Re: [PATCH 9/9 v3] cgroup_freezer: implement proper hierarchy support
On Thu 08-11-12 10:04:17, Tejun Heo wrote: > On Thu, Nov 08, 2012 at 07:02:46PM +0100, Michal Hocko wrote: > > On Thu 08-11-12 09:57:50, Tejun Heo wrote: > > > Signed-off-by: Tejun Heo > > > Reviewed-by: Tejun Heo > > > > You probably meant Reviewed-by: Michal Hocko ;) > > Hehehheheh... man, I'm too self-absolved. Thanks for noticing > that. :) Updated. Heh, btw. the doc update looks good as well. -- Michal Hocko SUSE Labs -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majord...@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
Re: [PATCH 9/9 v3] cgroup_freezer: implement proper hierarchy support
On Thu, Nov 08, 2012 at 07:02:46PM +0100, Michal Hocko wrote: > On Thu 08-11-12 09:57:50, Tejun Heo wrote: > > Signed-off-by: Tejun Heo > > Reviewed-by: Tejun Heo > > You probably meant Reviewed-by: Michal Hocko ;) Hehehheheh... man, I'm too self-absolved. Thanks for noticing that. :) Updated. -- tejun -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majord...@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
Re: [PATCH 9/9 v3] cgroup_freezer: implement proper hierarchy support
On Thu 08-11-12 09:57:50, Tejun Heo wrote: > Up until now, cgroup_freezer didn't implement hierarchy properly. > cgroups could be arranged in hierarchy but it didn't make any > difference in how each cgroup_freezer behaved. They all operated > separately. > > This patch implements proper hierarchy support. If a cgroup is > frozen, all its descendants are frozen. A cgroup is thawed iff it and > all its ancestors are THAWED. freezer.self_freezing shows the current > freezing state for the cgroup itself. freezer.parent_freezing shows > whether the cgroup is freezing because any of its ancestors is > freezing. > > freezer_post_create() locks the parent and new cgroup and inherits the > parent's state and freezer_change_state() applies new state top-down > using cgroup_for_each_descendant_pre() which guarantees that no child > can escape its parent's state. update_if_frozen() uses > cgroup_for_each_descendant_post() to propagate frozen states > bottom-up. > > Synchronization could be coarser and easier by using a single mutex to > protect all hierarchy operations. Finer grained approach was used > because it wasn't too difficult for cgroup_freezer and I think it's > beneficial to have an example implementation and cgroup_freezer is > rather simple and can serve a good one. > > As this makes cgroup_freezer properly hierarchical, > freezer_subsys.broken_hierarchy marking is removed. > > Note that this patch changes userland visible behavior - freezing a > cgroup now freezes all its descendants too. This behavior change is > intended and has been warned via .broken_hierarchy. > > v2: Michal spotted a bug in freezer_change_state() - descendants were > inheriting from the wrong ancestor. Fixed. > > v3: Documentation/cgroups/freezer-subsystem.txt updated. > > Signed-off-by: Tejun Heo > Reviewed-by: Tejun Heo You probably meant Reviewed-by: Michal Hocko ;) -- Michal Hocko SUSE Labs -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majord...@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
Re: [PATCH 9/9 v3] cgroup_freezer: implement proper hierarchy support
On Thu 08-11-12 09:57:50, Tejun Heo wrote: Up until now, cgroup_freezer didn't implement hierarchy properly. cgroups could be arranged in hierarchy but it didn't make any difference in how each cgroup_freezer behaved. They all operated separately. This patch implements proper hierarchy support. If a cgroup is frozen, all its descendants are frozen. A cgroup is thawed iff it and all its ancestors are THAWED. freezer.self_freezing shows the current freezing state for the cgroup itself. freezer.parent_freezing shows whether the cgroup is freezing because any of its ancestors is freezing. freezer_post_create() locks the parent and new cgroup and inherits the parent's state and freezer_change_state() applies new state top-down using cgroup_for_each_descendant_pre() which guarantees that no child can escape its parent's state. update_if_frozen() uses cgroup_for_each_descendant_post() to propagate frozen states bottom-up. Synchronization could be coarser and easier by using a single mutex to protect all hierarchy operations. Finer grained approach was used because it wasn't too difficult for cgroup_freezer and I think it's beneficial to have an example implementation and cgroup_freezer is rather simple and can serve a good one. As this makes cgroup_freezer properly hierarchical, freezer_subsys.broken_hierarchy marking is removed. Note that this patch changes userland visible behavior - freezing a cgroup now freezes all its descendants too. This behavior change is intended and has been warned via .broken_hierarchy. v2: Michal spotted a bug in freezer_change_state() - descendants were inheriting from the wrong ancestor. Fixed. v3: Documentation/cgroups/freezer-subsystem.txt updated. Signed-off-by: Tejun Heo t...@kernel.org Reviewed-by: Tejun Heo t...@kernel.org You probably meant Reviewed-by: Michal Hocko ;) -- Michal Hocko SUSE Labs -- To unsubscribe from this list: send the line unsubscribe linux-kernel in the body of a message to majord...@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
Re: [PATCH 9/9 v3] cgroup_freezer: implement proper hierarchy support
On Thu, Nov 08, 2012 at 07:02:46PM +0100, Michal Hocko wrote: On Thu 08-11-12 09:57:50, Tejun Heo wrote: Signed-off-by: Tejun Heo t...@kernel.org Reviewed-by: Tejun Heo t...@kernel.org You probably meant Reviewed-by: Michal Hocko ;) Hehehheheh... man, I'm too self-absolved. Thanks for noticing that. :) Updated. -- tejun -- To unsubscribe from this list: send the line unsubscribe linux-kernel in the body of a message to majord...@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
Re: [PATCH 9/9 v3] cgroup_freezer: implement proper hierarchy support
On Thu 08-11-12 10:04:17, Tejun Heo wrote: On Thu, Nov 08, 2012 at 07:02:46PM +0100, Michal Hocko wrote: On Thu 08-11-12 09:57:50, Tejun Heo wrote: Signed-off-by: Tejun Heo t...@kernel.org Reviewed-by: Tejun Heo t...@kernel.org You probably meant Reviewed-by: Michal Hocko ;) Hehehheheh... man, I'm too self-absolved. Thanks for noticing that. :) Updated. Heh, btw. the doc update looks good as well. -- Michal Hocko SUSE Labs -- To unsubscribe from this list: send the line unsubscribe linux-kernel in the body of a message to majord...@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
