From: Sebastian Andrzej Siewior <bigeasy@linutronix.de>
To: Steven Rostedt <rostedt@goodmis.org>
Cc: Clark Williams <williams@redhat.com>,
LKML <linux-kernel@vger.kernel.org>,
Peter Zijlstra <peterz@infradead.org>,
Thomas Gleixner <tglx@linutronix.de>,
Ingo Molnar <mingo@kernel.org>,
Daniel Bristot de Oliveira <bristot@redhat.com>,
John Kacur <jkacur@redhat.com>, Scott Wood <swood@redhat.com>,
Mike Galbraith <efault@gmx.de>
Subject: Re: [PATCH RT] fix IPI balancing for 4.14-rt
Date: Thu, 23 Nov 2017 18:25:39 +0100 [thread overview]
Message-ID: <20171123172538.GB32454@linutronix.de> (raw)
In-Reply-To: <20171121102436.3e25655f@gandalf.local.home>
On 2017-11-21 10:24:36 [-0500], Steven Rostedt wrote:
> On Tue, 21 Nov 2017 09:14:25 -0600
> Clark Williams <williams@redhat.com> wrote:
>
> > I was testing 4.14-rt1 on a large system (cores == 96) and saw that
> > we were getting into an rt balancing storm, so I tried applying Steven's
> > patch (not upstream yet):
> >
> > sched/rt: Simplify the IPI rt balancing logic
> >
> Why is this patch necessary?
>
> Is it because you have the irq_work running in non hard irq context? I
> think you need something like this instead (if you haven't already
> added it):
I cherry-picked commit 4bdced5c9a29 ("sched/rt: Simplify the IPI based
RT balancing logic") and while refreshing the queue I noticed that the
irq_work struct moved and added the fix below into the original patch
where the IRQ_WORK_HARD_IRQ flag was added.
> -- Steve
>
> Index: linux-rt.git/kernel/sched/topology.c
> ===================================================================
> --- linux-rt.git.orig/kernel/sched/topology.c
> +++ linux-rt.git/kernel/sched/topology.c
> @@ -257,6 +257,7 @@ static int init_rootdomain(struct root_d
> rd->rto_cpu = -1;
> raw_spin_lock_init(&rd->rto_lock);
> init_irq_work(&rd->rto_push_work, rto_push_irq_work_func);
> + rd->rto_push_work.flags |= IRQ_WORK_HARD_IRQ;
> #endif
>
> init_dl_bw(&rd->dl_bw);
Sebastian
next prev parent reply other threads:[~2017-11-23 17:25 UTC|newest]
Thread overview: 7+ messages / expand[flat|nested] mbox.gz Atom feed top
2017-10-06 18:05 [PATCH tip/sched/core v3] sched/rt: Simplify the IPI rt balancing logic Steven Rostedt
2017-11-21 15:14 ` [PATCH RT] fix IPI balancing for 4.14-rt Clark Williams
2017-11-21 15:24 ` Steven Rostedt
2017-11-23 17:25 ` Sebastian Andrzej Siewior [this message]
2017-11-27 22:25 ` Steven Rostedt
2017-11-28 8:31 ` Sebastian Andrzej Siewior
2017-11-28 15:32 ` Steven Rostedt
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