linux-kernel - Re: [patch 03/15] sched: introduce primitives to account for CFS bandwidth tracking

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Date:	Tue, 10 May 2011 16:18:38 +0900
From:	Hidetoshi Seto <seto.hidetoshi@...fujitsu.com>
To:	Paul Turner <pjt@...gle.com>
CC:	linux-kernel@...r.kernel.org,
	Peter Zijlstra <a.p.zijlstra@...llo.nl>,
	Bharata B Rao <bharata@...ux.vnet.ibm.com>,
	Dhaval Giani <dhaval.giani@...il.com>,
	Balbir Singh <balbir@...ux.vnet.ibm.com>,
	Vaidyanathan Srinivasan <svaidy@...ux.vnet.ibm.com>,
	Srivatsa Vaddagiri <vatsa@...ibm.com>,
	Kamalesh Babulal <kamalesh@...ux.vnet.ibm.com>,
	Ingo Molnar <mingo@...e.hu>,
	Pavel Emelyanov <xemul@...nvz.org>,
	Nikhil Rao <ncrao@...gle.com>
Subject: Re: [patch 03/15] sched: introduce primitives to account for CFS
 bandwidth tracking

One nitpicking...

(2011/05/03 18:28), Paul Turner wrote:
> In this patch we introduce the notion of CFS bandwidth, partitioned into 
> globally unassigned bandwidth, and locally claimed bandwidth.
> 
> - The global bandwidth is per task_group, it represents a pool of unclaimed
>   bandwidth that cfs_rqs can allocate from.  
> - The local bandwidth is tracked per-cfs_rq, this represents allotments from
>   the global pool bandwidth assigned to a specific cpu.
> 
> Bandwidth is managed via cgroupfs, adding two new interfaces to the cpu subsystem:
> - cpu.cfs_period_us : the bandwidth period in usecs
> - cpu.cfs_quota_us : the cpu bandwidth (in usecs) that this tg will be allowed
>   to consume over period above.
> 
> Signed-off-by: Paul Turner <pjt@...gle.com>
> Signed-off-by: Nikhil Rao <ncrao@...gle.com>
> Signed-off-by: Bharata B Rao <bharata@...ux.vnet.ibm.com>
> ---

(snip)

> @@ -369,9 +379,45 @@ struct cfs_rq {
>  
>  	unsigned long load_contribution;
>  #endif
> +#ifdef CONFIG_CFS_BANDWIDTH
> +	int runtime_enabled;
> +	s64 runtime_remaining;
> +#endif
>  #endif
>  };
>  
> +#ifdef CONFIG_CFS_BANDWIDTH
> +static inline struct cfs_bandwidth *tg_cfs_bandwidth(struct task_group *tg)
> +{
> +	return &tg->cfs_bandwidth;
> +}
> +
> +static inline u64 default_cfs_period(void);
> +
> +static void init_cfs_bandwidth(struct cfs_bandwidth *cfs_b)
> +{
> +	raw_spin_lock_init(&cfs_b->lock);
> +	cfs_b->quota = RUNTIME_INF;
> +	cfs_b->period = ns_to_ktime(default_cfs_period());
> +}
> +
> +static void init_cfs_rq_runtime(struct cfs_rq *cfs_rq)
> +{
> +	cfs_rq->runtime_remaining = 0;
> +	cfs_rq->runtime_enabled = 0;
> +}
> +
> +static void destroy_cfs_bandwidth(struct cfs_bandwidth *cfs_b)
> +{}
> +#else
> +#ifdef CONFIG_FAIR_GROUP_SCHED
> +static void init_cfs_rq_runtime(struct cfs_rq *cfs_rq) {}
> +void init_cfs_bandwidth(struct cfs_bandwidth *cfs_b) {}

Nit: why not static?

> +static void destroy_cfs_bandwidth(struct cfs_bandwidth *cfs_b) {}
> +#endif /* CONFIG_FAIR_GROUP_SCHED */
> +static void start_cfs_bandwidth(struct cfs_rq *cfs_rq) {}
> +#endif /* CONFIG_CFS_BANDWIDTH */
> +
>  /* Real-Time classes' related field in a runqueue: */
>  struct rt_rq {
>  	struct rt_prio_array active;

The rest looks good for me.

Reviewed-by: Hidetoshi Seto <seto.hidetoshi@...fujitsu.com>


Thanks,
H.Seto

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