On Tue, 27 Jul 2010 22:39:04 -0400
Vivek Goyal <vgoyal@xxxxxxxxxx> wrote:
> On Tue, Jul 27, 2010 at 04:56:29PM +0900, KAMEZAWA Hiroyuki wrote:
> > From: KAMEZAWA Hiroyuki <kamezawa.hiroyu@xxxxxxxxxxxxxx>
> >
> > Now, addresses of memory cgroup can be calculated by their ID without complex.
> > This patch relplaces pc->mem_cgroup from a pointer to a unsigned short.
> > On 64bit architecture, this offers us more 6bytes room per page_cgroup.
> > Use 2bytes for blkio-cgroup's page tracking. More 4bytes will be used for
> > some light-weight concurrent access.
> >
> > We may able to move this id onto flags field but ...go step by step.
> >
> > Signed-off-by: KAMEZAWA Hiroyuki <kamezawa.hiroyu@xxxxxxxxxxxxxx>
> > ---
> > include/linux/page_cgroup.h | 3 ++-
> > mm/memcontrol.c | 40 +++++++++++++++++++++++++---------------
> > mm/page_cgroup.c | 2 +-
> > 3 files changed, 28 insertions(+), 17 deletions(-)
> >
> > Index: mmotm-0719/include/linux/page_cgroup.h
> > ===================================================================
> > --- mmotm-0719.orig/include/linux/page_cgroup.h
> > +++ mmotm-0719/include/linux/page_cgroup.h
> > @@ -12,7 +12,8 @@
> > */
> > struct page_cgroup {
> > unsigned long flags;
> > - struct mem_cgroup *mem_cgroup;
> > + unsigned short mem_cgroup; /* ID of assigned memory cgroup */
> > + unsigned short blk_cgroup; /* Not Used..but will be. */
>
> So later I shall have to use virtually indexed arrays in blkio controller?
> Or you are just using virtually indexed arrays for lookup speed and
> I can continue to use css_lookup() and not worry about using virtually
> indexed arrays.
>
yes. you can use css_lookup() even if it's slow.
> So the idea is that when a page is allocated, also store the blk_group
> id and once that page is submitted for writeback, we should be able
> to associate it to right blkio group?
>
blk_cgroup id can be attached whenever you wants. please overwrite
page_cgroup->blk_cgroup when it's necessary.
Did you read Ikeda's patch ? I myself doesn't have patches at this point.
This is just for make a room for recording blkio-ID, which was requested
for a year.
Hmm, but page-allocation-time doesn't sound very good for me.
Thanks.
-Kame
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