Messages in this thread | | | Date | Thu, 03 Apr 2008 18:13:13 +0800 | From | Li Zefan <> | Subject | Re: [PATCH -mm 1/3] cgroup: use a hash table for css_set finding |
| |
>>> +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]; >>> + >> maybe css[i]'s lower 2-3 bits will be ignored. because thery are always 0. >> >> And I don't like "+" for hash. how about >> == >> for (i = 0; i < CGROUP_SUBSYS_COUNT; i++) >> unsigned long x; >> x = (unsigned long)css[i]; >> tmp = (x >> 16) ^ (x & 0xffff) >> == >> or some func, which uses full bits. >> > > I'm using hash_long(), which has been proved to be a good one. And I've tested > css_set_hash(), I run the css_set benchmark with N == 1000, the for loop in > find_existing_css_set() will break out within 10 iterations for most cases, > which is the expected result. >
I just revised the css_set_hash() a bit, and It turned out we can improve the scalability.
Thanks, KAMEZAWA-san.
| |