Re: [PATCH] cgroup: use new hashtable implementation
From: Tejun Heo <hidden>
Date: 2013-01-08 18:17:36
Also in:
lkml
Hello, Li. On Tue, Jan 08, 2013 at 03:51:45PM +0800, Li Zefan wrote:
-static struct hlist_head *css_set_hash(struct cgroup_subsys_state *css[])
+static unsigned long css_set_hash(struct cgroup_subsys_state *css[])
{
int i;
- int index;
- unsigned long tmp = 0UL;
+ unsigned long key = 0UL;
for (i = 0; i < CGROUP_SUBSYS_COUNT; i++)
- tmp += (unsigned long)css[i];
- tmp = (tmp >> 16) ^ tmp;
+ key += (unsigned long)css[i];
+ key = (key >> 16) ^ key;@key is gonna go through hash function anyway. Do we still need the above (key >> 16) ^ key? It's not gonna help anything.
quoted hunk ↗ jump to hunk
- index = hash_long(tmp, CSS_SET_HASH_BITS); - - return &css_set_table[index]; + return key; } /* We don't maintain the lists running through each css_set to its@@ -4503,23 +4498,17 @@ int __init_or_module cgroup_load_subsys(struct cgroup_subsys *ss) * this is all done under the css_set_lock. */ write_lock(&css_set_lock); - for (i = 0; i < CSS_SET_TABLE_SIZE; i++) { - struct css_set *cg; - struct hlist_node *node, *tmp; - struct hlist_head *bucket = &css_set_table[i], *new_bucket; - - hlist_for_each_entry_safe(cg, node, tmp, bucket, hlist) { - /* skip entries that we already rehashed */ - if (cg->subsys[ss->subsys_id]) - continue; - /* remove existing entry */ - hlist_del(&cg->hlist); - /* set new value */ - cg->subsys[ss->subsys_id] = css; - /* recompute hash and restore entry */ - new_bucket = css_set_hash(cg->subsys); - hlist_add_head(&cg->hlist, new_bucket); - } + hash_for_each_safe(css_set_table, i, node, tmp, cg, hlist) { + /* skip entries that we already rehashed */ + if (cg->subsys[ss->subsys_id]) + continue; + /* remove existing entry */ + hlist_del(&cg->hlist);
hash_del()? Thanks. -- tejun