentin Schneider wrote:
> On 03/08/20 12:38, Vladimir Oltean wrote:
>> On Mon, Aug 03, 2020 at 10:51:32AM +0100, Robin Murphy wrote:
>>> 
>>> Having glanced across another thread that mentions IRQ accounting
>>> recently[1], I wonder if the underlying bug here might have something 
>>> do to
>>> with the stuff that Marc's trying to clean up.
>>> 
>>> Robin.
>>> 
>>> [1] 
>>> https://lore.kernel.org/linux-arm-kernel/20200624195811.435857-16-maz@kernel.org/
>> 
>> Thanks Robin. I've applied Marc's "[PATCH v2 00/17] arm/arm64: Turning
>> IPIs into normal interrupts" series and the LS1028A I'm debugging 
>> hangs
>> in absolutely the same way.
>> 
> 
> I'm not too surprised by that, wrt accounting this mostly changes where 
> the
> stores go to and barely shuffles when they happen (slightly earlier on 
> the
> IPI handling path).

Indeed. This series is just a "let's make things be the way they should 
be",
and isn't really fixing any bug. It actually may introduce a couple...

> FWIW I've had 'stress-ng --hrtimers 1' running on my Juno and eMAG for 
> ~15
> minutes and haven't had a splat yet.

I've started a couple of VMs with that workload too. 400K irq/s on an
8 vcpu guest, nothing to report so far.

But removing IRQ_TIME_ACCOUNTING from defconfig is a resounding "no 
way!".
It looks like we have a bug, and it should be squashed, not glanced 
over.

         M.
-- 
Jazz is not dead. It just smells funny...

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  reply	other threads:[~2020-08-03 13:26 UTC|newest]

Thread overview: 31+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2020-07-29  3:39 [RFC PATCH] arm64: defconfig: Disable fine-grained task level IRQ time accounting Alison Wang
2020-07-29  8:40 ` Kurt Kanzenbach
2020-07-29  8:50   ` [EXT] " Alison Wang
2020-07-29  9:49   ` Vladimir Oltean
2020-07-30  7:23     ` Kurt Kanzenbach
2020-07-30  8:22       ` Vladimir Oltean
2020-08-03  8:04         ` Kurt Kanzenbach
2020-08-03  8:16           ` Vladimir Oltean
2020-08-03  9:51             ` Robin Murphy
2020-08-03 11:38               ` Vladimir Oltean
2020-08-03 11:48                 ` Valentin Schneider
2020-08-03 13:24                   ` Marc Zyngier [this message]
2020-08-03 10:02             ` Thomas Gleixner
2020-08-03 10:49           ` Thomas Gleixner
2020-08-03 11:41             ` Vladimir Oltean
2020-08-03 15:13               ` Thomas Gleixner
2020-08-03 15:47                 ` Valentin Schneider
2020-08-03 16:14                   ` Vladimir Oltean
2020-08-03 19:22                   ` Thomas Gleixner
2020-08-03 23:59                     ` Valentin Schneider
2020-08-05  8:50                       ` Dietmar Eggemann
2020-08-05 13:40                     ` peterz
2020-08-05 13:56                       ` Valentin Schneider
2020-08-05 15:31                         ` peterz
2020-08-06  9:41                           ` Thomas Gleixner
2020-08-06 11:45                             ` peterz
2020-08-06 13:27                               ` Paul E. McKenney
2020-08-06 19:03                                 ` Thomas Gleixner
2020-08-06 20:39                                   ` Paul E. McKenney
2020-08-06 18:58                               ` Thomas Gleixner
2020-08-06  9:34                       ` Thomas Gleixner

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