This patch is sent as an answer to a previous thread around the ns_cgroup. https://lists.linux-foundation.org/pipermail/containers/2009-June/018627.html It adds a control file 'clone_children' for a cgroup. This control file is a boolean specifying if the child cgroup should be a clone of the parent cgroup or not. The default value is 'false'. This flag makes the child cgroup to call the post_clone callback of all the subsystem, if it is available. At present, the cpuset is the only one which had implemented the post_clone callback. Signed-off-by: Daniel Lezcano <daniel.lezcano@xxxxxxx> Cc: Paul Menage <menage@xxxxxxxxxx> Cc: Serge E. Hallyn <serue@xxxxxxxxxx> --- Documentation/cgroups/cgroups.txt | 14 ++++++++++++-- include/linux/cgroup.h | 4 ++++ kernel/cgroup.c | 26 ++++++++++++++++++++++++++ 3 files changed, 42 insertions(+), 2 deletions(-) Index: linux-2.6/include/linux/cgroup.h =================================================================== --- linux-2.6.orig/include/linux/cgroup.h +++ linux-2.6/include/linux/cgroup.h @@ -139,6 +139,10 @@ enum { * A thread in rmdir() is wating for this cgroup. */ CGRP_WAIT_ON_RMDIR, + /* + * Clone cgroup values when creating a new child cgroup + */ + CGRP_CLONE_CHILDREN, }; /* which pidlist file are we talking about? */ Index: linux-2.6/kernel/cgroup.c =================================================================== --- linux-2.6.orig/kernel/cgroup.c +++ linux-2.6/kernel/cgroup.c @@ -2789,6 +2789,23 @@ static int cgroup_write_notify_on_releas return 0; } +static u64 cgroup_clone_children_read(struct cgroup *cgrp, + struct cftype *cft) +{ + return test_bit(CGRP_CLONE_CHILDREN, &cgrp->flags); +} + +static int cgroup_clone_children_write(struct cgroup *cgrp, + struct cftype *cft, + u64 val) +{ + if (val) + set_bit(CGRP_CLONE_CHILDREN, &cgrp->flags); + else + clear_bit(CGRP_CLONE_CHILDREN, &cgrp->flags); + return 0; +} + /* * for the common functions, 'private' gives the type of file */ @@ -2814,6 +2831,11 @@ static struct cftype files[] = { .read_u64 = cgroup_read_notify_on_release, .write_u64 = cgroup_write_notify_on_release, }, + { + .name = "clone_children", + .read_u64 = cgroup_clone_children_read, + .write_u64 = cgroup_clone_children_write, + }, }; static struct cftype cft_release_agent = { @@ -2946,6 +2968,10 @@ static long cgroup_create(struct cgroup if (alloc_css_id(ss, parent, cgrp)) goto err_destroy; /* At error, ->destroy() callback has to free assigned ID. */ + + if (test_bit(CGRP_CLONE_CHILDREN, &parent->flags)) + if (ss->post_clone) + ss->post_clone(ss, cgrp); } cgroup_lock_hierarchy(root); Index: linux-2.6/Documentation/cgroups/cgroups.txt =================================================================== --- linux-2.6.orig/Documentation/cgroups/cgroups.txt +++ linux-2.6/Documentation/cgroups/cgroups.txt @@ -18,7 +18,8 @@ CONTENTS: 1.2 Why are cgroups needed ? 1.3 How are cgroups implemented ? 1.4 What does notify_on_release do ? - 1.5 How do I use cgroups ? + 1.5 What does clone_children do ? + 1.6 How do I use cgroups ? 2. Usage Examples and Syntax 2.1 Basic Usage 2.2 Attaching processes @@ -292,7 +293,16 @@ notify_on_release in the root cgroup at value of their parents notify_on_release setting. The default value of a cgroup hierarchy's release_agent path is empty. -1.5 How do I use cgroups ? +1.5 What does clone_children do ? +--------------------------------- + +If the clone_children flag is enabled (1) in a cgroup, then all +cgroups created beneath will call the post_clone callbacks for each +subsystem of the newly created cgroup. Usually when this callback is +implemented for a subsystem, it copies the values of the parent +subsystem, this is the case for the cpuset. + +1.6 How do I use cgroups ? -------------------------- To start a new job that is to be contained within a cgroup, using _______________________________________________ Containers mailing list Containers@xxxxxxxxxxxxxxxxxxxxxxxxxx https://lists.linux-foundation.org/mailman/listinfo/containers
