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From: Steven Rostedt <rostedt@goodmis.org>
To: LKML <linux-kernel@vger.kernel.org>
Cc: "Ingo Molnar" <mingo@kernel.org>,
	"Peter Zijlstra" <peterz@infradead.org>,
	"Thomas Gleixner" <tglx@linutronix.de>,
	"Clark Williams" <williams@redhat.com>,
	linux-rt-users <linux-rt-users@vger.kernel.org>,
	"Mike Galbraith" <umgwanakikbuti@gmail.com>,
	"Paul E. McKenney" <paulmck@linux.vnet.ibm.com>,
	"Jörn Engel" <joern@purestorage.com>
Subject: Re: [RFC][PATCH v2] sched/rt: Use IPI to trigger RT task push migration instead of pulling
Date: Tue, 24 Feb 2015 16:23:39 -0500	[thread overview]
Message-ID: <20150224162339.36670d94@gandalf.local.home> (raw)
In-Reply-To: <20150224133946.3948c4b7@gandalf.local.home>

On Tue, 24 Feb 2015 13:39:46 -0500
Steven Rostedt <rostedt@goodmis.org> wrote:

> @@ -1775,6 +1946,15 @@ static int pull_rt_task(struct rq *this_
>  	 */
>  	smp_rmb();
>  
> +	/* Use local just in case a feature is switched in the middle of this */
> +	if ((use_ipi = sched_feat(RT_PUSH_IPI))) {
> +		/* Make sure the update to pending is visible here. */
> +		smp_rmb();

While porting this to the -rt kernel, I noticed that this rmb is
unneeded. It's already called above for a different reason :-p

-- Steve

> +
> +		/* If a push ipi is out, then we must do the old method */
> +		push_pending = READ_ONCE(this_rq->rt.push_csd_pending);
> +	}
> +
>  	for_each_cpu(cpu, this_rq->rd->rto_mask) {
>  		if (this_cpu == cpu)
>  			continue;

  parent reply	other threads:[~2015-02-24 21:23 UTC|newest]

Thread overview: 15+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2015-02-24 18:39 Steven Rostedt
2015-02-24 18:45 ` Steven Rostedt
2015-02-24 21:23 ` Steven Rostedt [this message]
2015-02-25 10:35 ` Peter Zijlstra
2015-02-25 15:51   ` Steven Rostedt
2015-02-25 17:11     ` Peter Zijlstra
2015-02-25 17:41       ` Peter Zijlstra
2015-02-25 17:50       ` Steven Rostedt
2015-02-26  7:45         ` Peter Zijlstra
2015-02-26 12:43           ` Steven Rostedt
2015-02-26 13:47             ` Peter Zijlstra
2015-02-26 14:00               ` Steven Rostedt
2015-02-26  7:49         ` Peter Zijlstra
2015-02-26 12:46           ` Steven Rostedt
2015-02-25  7:56 Hillf Danton

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