On Tue, 24 Aug 2010 00:19:01 -0700
Greg Thelen <gthelen@xxxxxxxxxx> wrote:
> KAMEZAWA Hiroyuki <kamezawa.hiroyu@xxxxxxxxxxxxxx> writes:
>
> > CC'ed to Paul Menage and Li Zefan.
> > ==
> > From: KAMEZAWA Hiroyuki <kamezawa.hiroyu@xxxxxxxxxxxxxx>
> >
> > When cgroup subsystem use ID (ss->use_id==1), each css's ID is assigned
> > after successful call of ->create(). css_ID is tightly coupled with
> > css struct itself but it is allocated by ->create() call, IOW,
> > per-subsystem special allocations.
> >
> > To know css_id before creation, this patch adds id_attached() callback.
> > after css_ID allocation. This will be used by memory cgroup's quick lookup
> > routine.
> >
> > Maybe you can think of other implementations as
> > - pass ID to ->create()
> > or
> > - add post_create()
> > etc...
> > But when considering dirtiness of codes, this straightforward patch seems
> > good to me. If someone wants post_create(), this patch can be replaced.
> >
> > Changelog: 20100820
> > - new approarch.
> >
> > Signed-off-by: KAMEZAWA Hiroyuki <kamezawa.hiroyu@xxxxxxxxxxxxxx>
> > ---
> > Documentation/cgroups/cgroups.txt | 10 ++++++++++
> > include/linux/cgroup.h | 1 +
> > kernel/cgroup.c | 5 ++++-
> > 3 files changed, 15 insertions(+), 1 deletion(-)
> >
> > Index: mmotm-0811/Documentation/cgroups/cgroups.txt
> > ===================================================================
> > --- mmotm-0811.orig/Documentation/cgroups/cgroups.txt
> > +++ mmotm-0811/Documentation/cgroups/cgroups.txt
> > @@ -621,6 +621,16 @@ and root cgroup. Currently this will onl
> > the default hierarchy (which never has sub-cgroups) and a hierarchy
> > that is being created/destroyed (and hence has no sub-cgroups).
> >
> > +void id_attached(struct cgroup_subsys *ss, struct cgroup *root)
> > +(cgroup_mutex and ss->hierarchy_mutex held by caller)
> > +(called only when ss->use_id=1)
> > +
> > +Called when css_id is attached to css. Because css_id is assigned
> > +against "css", css_id is not available until ->create() is called.
> > +If subsystem wants to make use of ID at createtion time, use
>
> Minor spelling correction: s/createtion/creation/
>
ok.
> > +this handler. This handler will be called after css_id is assigned
> > +to css. Not necessary to be implemented in usual(see memcontrol.c)
>
> Maybe this sounds better?
>
> "This handler is not usually needed. See memcontrol.c for an example."
>
Sure. will fix.
> > +
> > 4. Questions
> > ============
> >
> > Index: mmotm-0811/include/linux/cgroup.h
> > ===================================================================
> > --- mmotm-0811.orig/include/linux/cgroup.h
> > +++ mmotm-0811/include/linux/cgroup.h
> > @@ -475,6 +475,7 @@ struct cgroup_subsys {
> > struct cgroup *cgrp);
> > void (*post_clone)(struct cgroup_subsys *ss, struct cgroup *cgrp);
> > void (*bind)(struct cgroup_subsys *ss, struct cgroup *root);
> > + void (*id_attached)(struct cgroup_subsys *ss, struct cgroup *cgrp);
> >
> > int subsys_id;
> > int active;
> > Index: mmotm-0811/kernel/cgroup.c
> > ===================================================================
> > --- mmotm-0811.orig/kernel/cgroup.c
> > +++ mmotm-0811/kernel/cgroup.c
> > @@ -4618,6 +4618,8 @@ static int __init_or_module cgroup_init_
> > newid->stack[0] = newid->id;
> > newid->css = rootcss;
> > rootcss->id = newid;
> > + if (ss->id_attached)
> > + ss->id_attached(ss, dummytop);
> > return 0;
> > }
> >
> > @@ -4646,7 +4648,8 @@ static int alloc_css_id(struct cgroup_su
> > * see cgroup_populate_dir()
> > */
> > rcu_assign_pointer(child_css->id, child_id);
> > -
> > + if (ss->id_attached)
> > + ss->id_attached(ss, child);
> > return 0;
> > }
> >
>
Thank you for review.
-Kame
--
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>