From: Thomas Gleixner <tglx@linutronix.de>
To: peterz@infradead.org, Valentin Schneider <valentin.schneider@arm.com>
Cc: mw@semihalf.com, paulmck@kernel.org,
Anna-Maria Gleixner <anna-maria@linutronix.de>,
catalin.marinas@arm.com, Alison Wang <alison.wang@nxp.com>,
linux-kernel@vger.kernel.org, leoyang.li@nxp.com,
vladimir.oltean@nxp.com,
Kurt Kanzenbach <kurt.kanzenbach@linutronix.de>,
Vladimir Oltean <olteanv@gmail.com>,
will@kernel.org, linux-arm-kernel@lists.infradead.org
Subject: Re: [RFC PATCH] arm64: defconfig: Disable fine-grained task level IRQ time accounting
Date: Thu, 06 Aug 2020 11:41:06 +0200 [thread overview]
Message-ID: <874kpgi025.fsf@nanos.tec.linutronix.de> (raw)
In-Reply-To: <20200805153120.GU2674@hirez.programming.kicks-ass.net>
peterz@infradead.org writes:
> On Wed, Aug 05, 2020 at 02:56:49PM +0100, Valentin Schneider wrote:
>
>> I've been tempted to say the test case is a bit bogus, but am not familiar
>> enough with the RT throttling details to stand that ground. That said, from
>> both looking at the execution and the stress-ng source code, it seems to
>> unconditionally spawn 32 FIFO-50 tasks (there's even an option to make
>> these FIFO-99!!!), which is quite a crowd on monoCPU systems.
>
> Oh, so it's a case of: we do stupid without tuning and the system falls
> over. I can live with that.
It's not a question of whether you can live with that behaviour for a
particular silly test case.
The same happens with a single RT runaway task with enough interrupt
load on a UP machine. Just validated that. And that has nothing to do
with a silly test case. Sporadic runaways due to a bug in a once per
week code path simply can happen and having the safety net working
depending on a config option selected or not is just wrong.
Thanks,
tglx
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next prev parent reply other threads:[~2020-08-06 12:21 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
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 [this message]
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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