[RFC PATCH -mm 2/2] cgroup: fold struct cg_cgroup_link into structcss_set
From: Lai Jiangshan
Date: Thu Sep 11 2008 - 10:26:23 EST
one struct cg_cgroup_link per link is very waste.
This way need to allocate struct cg_cgroup_link for
(css_set_count * hierarchy_count) times. And it will bring fragments
for memory allocation.
This patch fold struct cg_cgroup_link into struct css_set, use
cgroup_link[hierarchy_id] for every hierarchy's cgroup's link.
This patch removes lots of line of code. remove struct cg_cgroup_link
and corresponding code.
Signed-off-by: Lai Jiangshan <laijs@xxxxxxxxxxxxxx>
---
diff --git a/include/linux/cgroup.h b/include/linux/cgroup.h
index 4f281c5..f4ec055 100644
--- a/include/linux/cgroup.h
+++ b/include/linux/cgroup.h
@@ -173,18 +173,18 @@ struct css_set {
struct list_head tasks;
/*
- * List of cg_cgroup_link objects on link chains from
- * cgroups referenced from this css_set. Protected by
- * css_set_lock
- */
- struct list_head cg_links;
-
- /*
* Set of subsystem states, one for each subsystem. This array
* is immutable after creation apart from the init_css_set
* during subsystem registration (at boot time).
*/
struct cgroup_subsys_state *subsys[CGROUP_SUBSYS_COUNT];
+
+ /*
+ * List running through cgroup_link[hierarchy_id] associated with a
+ * cgroup of the corresponding hierarchy, anchored on
+ * cgroup->css_sets. Protected by css_set_lock.
+ */
+ struct list_head cgroup_link[CGROUP_SUBSYS_COUNT];
};
/*
diff --git a/kernel/cgroup.c b/kernel/cgroup.c
index 4bd5560..6c833d1 100644
--- a/kernel/cgroup.c
+++ b/kernel/cgroup.c
@@ -227,21 +227,6 @@ static void cgroup_release_agent(struct work_struct *work);
static DECLARE_WORK(release_agent_work, cgroup_release_agent);
static void check_for_release(struct cgroup *cgrp);
-/* Link structure for associating css_set objects with cgroups */
-struct cg_cgroup_link {
- /*
- * List running through cg_cgroup_links associated with a
- * cgroup, anchored on cgroup->css_sets
- */
- struct list_head cgrp_link_list;
- /*
- * List running through cg_cgroup_links pointing at a
- * single css_set object, anchored on css_set->cg_links
- */
- struct list_head cg_link_list;
- struct css_set *cg;
-};
-
/* The default css_set - used by init and its children prior to any
* hierarchies being mounted. It contains a pointer to the root state
* for each subsystem. Also used to anchor the list of css_sets. Not
@@ -250,7 +235,6 @@ struct cg_cgroup_link {
*/
static struct css_set init_css_set;
-static struct cg_cgroup_link init_css_set_link;
/* css_set_lock protects the list of css_set objects, and the
* chain of tasks off each css_set. Nests outside task->alloc_lock
@@ -304,18 +288,13 @@ static int use_task_css_set_links __read_mostly;
*/
static void unlink_css_set(struct css_set *cg)
{
- struct cg_cgroup_link *link;
- struct cg_cgroup_link *saved_link;
+ int i;
+ for (i = 0; i < CGROUP_SUBSYS_COUNT; i++)
+ if (!list_empty(&cg->cgroup_link[i]))
+ list_del(&cg->cgroup_link[i]);
hlist_del(&cg->hlist);
css_set_count--;
-
- list_for_each_entry_safe(link, saved_link, &cg->cg_links,
- cg_link_list) {
- list_del(&link->cg_link_list);
- list_del(&link->cgrp_link_list);
- kfree(link);
- }
}
static void __put_css_set(struct css_set *cg, int taskexit)
@@ -419,38 +398,6 @@ static struct css_set *find_existing_css_set(
return NULL;
}
-static void free_cg_links(struct list_head *tmp)
-{
- struct cg_cgroup_link *link;
- struct cg_cgroup_link *saved_link;
-
- list_for_each_entry_safe(link, saved_link, tmp, cgrp_link_list) {
- list_del(&link->cgrp_link_list);
- kfree(link);
- }
-}
-
-/*
- * allocate_cg_links() allocates "count" cg_cgroup_link structures
- * and chains them on tmp through their cgrp_link_list fields. Returns 0 on
- * success or a negative error
- */
-static int allocate_cg_links(int count, struct list_head *tmp)
-{
- struct cg_cgroup_link *link;
- int i;
- INIT_LIST_HEAD(tmp);
- for (i = 0; i < count; i++) {
- link = kmalloc(sizeof(*link), GFP_KERNEL);
- if (!link) {
- free_cg_links(tmp);
- return -ENOMEM;
- }
- list_add(&link->cgrp_link_list, tmp);
- }
- return 0;
-}
-
/*
* find_css_set() takes an existing cgroup group and a
* cgroup object, and returns a css_set object that's
@@ -465,9 +412,6 @@ static struct css_set *find_css_set(
struct cgroup_subsys_state *template[CGROUP_SUBSYS_COUNT];
int i;
- struct list_head tmp_cg_links;
- struct cg_cgroup_link *link;
-
struct hlist_head *hhead;
/* First see if we already have a cgroup group that matches
@@ -485,16 +429,11 @@ static struct css_set *find_css_set(
if (!res)
return NULL;
- /* Allocate all the cg_cgroup_link objects that we'll need */
- if (allocate_cg_links(root_count, &tmp_cg_links) < 0) {
- kfree(res);
- return NULL;
- }
-
atomic_set(&res->refcount, 1);
- INIT_LIST_HEAD(&res->cg_links);
INIT_LIST_HEAD(&res->tasks);
INIT_HLIST_NODE(&res->hlist);
+ for (i = 0; i < CGROUP_SUBSYS_COUNT; i++)
+ INIT_LIST_HEAD(&res->cgroup_link[i]);
/* Copy the set of subsystem state objects generated in
* find_existing_css_set() */
@@ -512,28 +451,15 @@ static struct css_set *find_css_set(
* hierarchy
*/
if (ss->root->subsys_list.next == &ss->sibling) {
- 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);
- list_add(&link->cgrp_link_list, &cgrp->css_sets);
- link->cg = res;
- list_add(&link->cg_link_list, &res->cg_links);
+ list_add(&res->cgroup_link[ss->root->hierarchy_id],
+ &cgrp->css_sets);
}
}
if (list_empty(&rootnode.subsys_list)) {
- link = list_entry(tmp_cg_links.next,
- struct cg_cgroup_link,
- cgrp_link_list);
- list_del(&link->cgrp_link_list);
- list_add(&link->cgrp_link_list, &dummytop->css_sets);
- link->cg = res;
- list_add(&link->cg_link_list, &res->cg_links);
+ list_add(&res->cgroup_link[rootnode.hierarchy_id],
+ &dummytop->css_sets);
}
- BUG_ON(!list_empty(&tmp_cg_links));
-
css_set_count++;
/* Add this cgroup group to the hash table */
@@ -1019,7 +945,6 @@ 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;
/* First find the desired set of subsystems */
ret = parse_cgroupfs_options(data, &opts);
@@ -1072,20 +997,6 @@ static int cgroup_get_sb(struct file_system_type *fs_type,
mutex_lock(&inode->i_mutex);
mutex_lock(&cgroup_mutex);
- /*
- * We're accessing css_set_count without locking
- * css_set_lock here, but that's OK - it can only be
- * increased by someone holding cgroup_lock, and
- * that's us. The worst that can happen is that we
- * have some link structures left over
- */
- ret = allocate_cg_links(css_set_count, &tmp_cg_links);
- if (ret) {
- mutex_unlock(&cgroup_mutex);
- mutex_unlock(&inode->i_mutex);
- goto drop_new_super;
- }
-
ret = rebind_subsystems(root, root->subsys_bits);
if (ret == -EBUSY) {
mutex_unlock(&cgroup_mutex);
@@ -1112,23 +1023,12 @@ static int cgroup_get_sb(struct file_system_type *fs_type,
struct css_set *cg;
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,
+ list_add(&cg->cgroup_link[root->hierarchy_id],
&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);
-
BUG_ON(!list_empty(&cgrp->sibling));
BUG_ON(!list_empty(&cgrp->children));
BUG_ON(root->number_of_cgroups != 1);
@@ -1143,7 +1043,6 @@ static int cgroup_get_sb(struct file_system_type *fs_type,
drop_new_super:
up_write(&sb->s_umount);
deactivate_super(sb);
- free_cg_links(&tmp_cg_links);
return ret;
}
@@ -1151,8 +1050,7 @@ static void cgroup_kill_sb(struct super_block *sb) {
struct cgroupfs_root *root = sb->s_fs_info;
struct cgroup *cgrp = &root->top_cgroup;
int ret;
- struct cg_cgroup_link *link;
- struct cg_cgroup_link *saved_link;
+ struct list_head *pos, *next_save;
BUG_ON(!root);
@@ -1172,13 +1070,8 @@ static void cgroup_kill_sb(struct super_block *sb) {
* root cgroup
*/
write_lock(&css_set_lock);
-
- list_for_each_entry_safe(link, saved_link, &cgrp->css_sets,
- cgrp_link_list) {
- list_del(&link->cg_link_list);
- list_del(&link->cgrp_link_list);
- kfree(link);
- }
+ list_for_each_safe(pos, next_save, &cgrp->css_sets)
+ list_del_init(pos);
write_unlock(&css_set_lock);
if (!list_empty(&root->root_list)) {
@@ -1795,12 +1688,12 @@ int cgroup_add_files(struct cgroup *cgrp,
int cgroup_task_count(const struct cgroup *cgrp)
{
int count = 0;
- struct cg_cgroup_link *link;
+ int index = cgrp->root->hierarchy_id;
+ struct css_set *cg;
read_lock(&css_set_lock);
- list_for_each_entry(link, &cgrp->css_sets, cgrp_link_list) {
- count += atomic_read(&link->cg->refcount);
- }
+ list_for_each_entry(cg, &cgrp->css_sets, cgroup_link[index])
+ count += atomic_read(&cg->refcount);
read_unlock(&css_set_lock);
return count;
}
@@ -1813,7 +1706,7 @@ static void cgroup_advance_iter(struct cgroup *cgrp,
struct cgroup_iter *it)
{
struct list_head *l = it->cg_link;
- struct cg_cgroup_link *link;
+ int index = cgrp->root->hierarchy_id;
struct css_set *cg;
/* Advance to the next non-empty css_set */
@@ -1823,8 +1716,7 @@ static void cgroup_advance_iter(struct cgroup *cgrp,
it->cg_link = NULL;
return;
}
- link = list_entry(l, struct cg_cgroup_link, cgrp_link_list);
- cg = link->cg;
+ cg = list_entry(l, struct css_set, cgroup_link[index]);
} while (list_empty(&cg->tasks));
it->cg_link = l;
it->task = cg->tasks.next;
@@ -1887,7 +1779,7 @@ struct task_struct *cgroup_iter_next(struct cgroup *cgrp,
l = l->next;
if (l == &res->cgroups->tasks) {
/* We reached the end of this task list - move on to
- * the next cg_cgroup_link */
+ * the next css_set */
cgroup_advance_iter(cgrp, it);
} else {
it->task = l;
@@ -2640,9 +2532,10 @@ int __init cgroup_init_early(void)
{
int i;
atomic_set(&init_css_set.refcount, 1);
- INIT_LIST_HEAD(&init_css_set.cg_links);
INIT_LIST_HEAD(&init_css_set.tasks);
INIT_HLIST_NODE(&init_css_set.hlist);
+ for (i = 0; i < CGROUP_SUBSYS_COUNT; i++)
+ INIT_LIST_HEAD(&init_css_set.cgroup_link[i]);
css_set_count = 1;
init_cgroup_root(&rootnode);
list_add(&rootnode.root_list, &roots);
@@ -2650,11 +2543,8 @@ int __init cgroup_init_early(void)
root_count = 1;
init_task.cgroups = &init_css_set;
- init_css_set_link.cg = &init_css_set;
- list_add(&init_css_set_link.cgrp_link_list,
+ list_add(&init_css_set.cgroup_link[rootnode.hierarchy_id],
&rootnode.top_cgroup.css_sets);
- list_add(&init_css_set_link.cg_link_list,
- &init_css_set.cg_links);
for (i = 0; i < CSS_SET_TABLE_SIZE; i++)
INIT_HLIST_HEAD(&css_set_table[i]);
--
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