linux-kernel - Re: [RFC v5 PATCH 1/8] sched: Rename struct rt_bandwidth to sched

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Date:	Fri, 29 Jan 2010 14:29:49 +0530
From:	Balbir Singh <balbir@...ux.vnet.ibm.com>
To:	Bharata B Rao <bharata@...ux.vnet.ibm.com>
Cc:	linux-kernel@...r.kernel.org,
	Dhaval Giani <dhaval@...ux.vnet.ibm.com>,
	Vaidyanathan Srinivasan <svaidy@...ux.vnet.ibm.com>,
	Gautham R Shenoy <ego@...ibm.com>,
	Srivatsa Vaddagiri <vatsa@...ibm.com>,
	Kamalesh Babulal <kamalesh@...ux.vnet.ibm.com>,
	Ingo Molnar <mingo@...e.hu>,
	Peter Zijlstra <a.p.zijlstra@...llo.nl>,
	Pavel Emelyanov <xemul@...nvz.org>,
	Herbert Poetzl <herbert@...hfloor.at>,
	Avi Kivity <avi@...hat.com>,
	Chris Friesen <cfriesen@...tel.com>,
	Paul Menage <menage@...gle.com>,
	Mike Waychison <mikew@...gle.com>
Subject: Re: [RFC v5 PATCH 1/8] sched: Rename struct rt_bandwidth to
 sched_bandwidth

* Bharata B Rao <bharata@...ux.vnet.ibm.com> [2010-01-05 13:28:24]:

> sched: Rename struct rt_bandwidth to sched_bandwidth
> 
> From: Dhaval Giani <dhaval@...ux.vnet.ibm.com>
> 
> Rename struct rt_bandwidth to sched_bandwidth and rename some of the
> routines to generic names (s/rt_/sched_) so that they can be used
> by CFS hard limits code in the subsequent patches.
> 
> No functionality change by this patch.
> 
> Signed-off-by: Dhaval Giani <dhaval@...ux.vnet.ibm.com>
> Signed-off-by: Bharata B Rao <bharata@...ux.vnet.ibm.com>

Looks good, some nit picks below

Acked-by: Balbir Singh <balbir@...ux.vnet.ibm.com>
 

> ---
>  kernel/sched.c    |  127 ++++++++++++++++++++++++++---------------------------
>  kernel/sched_rt.c |   46 ++++++++++---------
>  2 files changed, 86 insertions(+), 87 deletions(-)
> 
> diff --git a/kernel/sched.c b/kernel/sched.c
> index c535cc4..21cf0d5 100644
> --- a/kernel/sched.c
> +++ b/kernel/sched.c
> @@ -139,50 +139,50 @@ struct rt_prio_array {
>  	struct list_head queue[MAX_RT_PRIO];
>  };
> 
> -struct rt_bandwidth {
> +struct sched_bandwidth {
>  	/* nests inside the rq lock: */
> -	raw_spinlock_t		rt_runtime_lock;
> -	ktime_t			rt_period;
> -	u64			rt_runtime;
> -	struct hrtimer		rt_period_timer;
> +	raw_spinlock_t		runtime_lock;
> +	ktime_t			period;
> +	u64			runtime;
> +	struct hrtimer		period_timer;
>  };
> 
> -static struct rt_bandwidth def_rt_bandwidth;
> +static struct sched_bandwidth def_rt_bandwidth;
> 
> -static int do_sched_rt_period_timer(struct rt_bandwidth *rt_b, int overrun);
> +static int do_sched_rt_period_timer(struct sched_bandwidth *sched_b, int overrun);
> 
>  static enum hrtimer_restart sched_rt_period_timer(struct hrtimer *timer)
>  {
> -	struct rt_bandwidth *rt_b =
> -		container_of(timer, struct rt_bandwidth, rt_period_timer);
> +	struct sched_bandwidth *sched_b =
> +		container_of(timer, struct sched_bandwidth, period_timer);
>  	ktime_t now;
>  	int overrun;
>  	int idle = 0;
> 
>  	for (;;) {
>  		now = hrtimer_cb_get_time(timer);
> -		overrun = hrtimer_forward(timer, now, rt_b->rt_period);
> +		overrun = hrtimer_forward(timer, now, sched_b->period);
> 
>  		if (!overrun)
>  			break;
> 
> -		idle = do_sched_rt_period_timer(rt_b, overrun);
> +		idle = do_sched_rt_period_timer(sched_b, overrun);
>  	}
> 
>  	return idle ? HRTIMER_NORESTART : HRTIMER_RESTART;
>  }
> 
> -static
> -void init_rt_bandwidth(struct rt_bandwidth *rt_b, u64 period, u64 runtime)
> +static void init_sched_bandwidth(struct sched_bandwidth *sched_b, u64 period,
> +	u64 runtime, enum hrtimer_restart (*period_timer)(struct hrtimer *))
>  {
> -	rt_b->rt_period = ns_to_ktime(period);
> -	rt_b->rt_runtime = runtime;
> +	sched_b->period = ns_to_ktime(period);
> +	sched_b->runtime = runtime;
> 
> -	raw_spin_lock_init(&rt_b->rt_runtime_lock);
> +	raw_spin_lock_init(&sched_b->runtime_lock);
> 
> -	hrtimer_init(&rt_b->rt_period_timer,
> +	hrtimer_init(&sched_b->period_timer,
>  			CLOCK_MONOTONIC, HRTIMER_MODE_REL);
> -	rt_b->rt_period_timer.function = sched_rt_period_timer;
> +	sched_b->period_timer.function = *period_timer;

Hmm.. may be I forgetting the "C" language, but why do you dereference
the pointer before assignment? You should be able to directly assign a
function address to the function pointer. Did you see a warning?

>  }
> 
>  static inline int rt_bandwidth_enabled(void)
> @@ -190,42 +190,40 @@ static inline int rt_bandwidth_enabled(void)
>  	return sysctl_sched_rt_runtime >= 0;
>  }
> 
> -static void start_rt_bandwidth(struct rt_bandwidth *rt_b)
> +static void start_sched_bandwidth(struct sched_bandwidth *sched_b)
>  {
>  	ktime_t now;
> 
> -	if (!rt_bandwidth_enabled() || rt_b->rt_runtime == RUNTIME_INF)
> +	if (!rt_bandwidth_enabled() || sched_b->runtime == RUNTIME_INF)
>  		return;
> 
> -	if (hrtimer_active(&rt_b->rt_period_timer))
> +	if (hrtimer_active(&sched_b->period_timer))
>  		return;
> 
> -	raw_spin_lock(&rt_b->rt_runtime_lock);
> +	raw_spin_lock(&sched_b->runtime_lock);

I don't quite understand why this is a raw_spin_lock

[snip]

-- 
	Balbir
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