Date: Mon, 14 Oct 2013 13:33:01 +0200
From: Peter Zijlstra <peterz@infradead.org>
To: Juri Lelli <juri.lelli@gmail.com>
Cc: tglx@linutronix.de, mingo@redhat.com, rostedt@goodmis.org, oleg@redhat.com,
        fweisbec@gmail.com, darren@dvhart.com, johan.eker@ericsson.com,
        p.faure@akatech.ch, linux-kernel@vger.kernel.org,
        claudio@evidence.eu.com, michael@amarulasolutions.com,
        fchecconi@gmail.com, tommaso.cucinotta@sssup.it,
        nicola.manica@disi.unitn.it, luca.abeni@unitn.it,
        dhaval.giani@gmail.com, hgu1972@gmail.com, paulmck@linux.vnet.ibm.com,
        raistlin@linux.it, insop.song@gmail.com, liming.wang@windriver.com,
        jkacur@redhat.com, harald.gustafsson@ericsson.com,
        vincent.guittot@linaro.org,
        bruce.ashfield@windriver.com--no-chain-reply-to
Subject: Re: [PATCH 03/14] sched: SCHED_DEADLINE structures & implementation.
Message-ID: <20131014113301.GD3081@twins.programming.kicks-ass.net>
References: <1381747426-31334-1-git-send-email-juri.lelli@gmail.com>
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On Mon, Oct 14, 2013 at 12:43:35PM +0200, Juri Lelli wrote:
> +static void replenish_dl_entity(struct sched_dl_entity *dl_se)
> +{
> +	struct dl_rq *dl_rq = dl_rq_of_se(dl_se);
> +	struct rq *rq = rq_of_dl_rq(dl_rq);
> +
> +	/*
> +	 * We keep moving the deadline away until we get some
> +	 * available runtime for the entity. This ensures correct
> +	 * handling of situations where the runtime overrun is
> +	 * arbitrary large.
> +	 */
> +	while (dl_se->runtime <= 0) {
> +		dl_se->deadline += dl_se->dl_deadline;
> +		dl_se->runtime += dl_se->dl_runtime;
> +	}

Are we sure GCC won't be 'smart' and bite us; that is do we need
something like:

  asm("" : "+rm" (dl_se->runtime));

in there? See:

0d98bb2656e9 sched: Prevent compiler from optimising the sched_avg_update() loop

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