Message-ID: <4B8EFEF5.2020809@cn.fujitsu.com>
Date:	Thu, 04 Mar 2010 08:29:41 +0800
From:	Gui Jianfeng <guijianfeng@...fujitsu.com>
To:	Vivek Goyal <vgoyal@...hat.com>
CC:	Jens Axboe <jens.axboe@...cle.com>,
	linux kernel mailing list <linux-kernel@...r.kernel.org>
Subject: Re: [PATCH 2/1] io-controller: Add a new interface "policy" for IO
 Controller

Vivek Goyal wrote:
> On Wed, Mar 03, 2010 at 02:21:11PM +0800, Gui Jianfeng wrote:
>> Currently, IO Controller makes use of blkio.weight to assign weight for
>> all devices. Here a new user interface "blkio.policy" is introduced to 
>> assign different weights for different devices. blkio.weight becomes the
>> default value for devices which are not configured by blkio.policy.
>>
>> You can use the following format to assigned specific weight for a given
>> device:
>> #echo "major:minor weight" > blkio.policy
>>
>> major:minor represents device number.
>>
>> And you can remove a policy as following:
>> #echo "major:minor 0" > blkio.policy
>>
>> Signed-off-by: Gui Jianfeng <guijianfeng@...fujitsu.com>
>> ---
>>  block/blk-cgroup.c  |  248 +++++++++++++++++++++++++++++++++++++++++++++++++++
>>  block/blk-cgroup.h  |    9 ++
>>  block/cfq-iosched.c |    2 +-
>>  3 files changed, 258 insertions(+), 1 deletions(-)
>>
>> diff --git a/block/blk-cgroup.c b/block/blk-cgroup.c
>> index e7dbbaf..1fddb98 100644
>> --- a/block/blk-cgroup.c
>> +++ b/block/blk-cgroup.c
>> @@ -16,6 +16,7 @@
>>  #include <linux/module.h>
>>  #include <linux/err.h>
>>  #include "blk-cgroup.h"
>> +#include <linux/genhd.h>
>>  
>>  static DEFINE_SPINLOCK(blkio_list_lock);
>>  static LIST_HEAD(blkio_list);
>> @@ -23,6 +24,12 @@ static LIST_HEAD(blkio_list);
>>  struct blkio_cgroup blkio_root_cgroup = { .weight = 2*BLKIO_WEIGHT_DEFAULT };
>>  EXPORT_SYMBOL_GPL(blkio_root_cgroup);
>>  
>> +static inline void policy_insert_node(struct blkio_cgroup *blkcg,
>> +				      struct io_policy_node *pn);
> 					     ^^^^^^^^^^
> How about blkio_policy_node?
> 
> So this structure will represent per cgroup per device policy as specified
> by user. We can re-use the same structure if there are more per cgroup
> per device policies down the line. 
> 
>> +static inline void policy_delete_node(struct io_policy_node *pn);
>> +static struct io_policy_node *policy_search_node(const struct blkio_cgroup *blkcg,
>> +						 dev_t dev);
> 
> Not very sure about it but may be a good idea to prefix "blkio_" or
> "blkcg_" before all the functions you are defining. Just some uniformity in
> function names like cfq.
> 
>> +
>>  bool blkiocg_css_tryget(struct blkio_cgroup *blkcg)
> 
> You might want to rebase it on Jen's for-linus branch as blkiocg_css_tryget()
> is gone in that branch
> 
> Apart from above minor nits, this patch looks good to me. Will do some
> testing on it.

Thanks for the comments vivek, will post V2.

Thanks
Gui

> 
> Thanks
> Vivek
> 
>>  {
>>  	if (!css_tryget(&blkcg->css))
>> @@ -142,6 +149,7 @@ blkiocg_weight_write(struct cgroup *cgroup, struct cftype *cftype, u64 val)
>>  	struct blkio_group *blkg;
>>  	struct hlist_node *n;
>>  	struct blkio_policy_type *blkiop;
>> +	struct io_policy_node *pn;
>>  
>>  	if (val < BLKIO_WEIGHT_MIN || val > BLKIO_WEIGHT_MAX)
>>  		return -EINVAL;
>> @@ -150,7 +158,13 @@ blkiocg_weight_write(struct cgroup *cgroup, struct cftype *cftype, u64 val)
>>  	spin_lock(&blkio_list_lock);
>>  	spin_lock_irq(&blkcg->lock);
>>  	blkcg->weight = (unsigned int)val;
>> +
>>  	hlist_for_each_entry(blkg, n, &blkcg->blkg_list, blkcg_node) {
>> +		pn = policy_search_node(blkcg, blkg->dev);
>> +
>> +		if (pn)
>> +			continue;
> 
> Ok, so if we have specified a weight for a device, then blkio.weight
> update does not affect the weight on that device. Makes sense.
> 
>> +
>>  		list_for_each_entry(blkiop, &blkio_list, list)
>>  			blkiop->ops.blkio_update_group_weight_fn(blkg,
>>  					blkcg->weight);
>> @@ -199,8 +213,235 @@ void blkiocg_update_blkio_group_dequeue_stats(struct blkio_group *blkg,
>>  EXPORT_SYMBOL_GPL(blkiocg_update_blkio_group_dequeue_stats);
>>  #endif
>>  
>> +static int check_dev_num(dev_t dev)
>> +{
>> +	int part = 0;
>> +	struct gendisk *disk;
>> +
>> +	disk = get_gendisk(dev, &part);
>> +
>> +	if (!disk || part)
>> +		return -ENODEV;
>> +
>> +	return 0;
>> +}
>> +
>> +static int policy_parse_and_set(char *buf, struct io_policy_node *newpn)
>> +{
>> +	char *s[4], *p, *major_s = NULL, *minor_s = NULL;
>> +	int ret;
>> +	unsigned long major, minor, temp;
>> +	int i = 0;
>> +	dev_t dev;
>> +
>> +	memset(s, 0, sizeof(s));
>> +
>> +	while ((p = strsep(&buf, " ")) != NULL) {
>> +		if (!*p)
>> +			continue;
>> +
>> +		s[i++] = p;
>> +
>> +		/* Prevent from inputing too many things */
>> +		if (i == 3)
>> +			break;
>> +	}
>> +
>> +	if (i != 2)
>> +		return -EINVAL;
>> +
>> +	p = strsep(&s[0], ":");
>> +
>> +	if (p != NULL)
>> +		major_s = p;
>> +	else
>> +		return -EINVAL;
>> +
>> +	minor_s = s[0];
>> +
>> +	if (!minor_s)
>> +		return -EINVAL;
>> +
>> +	ret = strict_strtoul(major_s, 10, &major);
>> +	if (ret)
>> +		return -EINVAL;
>> +
>> +	ret = strict_strtoul(minor_s, 10, &minor);
>> +	if (ret)
>> +		return -EINVAL;
>> +
>> +	dev = MKDEV(major, minor);
>> +
>> +	ret = check_dev_num(dev);
>> +	if (ret)
>> +		return ret;
>> +
>> +	newpn->dev = dev;
>> +
>> +	if (s[1] == NULL)
>> +		return -EINVAL;
>> +
>> +	ret = strict_strtoul(s[1], 10, &temp);
>> +	if (ret || (temp < BLKIO_WEIGHT_MIN && temp > 0) ||
>> +	    temp > BLKIO_WEIGHT_MAX)
>> +		return -EINVAL;
>> +
>> +	newpn->weight =  temp;
>> +
>> +	return 0;
>> +}
>> +
>> +unsigned int blkcg_get_weight(struct blkio_cgroup *blkcg,
>> +				    dev_t dev)
>> +{
>> +	struct io_policy_node *pn;
>> +
>> +	pn = policy_search_node(blkcg, dev);
>> +
>> +	if (pn)
>> +		return pn->weight;
>> +	else
>> +		return blkcg->weight;
>> +}
>> +EXPORT_SYMBOL_GPL(blkcg_get_weight);
>> +
>> +static inline void policy_insert_node(struct blkio_cgroup *blkcg,
>> +				      struct io_policy_node *pn)
>> +{
>> +	list_add(&pn->node, &blkcg->policy_list);
>> +}
>> +
>> +/* Must be called with blkcg->lock held */
>> +static inline void policy_delete_node(struct io_policy_node *pn)
>> +{
>> +	list_del(&pn->node);
>> +}
>> +
>> +/* Must be called with blkcg->lock held */
>> +static struct io_policy_node *policy_search_node(const struct blkio_cgroup *blkcg,
>> +						 dev_t dev)
>> +{
>> +	struct io_policy_node *pn;
>> +
>> +	if (list_empty(&blkcg->policy_list))
>> +		return NULL;
>> +
>> +	list_for_each_entry(pn, &blkcg->policy_list, node) {
>> +		if (pn->dev == dev)
>> +			return pn;
>> +	}
>> +
>> +	return NULL;
>> +}
>> +
>> +
>> +static int blkiocg_policy_write(struct cgroup *cgrp, struct cftype *cft,
>> +				const char *buffer)
>> +{
>> +	int ret = 0;
>> +	char *buf;
>> +	struct io_policy_node *newpn, *pn;
>> +	struct blkio_cgroup *blkcg;
>> +	struct blkio_group *blkg;
>> +	int keep_newpn = 0;
>> +	struct hlist_node *n;
>> +	struct blkio_policy_type *blkiop;
>> +
>> +	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;
>> +
>> +	blkcg = cgroup_to_blkio_cgroup(cgrp);
>> +
>> +	spin_lock_irq(&blkcg->lock);
>> +
>> +	pn = policy_search_node(blkcg, newpn->dev);
>> +	if (!pn) {
>> +		if (newpn->weight != 0) {
>> +			policy_insert_node(blkcg, newpn);
>> +			keep_newpn = 1;
>> +		}
>> +		spin_unlock_irq(&blkcg->lock);
>> +		goto update_io_group;
>> +	}
>> +
>> +	if (newpn->weight == 0) {
>> +		/* weight == 0 means deleteing a policy */
>> +		policy_delete_node(pn);
>> +		spin_unlock_irq(&blkcg->lock);
>> +		goto update_io_group;
>> +	}
>> +	spin_unlock_irq(&blkcg->lock);
>> +
>> +	pn->weight = newpn->weight;
>> +
>> +update_io_group:
>> +	/* update weight for each cfqg */
>> +	spin_lock(&blkio_list_lock);
>> +	spin_lock_irq(&blkcg->lock);
>> +
>> +	hlist_for_each_entry(blkg, n, &blkcg->blkg_list, blkcg_node) {
>> +		if (newpn->dev == blkg->dev) {
>> +			list_for_each_entry(blkiop, &blkio_list, list)
>> +				blkiop->ops.blkio_update_group_weight_fn(blkg,
>> +						newpn->weight ?
>> +						newpn->weight :
>> +						blkcg->weight);
>> +		}
>> +	}
>> +
>> +	spin_unlock_irq(&blkcg->lock);
>> +	spin_unlock(&blkio_list_lock);
>> +
>> +free_newpn:
>> +	if (!keep_newpn)
>> +		kfree(newpn);
>> +free_buf:
>> +	kfree(buf);
>> +	return ret;
>> +}
>> +
>> +static int blkiocg_policy_read(struct cgroup *cgrp, struct cftype *cft,
>> +			       struct seq_file *m)
>> +{
>> +	struct blkio_cgroup *blkcg;
>> +	struct io_policy_node *pn;
>> +
>> +	blkcg = cgroup_to_blkio_cgroup(cgrp);
>> +
>> +	if (list_empty(&blkcg->policy_list))
>> +		goto out;
>> +
>> +	seq_printf(m, "dev\tweight\n");
>> +
>> +	spin_lock_irq(&blkcg->lock);
>> +	list_for_each_entry(pn, &blkcg->policy_list, node) {
>> +		seq_printf(m, "%u:%u\t%u\n", MAJOR(pn->dev),
>> +			   MINOR(pn->dev), pn->weight);
>> +	}
>> +	spin_unlock_irq(&blkcg->lock);
>> +out:
>> +	return 0;
>> +}
>> +
>>  struct cftype blkio_files[] = {
>>  	{
>> +		.name = "policy",
>> +		.read_seq_string = blkiocg_policy_read,
>> +		.write_string = blkiocg_policy_write,
>> +		.max_write_len = 256,
>> +	},
>> +	{
>>  		.name = "weight",
>>  		.read_u64 = blkiocg_weight_read,
>>  		.write_u64 = blkiocg_weight_write,
>> @@ -234,6 +475,7 @@ static void blkiocg_destroy(struct cgroup_subsys *subsys, struct cgroup *cgroup)
>>  	struct blkio_group *blkg;
>>  	void *key;
>>  	struct blkio_policy_type *blkiop;
>> +	struct io_policy_node *pn, *pntmp;
>>  
>>  	rcu_read_lock();
>>  remove_entry:
>> @@ -264,7 +506,12 @@ remove_entry:
>>  		blkiop->ops.blkio_unlink_group_fn(key, blkg);
>>  	spin_unlock(&blkio_list_lock);
>>  	goto remove_entry;
>> +
>>  done:
>> +	list_for_each_entry_safe(pn, pntmp, &blkcg->policy_list, node) {
>> +		policy_delete_node(pn);
>> +		kfree(pn);
>> +	}
>>  	free_css_id(&blkio_subsys, &blkcg->css);
>>  	rcu_read_unlock();
>>  	kfree(blkcg);
>> @@ -294,6 +541,7 @@ done:
>>  	spin_lock_init(&blkcg->lock);
>>  	INIT_HLIST_HEAD(&blkcg->blkg_list);
>>  
>> +	INIT_LIST_HEAD(&blkcg->policy_list);
>>  	return &blkcg->css;
>>  }
>>  
>> diff --git a/block/blk-cgroup.h b/block/blk-cgroup.h
>> index 4d316df..0551aa1 100644
>> --- a/block/blk-cgroup.h
>> +++ b/block/blk-cgroup.h
>> @@ -22,6 +22,7 @@ struct blkio_cgroup {
>>  	unsigned int weight;
>>  	spinlock_t lock;
>>  	struct hlist_head blkg_list;
>> +	struct list_head policy_list; /* list of io_policy_node */
>>  };
>>  
>>  struct blkio_group {
>> @@ -43,8 +44,16 @@ struct blkio_group {
>>  	unsigned long sectors;
>>  };
>>  
>> +struct io_policy_node {
>> +	struct list_head node;
>> +	dev_t dev;
>> +	unsigned int weight;
>> +};
>> +
>>  extern bool blkiocg_css_tryget(struct blkio_cgroup *blkcg);
>>  extern void blkiocg_css_put(struct blkio_cgroup *blkcg);
>> +extern unsigned int blkcg_get_weight(struct blkio_cgroup *blkcg,
>> +				     dev_t dev);
>>  
>>  typedef void (blkio_unlink_group_fn) (void *key, struct blkio_group *blkg);
>>  typedef void (blkio_update_group_weight_fn) (struct blkio_group *blkg,
>> diff --git a/block/cfq-iosched.c b/block/cfq-iosched.c
>> index 023f4e6..3d0dea1 100644
>> --- a/block/cfq-iosched.c
>> +++ b/block/cfq-iosched.c
>> @@ -963,7 +963,6 @@ cfq_find_alloc_cfqg(struct cfq_data *cfqd, struct cgroup *cgroup, int create)
>>  	if (!cfqg)
>>  		goto done;
>>  
>> -	cfqg->weight = blkcg->weight;
>>  	for_each_cfqg_st(cfqg, i, j, st)
>>  		*st = CFQ_RB_ROOT;
>>  	RB_CLEAR_NODE(&cfqg->rb_node);
>> @@ -980,6 +979,7 @@ cfq_find_alloc_cfqg(struct cfq_data *cfqd, struct cgroup *cgroup, int create)
>>  	sscanf(dev_name(bdi->dev), "%u:%u", &major, &minor);
>>  	blkiocg_add_blkio_group(blkcg, &cfqg->blkg, (void *)cfqd,
>>  					MKDEV(major, minor));
>> +	cfqg->weight = blkcg_get_weight(blkcg, cfqg->blkg.dev);
>>  
>>  	/* Add group on cfqd list */
>>  	hlist_add_head(&cfqg->cfqd_node, &cfqd->cfqg_list);
>> -- 
>> 1.5.4.rc3
> 
> 
> 

-- 
Regards
Gui Jianfeng

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