[Devel] Re: [PATCH -mm 3/3] cgroup: remove the css_set linked-list

[Paul Menage]

On Wed, Apr 2, 2008 at 10:53 PM, Li Zefan <lizf at cn.fujitsu.com> wrote:
> Now we can run through the hash table instead of running through
>  the linked-list.
>
>  Signed-off-by: Li Zefan <lizf at cn.fujitsu.com>

Reviewed-by: Paul Menage <menage at google.com>

Looks good, thanks.

>  ---
>   include/linux/cgroup.h |    6 ------
>   kernel/cgroup.c        |   40 ++++++++++++++++++++--------------------
>   2 files changed, 20 insertions(+), 26 deletions(-)
>
>  diff --git a/include/linux/cgroup.h b/include/linux/cgroup.h
>  index f585b7c..d58a958 100644
>  --- a/include/linux/cgroup.h
>  +++ b/include/linux/cgroup.h
>  @@ -150,12 +150,6 @@ struct css_set {
>         struct kref ref;
>
>         /*
>  -        * List running through all cgroup groups. Protected by
>  -        * css_set_lock
>  -        */
>  -       struct list_head list;
>  -
>  -       /*
>          * List running through all cgroup groups in the same hash
>          * slot. Protected by css_set_lock
>          */
>  diff --git a/kernel/cgroup.c b/kernel/cgroup.c
>  index 250e28e..9e7cf16 100644
>  --- a/kernel/cgroup.c
>  +++ b/kernel/cgroup.c
>  @@ -241,7 +241,6 @@ static void unlink_css_set(struct css_set *cg)
>   {
>         write_lock(&css_set_lock);
>         hlist_del(&cg->hlist);
>  -       list_del(&cg->list);
>         css_set_count--;
>         while (!list_empty(&cg->cg_links)) {
>                 struct cg_cgroup_link *link;
>  @@ -476,8 +475,6 @@ static struct css_set *find_css_set(
>
>         BUG_ON(!list_empty(&tmp_cg_links));
>
>  -       /* Link this cgroup group into the list */
>  -       list_add(&res->list, &init_css_set.list);
>         css_set_count++;
>
>         /* Add this cgroup group to the hash table */
>  @@ -962,7 +959,7 @@ static int cgroup_get_sb(struct file_system_type *fs_type,
>         int ret = 0;
>         struct super_block *sb;
>         struct cgroupfs_root *root;
>  -       struct list_head tmp_cg_links, *l;
>  +       struct list_head tmp_cg_links;
>         INIT_LIST_HEAD(&tmp_cg_links);
>
>         /* First find the desired set of subsystems */
>  @@ -1004,6 +1001,7 @@ static int cgroup_get_sb(struct file_system_type *fs_type,
>                 /* New superblock */
>                 struct cgroup *cgrp = &root->top_cgroup;
>                 struct inode *inode;
>  +               int i;
>
>                 BUG_ON(sb->s_root != NULL);
>
>  @@ -1048,22 +1046,25 @@ static int cgroup_get_sb(struct file_system_type *fs_type,
>                 /* Link the top cgroup in this hierarchy into all
>                  * the css_set objects */
>                 write_lock(&css_set_lock);
>  -               l = &init_css_set.list;
>  -               do {
>  +               for (i = 0; i < CSS_SET_TABLE_SIZE; i++) {
>  +                       struct hlist_head *hhead = &css_set_table[i];
>  +                       struct hlist_node *node;
>                         struct css_set *cg;
>  -                       struct cg_cgroup_link *link;
>  -                       cg = list_entry(l, struct css_set, list);
>  -                       BUG_ON(list_empty(&tmp_cg_links));
>  -                       link = list_entry(tmp_cg_links.next,
>  -                                         struct cg_cgroup_link,
>  -                                         cgrp_link_list);
>  -                       list_del(&link->cgrp_link_list);
>  -                       link->cg = cg;
>  -                       list_add(&link->cgrp_link_list,
>  -                                &root->top_cgroup.css_sets);
>  -                       list_add(&link->cg_link_list, &cg->cg_links);
>  -                       l = l->next;
>  -               } while (l != &init_css_set.list);
>  +
>  +                       hlist_for_each_entry(cg, node, hhead, hlist) {
>  +                               struct cg_cgroup_link *link;
>  +
>  +                               BUG_ON(list_empty(&tmp_cg_links));
>  +                               link = list_entry(tmp_cg_links.next,
>  +                                                 struct cg_cgroup_link,
>  +                                                 cgrp_link_list);
>  +                               list_del(&link->cgrp_link_list);
>  +                               link->cg = cg;
>  +                               list_add(&link->cgrp_link_list,
>  +                                        &root->top_cgroup.css_sets);
>  +                               list_add(&link->cg_link_list, &cg->cg_links);
>  +                       }
>  +               }
>                 write_unlock(&css_set_lock);
>
>                 free_cg_links(&tmp_cg_links);
>  @@ -2508,7 +2509,6 @@ int __init cgroup_init_early(void)
>         int i;
>         kref_init(&init_css_set.ref);
>         kref_get(&init_css_set.ref);
>  -       INIT_LIST_HEAD(&init_css_set.list);
>         INIT_LIST_HEAD(&init_css_set.cg_links);
>         INIT_LIST_HEAD(&init_css_set.tasks);
>         INIT_HLIST_NODE(&init_css_set.hlist);
>  --
>  1.5.4.rc3
>
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