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From: Vivek Goyal on 27 Jul 2010 22:40 On Tue, Jul 27, 2010 at 04:54:17PM +0900, KAMEZAWA Hiroyuki wrote: > From: KAMEZAWA Hiroyuki <kamezawa.hiroyu(a)jp.fujitsu.com> > > When a subsystem want to make use of "id" more, it's necessary to > manage the id at cgroup subsystem creation time. But, now, > because of the order of cgroup creation callback, subsystem can't > declare the id it wants. This patch allows subsystem to use customized > ID for themselves. > > Signed-off-by: KAMEZAWA Hiroyuki <kamezawa.hiroyu(a)jp.fujitsu.com> [..] > Index: mmotm-2.6.35-0719/Documentation/cgroups/cgroups.txt > =================================================================== > --- mmotm-2.6.35-0719.orig/Documentation/cgroups/cgroups.txt > +++ mmotm-2.6.35-0719/Documentation/cgroups/cgroups.txt > @@ -621,6 +621,15 @@ 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 custom_id(struct cgroup_subsys *ss, struct cgroup *cgrp) > + > +Called at assigning a new ID to cgroup subsystem state struct. This > +is called when ss->use_id == true. If this function is not provided, > +a new ID is automatically assigned. If you enable ss->use_id, > +you can use css_lookup() and css_get_next() to access "css" objects > +via IDs. > + Couple of lines to explain why a subsystem would like to assign its own ids and not be happy with generic cgroup assigned id be helpful. In this case, I think you are using this id as index into array and want to control the index, hence you seem to be doing it. But I am not sure again why do you want to control index? Vivek -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo(a)vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
From: KAMEZAWA Hiroyuki on 27 Jul 2010 22:50 On Tue, 27 Jul 2010 22:30:27 -0400 Vivek Goyal <vgoyal(a)redhat.com> wrote: > > Index: mmotm-2.6.35-0719/Documentation/cgroups/cgroups.txt > > =================================================================== > > --- mmotm-2.6.35-0719.orig/Documentation/cgroups/cgroups.txt > > +++ mmotm-2.6.35-0719/Documentation/cgroups/cgroups.txt > > @@ -621,6 +621,15 @@ 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 custom_id(struct cgroup_subsys *ss, struct cgroup *cgrp) > > + > > +Called at assigning a new ID to cgroup subsystem state struct. This > > +is called when ss->use_id == true. If this function is not provided, > > +a new ID is automatically assigned. If you enable ss->use_id, > > +you can use css_lookup() and css_get_next() to access "css" objects > > +via IDs. > > + > > Couple of lines to explain why a subsystem would like to assign its > own ids and not be happy with generic cgroup assigned id be helpful. > In this case, I think you are using this id as index into array > and want to control the index, hence you seem to be doing it. > > But I am not sure again why do you want to control index? > Now, the subsystem allocation/id-allocation order is ->create() alloc_id. Otherwise "id" of memory cgroup is just determined by the place in virtual-indexed array. As memcg = mem_cgroup_base + id This "id" is determined at create(). If "id" is determined regardless of memory cgroup's placement, it's of no use. My original design of css_id() allocates id in create() but it was moved to generic part. So, this is expected change in my plan. We have 2 choices. id = alloc_id() create(id) or this patch. Both are okay for me. But alloc id before create() may add some ugly rollback. Thanks, -Kame -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo(a)vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
From: Vivek Goyal on 27 Jul 2010 23:20 On Wed, Jul 28, 2010 at 11:35:29AM +0900, KAMEZAWA Hiroyuki wrote: > On Tue, 27 Jul 2010 22:30:27 -0400 > Vivek Goyal <vgoyal(a)redhat.com> wrote: > > > > Index: mmotm-2.6.35-0719/Documentation/cgroups/cgroups.txt > > > =================================================================== > > > --- mmotm-2.6.35-0719.orig/Documentation/cgroups/cgroups.txt > > > +++ mmotm-2.6.35-0719/Documentation/cgroups/cgroups.txt > > > @@ -621,6 +621,15 @@ 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 custom_id(struct cgroup_subsys *ss, struct cgroup *cgrp) > > > + > > > +Called at assigning a new ID to cgroup subsystem state struct. This > > > +is called when ss->use_id == true. If this function is not provided, > > > +a new ID is automatically assigned. If you enable ss->use_id, > > > +you can use css_lookup() and css_get_next() to access "css" objects > > > +via IDs. > > > + > > > > Couple of lines to explain why a subsystem would like to assign its > > own ids and not be happy with generic cgroup assigned id be helpful. > > In this case, I think you are using this id as index into array > > and want to control the index, hence you seem to be doing it. > > > > But I am not sure again why do you want to control index? > > > > Now, the subsystem allocation/id-allocation order is > > ->create() > alloc_id. > > Otherwise "id" of memory cgroup is just determined by the place in virtual-indexed > array. > As > memcg = mem_cgroup_base + id > > This "id" is determined at create(). > > If "id" is determined regardless of memory cgroup's placement, it's of no use. > My original design of css_id() allocates id in create() but it was moved to > generic part. So, this is expected change in my plan. > > We have 2 choices. > id = alloc_id() > create(id) > or > this patch. > > Both are okay for me. But alloc id before create() may add some ugly rollback. Ok, so in current design at the time of mem_cgroup instantiation css_id is not available so you don't know at what index to put the newly instantiated mem_cgroup object, hence the notion of let subsys decide the css_id and cgroup can query from subsystem later. I don't have any preference. Anything simple works.. Vivek -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo(a)vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
From: Balbir Singh on 2 Aug 2010 14:10 * KAMEZAWA Hiroyuki <kamezawa.hiroyu(a)jp.fujitsu.com> [2010-07-27 16:54:17]: > From: KAMEZAWA Hiroyuki <kamezawa.hiroyu(a)jp.fujitsu.com> > > When a subsystem want to make use of "id" more, it's necessary to > manage the id at cgroup subsystem creation time. But, now, > because of the order of cgroup creation callback, subsystem can't > declare the id it wants. This patch allows subsystem to use customized > ID for themselves. > > Signed-off-by: KAMEZAWA Hiroyuki <kamezawa.hiroyu(a)jp.fujitsu.com> > --- What happens if the id is taken already? Could you please explain how this is used? -- Three Cheers, Balbir -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo(a)vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
From: KAMEZAWA Hiroyuki on 2 Aug 2010 20:00
On Mon, 2 Aug 2010 23:34:29 +0530 Balbir Singh <balbir(a)linux.vnet.ibm.com> wrote: > * KAMEZAWA Hiroyuki <kamezawa.hiroyu(a)jp.fujitsu.com> [2010-07-27 16:54:17]: > > > From: KAMEZAWA Hiroyuki <kamezawa.hiroyu(a)jp.fujitsu.com> > > > > When a subsystem want to make use of "id" more, it's necessary to > > manage the id at cgroup subsystem creation time. But, now, > > because of the order of cgroup creation callback, subsystem can't > > declare the id it wants. This patch allows subsystem to use customized > > ID for themselves. > > > > Signed-off-by: KAMEZAWA Hiroyuki <kamezawa.hiroyu(a)jp.fujitsu.com> > > --- > > What happens if the id is taken already? Could you please explain how > this is used? > This patch is dropped. -Kame -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo(a)vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/ |