From b851ee7921fabdd7dfc96ffc4e9609f5062bd12b Mon Sep 17 00:00:00 2001 From: Li Zefan Date: Wed, 18 Feb 2009 14:48:14 -0800 Subject: cgroups: update documentation about css_set hash table The css_set hash table was introduced in 2.6.26, so update the documentation accordingly. Signed-off-by: Li Zefan Acked-by: Paul Menage Signed-off-by: Andrew Morton Signed-off-by: Linus Torvalds --- Documentation/cgroups/cgroups.txt | 6 ++---- 1 file changed, 2 insertions(+), 4 deletions(-) (limited to 'Documentation/cgroups/cgroups.txt') diff --git a/Documentation/cgroups/cgroups.txt b/Documentation/cgroups/cgroups.txt index d9e5d6f41b92..93feb8444489 100644 --- a/Documentation/cgroups/cgroups.txt +++ b/Documentation/cgroups/cgroups.txt @@ -252,10 +252,8 @@ cgroup file system directories. When a task is moved from one cgroup to another, it gets a new css_set pointer - if there's an already existing css_set with the desired collection of cgroups then that group is reused, else a new -css_set is allocated. Note that the current implementation uses a -linear search to locate an appropriate existing css_set, so isn't -very efficient. A future version will use a hash table for better -performance. +css_set is allocated. The appropriate existing css_set is located by +looking into a hash table. To allow access from a cgroup to the css_sets (and hence tasks) that comprise it, a set of cg_cgroup_link objects form a lattice; -- cgit v1.2.2 From caa790ba6cb88dccfab356960d93e2f4e0bd8704 Mon Sep 17 00:00:00 2001 From: Chris Samuel Date: Sat, 17 Jan 2009 00:01:18 +1100 Subject: trivial: cgroups: documentation typo and spelling corrections Minor typo and spelling corrections fixed whilst reading to learn about cgroups capabilities. Signed-off-by: Chris Samuel Acked-by: Paul Menage Signed-off-by: Jiri Kosina --- Documentation/cgroups/cgroups.txt | 10 +++++----- 1 file changed, 5 insertions(+), 5 deletions(-) (limited to 'Documentation/cgroups/cgroups.txt') diff --git a/Documentation/cgroups/cgroups.txt b/Documentation/cgroups/cgroups.txt index 93feb8444489..f4f5ee97d4db 100644 --- a/Documentation/cgroups/cgroups.txt +++ b/Documentation/cgroups/cgroups.txt @@ -56,7 +56,7 @@ hierarchy, and a set of subsystems; each subsystem has system-specific state attached to each cgroup in the hierarchy. Each hierarchy has an instance of the cgroup virtual filesystem associated with it. -At any one time there may be multiple active hierachies of task +At any one time there may be multiple active hierarchies of task cgroups. Each hierarchy is a partition of all tasks in the system. User level code may create and destroy cgroups by name in an @@ -124,10 +124,10 @@ following lines: / \ Prof (15%) students (5%) -Browsers like firefox/lynx go into the WWW network class, while (k)nfsd go +Browsers like Firefox/Lynx go into the WWW network class, while (k)nfsd go into NFS network class. -At the same time firefox/lynx will share an appropriate CPU/Memory class +At the same time Firefox/Lynx will share an appropriate CPU/Memory class depending on who launched it (prof/student). With the ability to classify tasks differently for different resources @@ -325,7 +325,7 @@ and then start a subshell 'sh' in that cgroup: Creating, modifying, using the cgroups can be done through the cgroup virtual filesystem. -To mount a cgroup hierarchy will all available subsystems, type: +To mount a cgroup hierarchy with all available subsystems, type: # mount -t cgroup xxx /dev/cgroup The "xxx" is not interpreted by the cgroup code, but will appear in @@ -521,7 +521,7 @@ always handled well. void post_clone(struct cgroup_subsys *ss, struct cgroup *cgrp) (cgroup_mutex held by caller) -Called at the end of cgroup_clone() to do any paramater +Called at the end of cgroup_clone() to do any parameter initialization which might be required before a task could attach. For example in cpusets, no task may attach before 'cpus' and 'mems' are set up. -- cgit v1.2.2 From ec64f51545fffbc4cb968f0cea56341a4b07e85a Mon Sep 17 00:00:00 2001 From: KAMEZAWA Hiroyuki Date: Thu, 2 Apr 2009 16:57:26 -0700 Subject: cgroup: fix frequent -EBUSY at rmdir In following situation, with memory subsystem, /groupA use_hierarchy==1 /01 some tasks /02 some tasks /03 some tasks /04 empty When tasks under 01/02/03 hit limit on /groupA, hierarchical reclaim is triggered and the kernel walks tree under groupA. In this case, rmdir /groupA/04 fails with -EBUSY frequently because of temporal refcnt from the kernel. In general. cgroup can be rmdir'd if there are no children groups and no tasks. Frequent fails of rmdir() is not useful to users. (And the reason for -EBUSY is unknown to users.....in most cases) This patch tries to modify above behavior, by - retries if css_refcnt is got by someone. - add "return value" to pre_destroy() and allows subsystem to say "we're really busy!" Signed-off-by: KAMEZAWA Hiroyuki Cc: Paul Menage Cc: Li Zefan Cc: Balbir Singh Cc: Daisuke Nishimura Signed-off-by: Andrew Morton Signed-off-by: Linus Torvalds --- Documentation/cgroups/cgroups.txt | 6 ++++-- 1 file changed, 4 insertions(+), 2 deletions(-) (limited to 'Documentation/cgroups/cgroups.txt') diff --git a/Documentation/cgroups/cgroups.txt b/Documentation/cgroups/cgroups.txt index 93feb8444489..cdc46a501b85 100644 --- a/Documentation/cgroups/cgroups.txt +++ b/Documentation/cgroups/cgroups.txt @@ -476,11 +476,13 @@ cgroup->parent is still valid. (Note - can also be called for a newly-created cgroup if an error occurs after this subsystem's create() method has been called for the new cgroup). -void pre_destroy(struct cgroup_subsys *ss, struct cgroup *cgrp); +int pre_destroy(struct cgroup_subsys *ss, struct cgroup *cgrp); Called before checking the reference count on each subsystem. This may be useful for subsystems which have some extra references even if -there are not tasks in the cgroup. +there are not tasks in the cgroup. If pre_destroy() returns error code, +rmdir() will fail with it. From this behavior, pre_destroy() can be +called multiple times against a cgroup. int can_attach(struct cgroup_subsys *ss, struct cgroup *cgrp, struct task_struct *task) -- cgit v1.2.2 From b6719ec1ad54e47e40633b19703f2c1254708842 Mon Sep 17 00:00:00 2001 From: Li Zefan Date: Thu, 2 Apr 2009 16:57:28 -0700 Subject: cgroups: more documentation for remount and release_agent This won't remove cpuacct from the mounted hierachy: # mount -t cgroup -o cpu,cpuacct xxx /mnt # mount -o remount,cpu /mnt Because for this usage mount(8) will append the new options to the original options. And this will get you right: # mount [-t cgroup] -o remount,cpu xxx /mnt Also document how to specify or change release_agent. Signed-off-by: Li Zefan Reviewd-by: KAMEZAWA Hiroyuki Cc: Paul Menage Signed-off-by: Andrew Morton Signed-off-by: Linus Torvalds --- Documentation/cgroups/cgroups.txt | 20 ++++++++++++++++++-- 1 file changed, 18 insertions(+), 2 deletions(-) (limited to 'Documentation/cgroups/cgroups.txt') diff --git a/Documentation/cgroups/cgroups.txt b/Documentation/cgroups/cgroups.txt index cdc46a501b85..4ea852345a47 100644 --- a/Documentation/cgroups/cgroups.txt +++ b/Documentation/cgroups/cgroups.txt @@ -333,12 +333,23 @@ The "xxx" is not interpreted by the cgroup code, but will appear in To mount a cgroup hierarchy with just the cpuset and numtasks subsystems, type: -# mount -t cgroup -o cpuset,numtasks hier1 /dev/cgroup +# mount -t cgroup -o cpuset,memory hier1 /dev/cgroup To change the set of subsystems bound to a mounted hierarchy, just remount with different options: +# mount -o remount,cpuset,ns hier1 /dev/cgroup -# mount -o remount,cpuset,ns /dev/cgroup +Now memory is removed from the hierarchy and ns is added. + +Note this will add ns to the hierarchy but won't remove memory or +cpuset, because the new options are appended to the old ones: +# mount -o remount,ns /dev/cgroup + +To Specify a hierarchy's release_agent: +# mount -t cgroup -o cpuset,release_agent="/sbin/cpuset_release_agent" \ + xxx /dev/cgroup + +Note that specifying 'release_agent' more than once will return failure. Note that changing the set of subsystems is currently only supported when the hierarchy consists of a single (root) cgroup. Supporting @@ -349,6 +360,11 @@ Then under /dev/cgroup you can find a tree that corresponds to the tree of the cgroups in the system. For instance, /dev/cgroup is the cgroup that holds the whole system. +If you want to change the value of release_agent: +# echo "/sbin/new_release_agent" > /dev/cgroup/release_agent + +It can also be changed via remount. + If you want to create a new cgroup under /dev/cgroup: # cd /dev/cgroup # mkdir my_cgroup -- cgit v1.2.2