linux-kernel - Re: [PATCH 05/18] io-controller: Common hierarchical fair queuing code in elevaotor layer

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Message-ID: <20090508211749.GI7293@redhat.com>
Date:	Fri, 8 May 2009 17:17:49 -0400
From:	Vivek Goyal <vgoyal@...hat.com>
To:	Andrea Righi <righi.andrea@...il.com>
Cc:	nauman@...gle.com, dpshah@...gle.com, lizf@...fujitsu.com,
	mikew@...gle.com, fchecconi@...il.com, paolo.valente@...more.it,
	jens.axboe@...cle.com, ryov@...inux.co.jp, fernando@....ntt.co.jp,
	s-uchida@...jp.nec.com, taka@...inux.co.jp,
	guijianfeng@...fujitsu.com, jmoyer@...hat.com,
	dhaval@...ux.vnet.ibm.com, balbir@...ux.vnet.ibm.com,
	linux-kernel@...r.kernel.org,
	containers@...ts.linux-foundation.org, agk@...hat.com,
	dm-devel@...hat.com, snitzer@...hat.com, m-ikeda@...jp.nec.com,
	akpm@...ux-foundation.org
Subject: Re: [PATCH 05/18] io-controller: Common hierarchical fair queuing
	code in elevaotor layer

On Fri, May 08, 2009 at 11:09:37PM +0200, Andrea Righi wrote:
> On Tue, May 05, 2009 at 03:58:32PM -0400, Vivek Goyal wrote:
> > +#define STORE_FUNCTION(__VAR, __MIN, __MAX)				\
> > +static int io_cgroup_##__VAR##_write(struct cgroup *cgroup,		\
> > +					struct cftype *cftype,		\
> > +					u64 val)			\
> > +{									\
> > +	struct io_cgroup *iocg;					\
> > +	struct io_group *iog;						\
> > +	struct hlist_node *n;						\
> > +									\
> > +	if (val < (__MIN) || val > (__MAX))				\
> > +		return -EINVAL;						\
> > +									\
> > +	if (!cgroup_lock_live_group(cgroup))				\
> > +		return -ENODEV;						\
> > +									\
> > +	iocg = cgroup_to_io_cgroup(cgroup);				\
> > +									\
> > +	spin_lock_irq(&iocg->lock);					\
> > +	iocg->__VAR = (unsigned long)val;				\
> > +	hlist_for_each_entry(iog, n, &iocg->group_data, group_node) {	\
> > +		iog->entity.new_##__VAR = (unsigned long)val;		\
> > +		smp_wmb();						\
> > +		iog->entity.ioprio_changed = 1;				\
> > +	}								\
> > +	spin_unlock_irq(&iocg->lock);					\
> > +									\
> > +	cgroup_unlock();						\
> > +									\
> > +	return 0;							\
> > +}
> > +
> > +STORE_FUNCTION(weight, 0, WEIGHT_MAX);
> 
> A small fix: io.weight should be strictly greater than 0 if we don't
> want to automatically trigger the BUG_ON(entity->weight == 0) in
> bfq_calc_finish().
> 
> Signed-off-by: Andrea Righi <righi.andrea@...il.com>

Thanks Andrea. It worked previously as in previous version it was
io.ioprio and prio 0 was allowed and we calculated weights from priority.

Will include the fix in next version.

Thanks
Vivek

> ---
>  block/elevator-fq.c |    2 +-
>  1 files changed, 1 insertions(+), 1 deletions(-)
> 
> diff --git a/block/elevator-fq.c b/block/elevator-fq.c
> index 9500619..de25f44 100644
> --- a/block/elevator-fq.c
> +++ b/block/elevator-fq.c
> @@ -1136,7 +1136,7 @@ static int io_cgroup_##__VAR##_write(struct cgroup *cgroup,		\
>  	return 0;							\
>  }
>  
> -STORE_FUNCTION(weight, 0, WEIGHT_MAX);
> +STORE_FUNCTION(weight, 1, WEIGHT_MAX);
>  STORE_FUNCTION(ioprio_class, IOPRIO_CLASS_RT, IOPRIO_CLASS_IDLE);
>  #undef STORE_FUNCTION
>  
--
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