From: Sebastian Andrzej Siewior <bigeasy@linutronix.de>
To: Henri Roosen <henri.roosen@ginzinger.com>
Cc: "linux-rt-users@vger.kernel.org" <linux-rt-users@vger.kernel.org>
Subject: Re: INFO: rcu_preempt detected stalls on CPUs/tasks
Date: Fri, 29 Jul 2016 18:46:58 +0200 [thread overview]
Message-ID: <20160729164658.GH21715@linutronix.de> (raw)
In-Reply-To: <150d1d1f-b427-50be-524d-dbe80dd5523e@ginzinger.com>
* Henri Roosen | 2016-07-15 12:54:25 [+0200]:
>The problem is easily triggered, but only after starting a flood-ping to
>the PREEMPT_RT-system under test. This also results in huge latency,
>much bigger than on a 'normal' PREEMPT-system, which seems to be
>resistant against the flood-ping.
>
>Any suggestions how to best trace this down?
Hmm. 4.1.27-rt30 has
softirq: split timer softirqs out of ksoftirqd
net: provide a way to delegate processing a softirq to ksoftirqd
I would suggest using those two but you should have them.
Your ksoftirqd runs as SCHED_OTHER, right? And you do have
CONFIG_RCU_BOOST enabled? Your do_hell script which starts hackbench
does not run with higher priority?
>From the backtrace it is hackbench "doing things" and this one should be
preempted by RCU and ethernet networking napi code should be preempted /
moved to ksoftirqd during the flood-ping. Can you check this happens?
>Thanks,
>Henri
Sebastian
next prev parent reply other threads:[~2016-07-29 16:47 UTC|newest]
Thread overview: 5+ messages / expand[flat|nested] mbox.gz Atom feed top
2016-06-30 16:05 INFO: rcu_preempt detected stalls on CPUs/tasks Roosen Henri
2016-07-14 15:27 ` Sebastian Andrzej Siewior
2016-07-15 10:54 ` Henri Roosen
2016-07-29 16:46 ` Sebastian Andrzej Siewior [this message]
2016-10-19 15:17 ` Henri Roosen
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