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SubjectRe: [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@cn.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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