Re: [PATCH 2/1] io-controller: Add a new interface "policy" for IOController
From: Vivek Goyal
Date: Wed Mar 03 2010 - 10:36:52 EST
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@xxxxxxxxxxxxxx>
> ---
> 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
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
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