Re: [PATCH v2 2/3] sched/fair: Move hot load_avg into its own cacheline

Path	csiph.com!eternal-september.org!feeder.eternal-september.org!aioe.org!bofh.it!news.nic.it!robomod
From	Waiman Long <waiman.long@hpe.com>
Newsgroups	linux.kernel
Subject	Re: [PATCH v2 2/3] sched/fair: Move hot load_avg into its own cacheline
Date	Thu, 03 Dec 2015 20:40:02 +0100
Message-ID	<qBHTs-TI-5@gated-at.bofh.it> (permalink)
References	<qBkDv-2x9-3@gated-at.bofh.it> <qBkDw-2x9-23@gated-at.bofh.it> <qBzMe-3RU-3@gated-at.bofh.it>
X-Original-To	Peter Zijlstra <peterz@infradead.org>
User-Agent	Mozilla/5.0 (X11; Linux x86_64; rv:10.0.12) Gecko/20130109 Thunderbird/10.0.12
MIME-Version	1.0
Content-Type	text/plain; charset=ISO-8859-1; format=flowed
Content-Transfer-Encoding	7bit
Sender	robomod@news.nic.it
List-ID	<linux-kernel.vger.kernel.org>
X-Mailing-List	linux-kernel@vger.kernel.org
Approved	robomod@news.nic.it
Lines	41
Organization	linux.* mail to news gateway
X-Original-Cc	Ingo Molnar <mingo@redhat.com>, linux-kernel@vger.kernel.org, Yuyang Du <yuyang.du@intel.com>, Paul Turner <pjt@google.com>, Ben Segall <bsegall@google.com>, Morten Rasmussen <morten.rasmussen@arm.com>, Scott J Norton <scott.norton@hpe.com>, Douglas Hatch <doug.hatch@hpe.com>
X-Original-Date	Thu, 03 Dec 2015 14:38:16 -0500
X-Original-Message-ID	<56609A28.1090204@hpe.com>
X-Original-References	<1449081710-20185-1-git-send-email-Waiman.Long@hpe.com> <1449081710-20185-3-git-send-email-Waiman.Long@hpe.com> <20151203105607.GW3816@twins.programming.kicks-ass.net>
X-Original-Sender	linux-kernel-owner@vger.kernel.org
Xref	csiph.com linux.kernel:1283284

Show key headers only | View raw

On 12/03/2015 05:56 AM, Peter Zijlstra wrote:
> On Wed, Dec 02, 2015 at 01:41:49PM -0500, Waiman Long wrote:
>> +/*
>> + * Make sure that the task_group structure is cacheline aligned when
>> + * fair group scheduling is enabled.
>> + */
>> +#ifdef CONFIG_FAIR_GROUP_SCHED
>> +static inline struct task_group *alloc_task_group(void)
>> +{
>> +	return kmem_cache_alloc(task_group_cache, GFP_KERNEL | __GFP_ZERO);
>> +}
>> +
>> +static inline void free_task_group(struct task_group *tg)
>> +{
>> +	kmem_cache_free(task_group_cache, tg);
>> +}
>> +#else /* CONFIG_FAIR_GROUP_SCHED */
>> +static inline struct task_group *alloc_task_group(void)
>> +{
>> +	return kzalloc(sizeof(struct task_group), GFP_KERNEL);
>> +}
>> +
>> +static inline void free_task_group(struct task_group *tg)
>> +{
>> +	kfree(tg);
>> +}
>> +#endif /* CONFIG_FAIR_GROUP_SCHED */
> I think we can simply always use the kmem_cache, both slab and slub
> merge slabcaches where appropriate.

I did that as I was not sure how much overhead would the introduction of 
a new kmem_cache bring. It seems like it is not really an issue. So I am 
fine with making the kmem_cache change permanent.

Cheers,
Longman
--
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/

Thread

[PATCH v2 0/3] sched/fair: Reduce contention on tg's load_avg Waiman Long <Waiman.Long@hpe.com> - 2015-12-02 19:50 +0100
  [PATCH v2 1/3] sched/fair: Avoid redundant idle_cpu() call in update_sg_lb_stats() Waiman Long <Waiman.Long@hpe.com> - 2015-12-02 19:50 +0100
  [PATCH v2 3/3] sched/fair: Disable tg load_avg update for root_task_group Waiman Long <Waiman.Long@hpe.com> - 2015-12-02 19:50 +0100
    Re: [PATCH v2 3/3] sched/fair: Disable tg load_avg update for root_task_group bsegall@google.com - 2015-12-02 21:00 +0100
    [tip:sched/core] sched/fair:   Disable the task group load_avg update for the root_task_group tip-bot for Waiman Long <tipbot@zytor.com> - 2015-12-04 13:00 +0100
  [PATCH v2 2/3] sched/fair: Move hot load_avg into its own cacheline Waiman Long <Waiman.Long@hpe.com> - 2015-12-02 19:50 +0100
    Re: [PATCH v2 2/3] sched/fair: Move hot load_avg into its own cacheline bsegall@google.com - 2015-12-02 21:10 +0100
      Re: [PATCH v2 2/3] sched/fair: Move hot load_avg into its own cacheline Waiman Long <waiman.long@hpe.com> - 2015-12-03 20:30 +0100
        Re: [PATCH v2 2/3] sched/fair: Move hot load_avg into its own cacheline bsegall@google.com - 2015-12-03 20:50 +0100
    Re: [PATCH v2 2/3] sched/fair: Move hot load_avg into its own  cacheline Mike Galbraith <umgwanakikbuti@gmail.com> - 2015-12-03 05:40 +0100
      Re: [PATCH v2 2/3] sched/fair: Move hot load_avg into its own cacheline Waiman Long <waiman.long@hpe.com> - 2015-12-03 20:40 +0100
        Re: [PATCH v2 2/3] sched/fair: Move hot load_avg into its own  cacheline Mike Galbraith <umgwanakikbuti@gmail.com> - 2015-12-04 03:10 +0100
          Re: [PATCH v2 2/3] sched/fair: Move hot load_avg into its own cacheline Waiman Long <waiman.long@hpe.com> - 2015-12-04 21:20 +0100
    Re: [PATCH v2 2/3] sched/fair: Move hot load_avg into its own  cacheline Peter Zijlstra <peterz@infradead.org> - 2015-12-03 12:00 +0100
      Re: [PATCH v2 2/3] sched/fair: Move hot load_avg into its own cacheline Waiman Long <waiman.long@hpe.com> - 2015-12-03 20:40 +0100
    Re: [PATCH v2 2/3] sched/fair: Move hot load_avg into its own  cacheline Peter Zijlstra <peterz@infradead.org> - 2015-12-03 12:20 +0100
      Re: [PATCH v2 2/3] sched/fair: Move hot load_avg into its own cacheline bsegall@google.com - 2015-12-03 19:10 +0100
        Re: [PATCH v2 2/3] sched/fair: Move hot load_avg into its own  cacheline Peter Zijlstra <peterz@infradead.org> - 2015-12-03 19:20 +0100
          Re: [PATCH v2 2/3] sched/fair: Move hot load_avg into its own cacheline bsegall@google.com - 2015-12-03 19:30 +0100
      Re: [PATCH v2 2/3] sched/fair: Move hot load_avg into its own cacheline Waiman Long <waiman.long@hpe.com> - 2015-12-03 21:00 +0100
        Re: [PATCH v2 2/3] sched/fair: Move hot load_avg into its own  cacheline Peter Zijlstra <peterz@infradead.org> - 2015-12-03 21:10 +0100
    [tip:sched/core] sched/fair: Move the cache-hot 'load_avg'   variable into its own cacheline tip-bot for Waiman Long <tipbot@zytor.com> - 2015-12-04 13:00 +0100

csiph-web