Message-ID: <20090514151558.GA31234@redhat.com>
Date:	Thu, 14 May 2009 11:15:58 -0400
From:	Vivek Goyal <vgoyal@...hat.com>
To:	Gui Jianfeng <guijianfeng@...fujitsu.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, jmoyer@...hat.com,
	dhaval@...ux.vnet.ibm.com, balbir@...ux.vnet.ibm.com,
	linux-kernel@...r.kernel.org,
	containers@...ts.linux-foundation.org, righi.andrea@...il.com,
	agk@...hat.com, dm-devel@...hat.com, snitzer@...hat.com,
	m-ikeda@...jp.nec.com, akpm@...ux-foundation.org
Subject: Re: [PATCH] IO Controller: Add per-device weight and ioprio_class
	handling

On Thu, May 14, 2009 at 03:26:35PM +0800, Gui Jianfeng wrote:
> Hi Vivek,
> 
> This patch enables per-cgroup per-device weight and ioprio_class handling.
> A new cgroup interface "policy" is introduced. You can make use of this 
> file to configure weight and ioprio_class for each device in a given cgroup.
> The original "weight" and "ioprio_class" files are still available. If you
> don't do special configuration for a particular device, "weight" and 
> "ioprio_class" are used as default values in this device.
> 
> You can use the following format to play with the new interface.
> #echo DEV:weight:ioprio_class > /patch/to/cgroup/policy
> weight=0 means removing the policy for DEV.
> 
> Examples:
> Configure weight=300 ioprio_class=2 on /dev/hdb in this cgroup
> # echo /dev/hdb:300:2 > io.policy
> # cat io.policy
> dev weight class
> /dev/hdb 300 2
> 
> Configure weight=500 ioprio_class=1 on /dev/hda in this cgroup
> # echo /dev/hda:500:1 > io.policy
> # cat io.policy
> dev weight class
> /dev/hda 500 1
> /dev/hdb 300 2
> 
> Remove the policy for /dev/hda in this cgroup
> # echo /dev/hda:0:1 > io.policy
> # cat io.policy
> dev weight class
> /dev/hdb 300 2
> 
> Changelog (v1 -> v2)
> - Rename some structures
> - Use spin_lock_irqsave() and spin_lock_irqrestore() version to prevent
>   from enabling the interrupts unconditionally.
> - Fix policy setup bug when switching to another io scheduler.
> - If a policy is available for a specific device, don't update weight and
>   io class when writing "weight" and "iprio_class".
> - Fix a bug when parsing policy string.
> 
> Signed-off-by: Gui Jianfeng <guijianfeng@...fujitsu.com>
> ---

Thanks a lot Gui. This patch seems to be working fine for me now. I will
continue to do more testing and let you know if there are more issues. I 
will include it in next posting (V3).

Thanks
Vivek

>  block/elevator-fq.c |  258 +++++++++++++++++++++++++++++++++++++++++++++++++--
>  block/elevator-fq.h |   12 +++
>  2 files changed, 261 insertions(+), 9 deletions(-)
> 
> diff --git a/block/elevator-fq.c b/block/elevator-fq.c
> index 69435ab..43b30a4 100644
> --- a/block/elevator-fq.c
> +++ b/block/elevator-fq.c
> @@ -12,6 +12,9 @@
>  #include "elevator-fq.h"
>  #include <linux/blktrace_api.h>
>  #include <linux/biotrack.h>
> +#include <linux/seq_file.h>
> +#include <linux/genhd.h>
> +
>  
>  /* Values taken from cfq */
>  const int elv_slice_sync = HZ / 10;
> @@ -1045,12 +1048,31 @@ struct io_group *io_lookup_io_group_current(struct request_queue *q)
>  }
>  EXPORT_SYMBOL(io_lookup_io_group_current);
>  
> -void io_group_init_entity(struct io_cgroup *iocg, struct io_group *iog)
> +static struct io_policy_node *policy_search_node(const struct io_cgroup *iocg,
> +						 dev_t dev);
> +
> +void io_group_init_entity(struct io_cgroup *iocg, struct io_group *iog,
> +			  dev_t dev)
>  {
>  	struct io_entity *entity = &iog->entity;
> +	struct io_policy_node *pn;
> +	unsigned long flags;
> +
> +	spin_lock_irqsave(&iocg->lock, flags);
> +	pn = policy_search_node(iocg, dev);
> +	if (pn) {
> +		entity->weight = pn->weight;
> +		entity->new_weight = pn->weight;
> +		entity->ioprio_class = pn->ioprio_class;
> +		entity->new_ioprio_class = pn->ioprio_class;
> +	} else {
> +		entity->weight = iocg->weight;
> +		entity->new_weight = iocg->weight;
> +		entity->ioprio_class = iocg->ioprio_class;
> +		entity->new_ioprio_class = iocg->ioprio_class;
> +	}
> +	spin_unlock_irqrestore(&iocg->lock, flags);
>  
> -	entity->weight = entity->new_weight = iocg->weight;
> -	entity->ioprio_class = entity->new_ioprio_class = iocg->ioprio_class;
>  	entity->ioprio_changed = 1;
>  	entity->my_sched_data = &iog->sched_data;
>  }
> @@ -1114,6 +1136,7 @@ static int io_cgroup_##__VAR##_write(struct cgroup *cgroup,		\
>  	struct io_cgroup *iocg;					\
>  	struct io_group *iog;						\
>  	struct hlist_node *n;						\
> +	struct io_policy_node *pn;					\
>  									\
>  	if (val < (__MIN) || val > (__MAX))				\
>  		return -EINVAL;						\
> @@ -1126,6 +1149,9 @@ static int io_cgroup_##__VAR##_write(struct cgroup *cgroup,		\
>  	spin_lock_irq(&iocg->lock);					\
>  	iocg->__VAR = (unsigned long)val;				\
>  	hlist_for_each_entry(iog, n, &iocg->group_data, group_node) {	\
> +		pn = policy_search_node(iocg, iog->dev);		\
> +		if (pn)							\
> +			continue;					\
>  		iog->entity.new_##__VAR = (unsigned long)val;		\
>  		smp_wmb();						\
>  		iog->entity.ioprio_changed = 1;				\
> @@ -1237,7 +1263,7 @@ static u64 io_cgroup_disk_sectors_read(struct cgroup *cgroup,
>   * to the root has already an allocated group on @bfqd.
>   */
>  struct io_group *io_group_chain_alloc(struct request_queue *q, void *key,
> -					struct cgroup *cgroup)
> +				      struct cgroup *cgroup, struct bio *bio)
>  {
>  	struct io_cgroup *iocg;
>  	struct io_group *iog, *leaf = NULL, *prev = NULL;
> @@ -1263,12 +1289,17 @@ struct io_group *io_group_chain_alloc(struct request_queue *q, void *key,
>  		atomic_set(&iog->ref, 0);
>  		iog->deleting = 0;
>  
> -		io_group_init_entity(iocg, iog);
> -		iog->my_entity = &iog->entity;
>  #ifdef CONFIG_DEBUG_GROUP_IOSCHED
>  		iog->iocg_id = css_id(&iocg->css);
> +		if (bio) {
> +			struct gendisk *disk = bio->bi_bdev->bd_disk;
> +			iog->dev = MKDEV(disk->major, disk->first_minor);
> +		}
>  #endif
>  
> +		io_group_init_entity(iocg, iog, iog->dev);
> +		iog->my_entity = &iog->entity;
> +
>  		blk_init_request_list(&iog->rl);
>  
>  		if (leaf == NULL) {
> @@ -1379,7 +1410,7 @@ void io_group_chain_link(struct request_queue *q, void *key,
>   */
>  struct io_group *io_find_alloc_group(struct request_queue *q,
>  			struct cgroup *cgroup, struct elv_fq_data *efqd,
> -			int create)
> +			     int create, struct bio *bio)
>  {
>  	struct io_cgroup *iocg = cgroup_to_io_cgroup(cgroup);
>  	struct io_group *iog = NULL;
> @@ -1390,7 +1421,7 @@ struct io_group *io_find_alloc_group(struct request_queue *q,
>  	if (iog != NULL || !create)
>  		return iog;
>  
> -	iog = io_group_chain_alloc(q, key, cgroup);
> +	iog = io_group_chain_alloc(q, key, cgroup, bio);
>  	if (iog != NULL)
>  		io_group_chain_link(q, key, cgroup, iog, efqd);
>  
> @@ -1489,7 +1520,7 @@ struct io_group *io_get_io_group_bio(struct request_queue *q, struct bio *bio,
>  		goto out;
>  	}
>  
> -	iog = io_find_alloc_group(q, cgroup, efqd, create);
> +	iog = io_find_alloc_group(q, cgroup, efqd, create, bio);
>  	if (!iog) {
>  		if (create)
>  			iog = efqd->root_group;
> @@ -1549,8 +1580,209 @@ struct io_group *io_alloc_root_group(struct request_queue *q,
>  	return iog;
>  }
>  
> +static int io_cgroup_policy_read(struct cgroup *cgrp, struct cftype *cft,
> +				  struct seq_file *m)
> +{
> +	struct io_cgroup *iocg;
> +	struct io_policy_node *pn;
> +
> +	iocg = cgroup_to_io_cgroup(cgrp);
> +
> +	if (list_empty(&iocg->policy_list))
> +		goto out;
> +
> +	seq_printf(m, "dev weight class\n");
> +
> +	spin_lock_irq(&iocg->lock);
> +	list_for_each_entry(pn, &iocg->policy_list, node) {
> +		seq_printf(m, "%s %lu %lu\n", pn->dev_name,
> +			   pn->weight, pn->ioprio_class);
> +	}
> +	spin_unlock_irq(&iocg->lock);
> +out:
> +	return 0;
> +}
> +
> +static inline void policy_insert_node(struct io_cgroup *iocg,
> +					  struct io_policy_node *pn)
> +{
> +	list_add(&pn->node, &iocg->policy_list);
> +}
> +
> +/* Must be called with iocg->lock held */
> +static inline void policy_delete_node(struct io_policy_node *pn)
> +{
> +	list_del(&pn->node);
> +}
> +
> +/* Must be called with iocg->lock held */
> +static struct io_policy_node *policy_search_node(const struct io_cgroup *iocg,
> +						 dev_t dev)
> +{
> +	struct io_policy_node *pn;
> +
> +	if (list_empty(&iocg->policy_list))
> +		return NULL;
> +
> +	list_for_each_entry(pn, &iocg->policy_list, node) {
> +		if (pn->dev == dev)
> +			return pn;
> +	}
> +
> +	return NULL;
> +}
> +
> +static int devname_to_devnum(const char *buf, dev_t *dev)
> +{
> +	struct block_device *bdev;
> +	struct gendisk *disk;
> +	int part;
> +
> +	bdev = lookup_bdev(buf);
> +	if (IS_ERR(bdev))
> +		return -ENODEV;
> +
> +	disk = get_gendisk(bdev->bd_dev, &part);
> +	*dev = MKDEV(disk->major, disk->first_minor);
> +	bdput(bdev);
> +
> +	return 0;
> +}
> +
> +static int policy_parse_and_set(char *buf, struct io_policy_node *newpn)
> +{
> +	char *s[3], *p;
> +	int ret;
> +	int i = 0;
> +
> +	memset(s, 0, sizeof(s));
> +	while ((p = strsep(&buf, ":")) != NULL) {
> +		if (!*p)
> +			continue;
> +		s[i++] = p;
> +	}
> +
> +	ret = devname_to_devnum(s[0], &newpn->dev);
> +	if (ret)
> +		return ret;
> +
> +	strcpy(newpn->dev_name, s[0]);
> +
> +	if (s[1] == NULL)
> +		return -EINVAL;
> +
> +	ret = strict_strtoul(s[1], 10, &newpn->weight);
> +	if (ret || newpn->weight > WEIGHT_MAX)
> +		return -EINVAL;
> +
> +	if (s[2] == NULL)
> +		return -EINVAL;
> +
> +	ret = strict_strtoul(s[2], 10, &newpn->ioprio_class);
> +	if (ret || newpn->ioprio_class < IOPRIO_CLASS_RT ||
> +	    newpn->ioprio_class > IOPRIO_CLASS_IDLE)
> +		return -EINVAL;
> +
> +	return 0;
> +}
> +
> +static int io_cgroup_policy_write(struct cgroup *cgrp, struct cftype *cft,
> +			    const char *buffer)
> +{
> +	struct io_cgroup *iocg;
> +	struct io_policy_node *newpn, *pn;
> +	char *buf;
> +	int ret = 0;
> +	int keep_newpn = 0;
> +	struct hlist_node *n;
> +	struct io_group *iog;
> +
> +	buf = kstrdup(buffer, GFP_KERNEL);
> +	if (!buf)
> +		return -ENOMEM;
> +
> +	newpn = kzalloc(sizeof(*newpn), GFP_KERNEL);
> +	if (!newpn) {
> +		ret = -ENOMEM;
> +		goto free_buf;
> +	}
> +
> +	ret = policy_parse_and_set(buf, newpn);
> +	if (ret)
> +		goto free_newpn;
> +
> +	if (!cgroup_lock_live_group(cgrp)) {
> +		ret = -ENODEV;
> +		goto free_newpn;
> +	}
> +
> +	iocg = cgroup_to_io_cgroup(cgrp);
> +	spin_lock_irq(&iocg->lock);
> +
> +	pn = policy_search_node(iocg, newpn->dev);
> +	if (!pn) {
> +		if (newpn->weight != 0) {
> +			policy_insert_node(iocg, newpn);
> +			keep_newpn = 1;
> +		}
> +		goto update_io_group;
> +	}
> +
> +	if (newpn->weight == 0) {
> +		/* weight == 0 means deleteing a policy */
> +		policy_delete_node(pn);
> +		goto update_io_group;
> +	}
> +
> +	pn->weight = newpn->weight;
> +	pn->ioprio_class = newpn->ioprio_class;
> +
> +update_io_group:
> +	hlist_for_each_entry(iog, n, &iocg->group_data, group_node) {
> +		if (iog->dev == newpn->dev) {
> +			if (newpn->weight) {
> +				iog->entity.new_weight = newpn->weight;
> +				iog->entity.new_ioprio_class =
> +					newpn->ioprio_class;
> +				/*
> +				 * iog weight and ioprio_class updating
> +				 * actually happens if ioprio_changed is set.
> +				 * So ensure ioprio_changed is not set until
> +				 * new weight and new ioprio_class are updated.
> +				 */
> +				smp_wmb();
> +				iog->entity.ioprio_changed = 1;
> +			} else {
> +				iog->entity.new_weight = iocg->weight;
> +				iog->entity.new_ioprio_class =
> +					iocg->ioprio_class;
> +
> +				/* The same as above */
> +				smp_wmb();
> +				iog->entity.ioprio_changed = 1;
> +			}
> +		}
> +	}
> +	spin_unlock_irq(&iocg->lock);
> +
> +	cgroup_unlock();
> +
> +free_newpn:
> +	if (!keep_newpn)
> +		kfree(newpn);
> +free_buf:
> +	kfree(buf);
> +	return ret;
> +}
> +
>  struct cftype bfqio_files[] = {
>  	{
> +		.name = "policy",
> +		.read_seq_string = io_cgroup_policy_read,
> +		.write_string = io_cgroup_policy_write,
> +		.max_write_len = 256,
> +	},
> +	{
>  		.name = "weight",
>  		.read_u64 = io_cgroup_weight_read,
>  		.write_u64 = io_cgroup_weight_write,
> @@ -1592,6 +1824,7 @@ struct cgroup_subsys_state *iocg_create(struct cgroup_subsys *subsys,
>  	INIT_HLIST_HEAD(&iocg->group_data);
>  	iocg->weight = IO_DEFAULT_GRP_WEIGHT;
>  	iocg->ioprio_class = IO_DEFAULT_GRP_CLASS;
> +	INIT_LIST_HEAD(&iocg->policy_list);
>  
>  	return &iocg->css;
>  }
> @@ -1750,6 +1983,7 @@ void iocg_destroy(struct cgroup_subsys *subsys, struct cgroup *cgroup)
>  	unsigned long flags, flags1;
>  	int queue_lock_held = 0;
>  	struct elv_fq_data *efqd;
> +	struct io_policy_node *pn, *pntmp;
>  
>  	/*
>  	 * io groups are linked in two lists. One list is maintained
> @@ -1823,6 +2057,12 @@ locked:
>  	BUG_ON(!hlist_empty(&iocg->group_data));
>  
>  	free_css_id(&io_subsys, &iocg->css);
> +
> +	list_for_each_entry_safe(pn, pntmp, &iocg->policy_list, node) {
> +		policy_delete_node(pn);
> +		kfree(pn);
> +	}
> +
>  	kfree(iocg);
>  }
>  
> diff --git a/block/elevator-fq.h b/block/elevator-fq.h
> index db3a347..b1d97e6 100644
> --- a/block/elevator-fq.h
> +++ b/block/elevator-fq.h
> @@ -250,9 +250,18 @@ struct io_group {
>  
>  #ifdef CONFIG_DEBUG_GROUP_IOSCHED
>  	unsigned short iocg_id;
> +	dev_t dev;
>  #endif
>  };
>  
> +struct io_policy_node {
> +	struct list_head node;
> +	char dev_name[32];
> +	dev_t dev;
> +	unsigned long weight;
> +	unsigned long ioprio_class;
> +};
> +
>  /**
>   * struct bfqio_cgroup - bfq cgroup data structure.
>   * @css: subsystem state for bfq in the containing cgroup.
> @@ -269,6 +278,9 @@ struct io_cgroup {
>  
>  	unsigned long weight, ioprio_class;
>  
> +	/* list of io_policy_node */
> +	struct list_head policy_list;
> +
>  	spinlock_t lock;
>  	struct hlist_head group_data;
>  };
> -- 
> 1.5.4.rc3
> 
> 
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