On Wed, 21 Jul 2010 19:58:31 +0900
KAMEZAWA Hiroyuki <kamezawa.hiroyu@xxxxxxxxxxxxxx> wrote:
> These are just a _toy_ level patches yet. My final purpose is to use indexed array
> for mem_cgroup itself, it has IDs.
>
> Background:
> memory cgroup uses struct page_cgroup for tracking all used pages. It's defined as
> ==
> struct page_cgroup {
> unsigned long flags;
> struct mem_cgroup *mem_cgroup;
> struct page *page;
> struct list_head lru; /* per cgroup LRU list */
> };
> ==
> and this increase the cost of per-page-objects dramatically. Now, we have
> troubles on this object.
> 1. Recently, a blkio-tracking guy wants to add "blockio-cgroup" information
> to page_cgroup. But our concern is extra 8bytes per page.
> 2. At tracking dirty page status etc...we need some trick for safe access
> to page_cgroup and memcgroup's information. For example, a small seqlock.
>
> Now, each memory cgroup has its own ID (0-65535). So, if we can replace
> 8byte of pointer "pc->mem_cgroup" with an ID, which is 2 bytes, we may able
> to have another room. (Moreover, I think we can reduce the number of IDs...)
>
> This patch is a trial for implement a virually-indexed on-demand array and
> an example of usage. Any commetns are welcome.
>
So, your purpose is to:
- make the size of mem_croup small(by [2/2])
- manage all the mem_cgroup in virt-array indexed by its ID(it would be faster
than using css_lookup)
- replace pc->mem_cgroup by its ID and make the size of page_cgroup small
right?
Thanks,
Daisuke Nishimura.
--
To unsubscribe, send a message with 'unsubscribe linux-mm' in
the body to majordomo@xxxxxxxxxx For more info on Linux MM,
see: http://www.linux-mm.org/ .
Don't email: <a href=mailto:"dont@xxxxxxxxx";> email@xxxxxxxxx </a>