diff options
Diffstat (limited to 'kernel/cgroup.c')
| -rw-r--r-- | kernel/cgroup.c | 59 |
1 files changed, 47 insertions, 12 deletions
diff --git a/kernel/cgroup.c b/kernel/cgroup.c index 7c8cc514187..c447c29f874 100644 --- a/kernel/cgroup.c +++ b/kernel/cgroup.c @@ -44,6 +44,7 @@ #include <linux/kmod.h> #include <linux/delayacct.h> #include <linux/cgroupstats.h> +#include <linux/hash.h> #include <asm/atomic.h> @@ -193,6 +194,27 @@ static struct cg_cgroup_link init_css_set_link; static DEFINE_RWLOCK(css_set_lock); static int css_set_count; +/* hash table for cgroup groups. This improves the performance to + * find an existing css_set */ +#define CSS_SET_HASH_BITS 7 +#define CSS_SET_TABLE_SIZE (1 << CSS_SET_HASH_BITS) +static struct hlist_head css_set_table[CSS_SET_TABLE_SIZE]; + +static struct hlist_head *css_set_hash(struct cgroup_subsys_state *css[]) +{ + int i; + int index; + unsigned long tmp = 0UL; + + for (i = 0; i < CGROUP_SUBSYS_COUNT; i++) + tmp += (unsigned long)css[i]; + tmp = (tmp >> 16) ^ tmp; + + index = hash_long(tmp, CSS_SET_HASH_BITS); + + return &css_set_table[index]; +} + /* We don't maintain the lists running through each css_set to its * task until after the first call to cgroup_iter_start(). This * reduces the fork()/exit() overhead for people who have cgroups @@ -219,6 +241,7 @@ static int use_task_css_set_links; 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)) { @@ -284,9 +307,7 @@ static inline void put_css_set_taskexit(struct css_set *cg) /* * find_existing_css_set() is a helper for * find_css_set(), and checks to see whether an existing - * css_set is suitable. This currently walks a linked-list for - * simplicity; a later patch will use a hash table for better - * performance + * css_set is suitable. * * oldcg: the cgroup group that we're using before the cgroup * transition @@ -303,7 +324,9 @@ static struct css_set *find_existing_css_set( { int i; struct cgroupfs_root *root = cgrp->root; - struct list_head *l = &init_css_set.list; + struct hlist_head *hhead; + struct hlist_node *node; + struct css_set *cg; /* Built the set of subsystem state objects that we want to * see in the new css_set */ @@ -320,18 +343,13 @@ static struct css_set *find_existing_css_set( } } - /* Look through existing cgroup groups to find one to reuse */ - do { - struct css_set *cg = - list_entry(l, struct css_set, list); - + hhead = css_set_hash(template); + hlist_for_each_entry(cg, node, hhead, hlist) { if (!memcmp(template, cg->subsys, sizeof(cg->subsys))) { /* All subsystems matched */ return cg; } - /* Try the next cgroup group */ - l = l->next; - } while (l != &init_css_set.list); + } /* No existing cgroup group matched */ return NULL; @@ -393,6 +411,8 @@ static struct css_set *find_css_set( 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 * the desired set */ write_lock(&css_set_lock); @@ -417,6 +437,7 @@ static struct css_set *find_css_set( kref_init(&res->ref); INIT_LIST_HEAD(&res->cg_links); INIT_LIST_HEAD(&res->tasks); + INIT_HLIST_NODE(&res->hlist); /* Copy the set of subsystem state objects generated in * find_existing_css_set() */ @@ -459,6 +480,11 @@ static struct css_set *find_css_set( /* 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 */ + hhead = css_set_hash(res->subsys); + hlist_add_head(&res->hlist, hhead); + write_unlock(&css_set_lock); return res; @@ -2508,6 +2534,7 @@ int __init cgroup_init_early(void) 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); css_set_count = 1; init_cgroup_root(&rootnode); list_add(&rootnode.root_list, &roots); @@ -2520,6 +2547,9 @@ int __init cgroup_init_early(void) 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]); + for (i = 0; i < CGROUP_SUBSYS_COUNT; i++) { struct cgroup_subsys *ss = subsys[i]; @@ -2549,6 +2579,7 @@ int __init cgroup_init(void) { int err; int i; + struct hlist_head *hhead; err = bdi_init(&cgroup_backing_dev_info); if (err) @@ -2560,6 +2591,10 @@ int __init cgroup_init(void) cgroup_init_subsys(ss); } + /* Add init_css_set to the hash table */ + hhead = css_set_hash(init_css_set.subsys); + hlist_add_head(&init_css_set.hlist, hhead); + err = register_filesystem(&cgroup_fs_type); if (err < 0) goto out; |