Subject: Re: [PATCH 07/10] sched: Migrate sched to use new tick dependency
 mask model
To: Frederic Weisbecker <fweisbec@gmail.com>,
        LKML <linux-kernel@vger.kernel.org>
References: <1437669735-8786-1-git-send-email-fweisbec@gmail.com>
 <1437669735-8786-8-git-send-email-fweisbec@gmail.com>
CC: Peter Zijlstra <peterz@infradead.org>,
        Thomas Gleixner <tglx@linutronix.de>,
        Preeti U Murthy <preeti@linux.vnet.ibm.com>,
        Christoph Lameter <cl@linux.com>, Ingo Molnar <mingo@kernel.org>,
        Viresh Kumar <viresh.kumar@linaro.org>, Rik van Riel <riel@redhat.com>
From: Chris Metcalf <cmetcalf@ezchip.com>
Message-ID: <55B26E4A.80209@ezchip.com>
Date: Fri, 24 Jul 2015 12:56:42 -0400
User-Agent: Mozilla/5.0 (X11; Linux i686 on x86_64; rv:38.0) Gecko/20100101
 Thunderbird/38.1.0
MIME-Version: 1.0
In-Reply-To: <1437669735-8786-8-git-send-email-fweisbec@gmail.com>
Content-Type: text/plain; charset="windows-1252"; format=flowed
Content-Transfer-Encoding: 7bit
DB5PR02MB0776: X-MS-Exchange-Organization-RulesExecuted
SpamDiagnosticOutput: 1:23
SpamDiagnosticMetadata: NSPM
X-MS-Exchange-CrossTenant-OriginalArrivalTime: 24 Jul 2015 16:56:51.4477 (UTC)
X-MS-Exchange-CrossTenant-FromEntityHeader: Hosted
X-MS-Exchange-Transport-CrossTenantHeadersStamped: DB5PR02MB0776
Sender: linux-kernel-owner@vger.kernel.org
List-ID: <linux-kernel.vger.kernel.org>
X-Mailing-List: linux-kernel@vger.kernel.org
Content-Length: 892
Lines: 29

On 07/23/2015 12:42 PM, Frederic Weisbecker wrote:
> +static inline void sched_update_tick_dependency(struct rq *rq)
> +{
> +	int cpu;
> +
> +	if (!tick_nohz_full_enabled())
> +		return;
> +
> +	cpu = cpu_of(rq);
> +
> +	if (!tick_nohz_full_cpu(rq->cpu))
> +		return;
> +
> +	if (sched_can_stop_tick(rq))
> +		tick_nohz_clear_tick_dependency_cpu(TICK_SCHED_BIT, cpu);
> +	else
> +		tick_nohz_set_tick_dependency_cpu(TICK_SCHED_BIT, cpu);
> +}

Is it worth asserting that the rq is locked at this point? Presumably 
that's a requirement so that the cpu can't change out from under you.
-- 
Chris Metcalf, EZChip Semiconductor
http://www.ezchip.com
--
To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
the body of a message to majordomo@vger.kernel.org
More majordomo info at  http://vger.kernel.org/majordomo-info.html
Please read the FAQ at  http://www.tux.org/lkml/