linux-kernel - Re: [PATCH 02/10] Common flat fair queuing code in elevaotor layer

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Date:	Thu, 19 Mar 2009 14:27:14 +0800
From:	Gui Jianfeng <guijianfeng@...fujitsu.com>
To:	Vivek Goyal <vgoyal@...hat.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@...ellilink.co.jp, s-uchida@...jp.nec.com,
	taka@...inux.co.jp, arozansk@...hat.com, jmoyer@...hat.com,
	oz-kernel@...hat.com, dhaval@...ux.vnet.ibm.com,
	balbir@...ux.vnet.ibm.com, linux-kernel@...r.kernel.org,
	containers@...ts.linux-foundation.org, akpm@...ux-foundation.org,
	menage@...gle.com, peterz@...radead.org
Subject: Re: [PATCH 02/10] Common flat fair queuing code in elevaotor layer

Vivek Goyal wrote:
...
> +
> +int elv_init_ioq(struct elevator_queue *eq, struct io_queue *ioq,
> +			void *sched_queue, int ioprio_class, int ioprio,
> +			int is_sync)
> +{
> +	struct elv_fq_data *efqd = &eq->efqd;
> +	struct io_group *iog = io_lookup_io_group_current(efqd->queue);
> +
> +	RB_CLEAR_NODE(&ioq->entity.rb_node);
> +	atomic_set(&ioq->ref, 0);
> +	ioq->efqd = efqd;
> +	ioq->entity.budget = efqd->elv_slice[is_sync];
> +	elv_ioq_set_ioprio_class(ioq, ioprio_class);
> +	elv_ioq_set_ioprio(ioq, ioprio);
> +	ioq->pid = current->pid;

  Hi Vivek,

  If we are using a scheduler other than cfq, IOW single ioq is used.
  that storing a pid to the ioq makes no sense, it just stores the first 
  serviced task.

> +	ioq->sched_queue = sched_queue;
> +	elv_mark_ioq_idle_window(ioq);
> +	bfq_init_entity(&ioq->entity, iog);
> +	return 0;
> +}
> +EXPORT_SYMBOL(elv_init_ioq);
...
> +
> +extern int elv_slice_idle;
> +extern int elv_slice_async;
> +
> +/* Logging facilities. */
> +#define elv_log_ioq(efqd, ioq, fmt, args...) \
> +	blk_add_trace_msg((efqd)->queue, "%d" fmt, (ioq)->pid, ##args)

   Maybe we need to use current->pid instead, for ioq->pid is not valid
   sometimes.

> +
> +#define elv_log(efqd, fmt, args...) \
> +	blk_add_trace_msg((efqd)->queue, "" fmt, ##args)
> +
> +#define ioq_sample_valid(samples)   ((samples) > 80)
> +


-- 
Regards
Gui Jianfeng

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