RE: [RFC][PATCH 0/1]a new optional function for task assignment to cgroup

["Kazunaga Ikeno" <k-ikeno@ak.jp.nec.com>]

Paul Menage wrote:
> This is something that's been discussed before, originally as part of
> CKRM with a complex rule engine in the kernel space.
> 
> Basically, the general agreement was that it's a case where a simple
> API is going to be too simple for the majority of users, and a complex
> API that satisfies everyone is going to be too messy/heavyweight.
> 
> This is something that can be done in a userspace daemon via the
> process events connector - when you get a PROC_EVENT_UID event, you
> can move the process into the appropriate cgroup (you may also need to
> check any recently-forked children). This also gives you more
> flexibility than you can have in the kernel - you can base your
> decision on more complex factors than simply the uid of the process.
> 
> Dhaval Giani had a prototype implementation of such a daemon.

Paul - 

Thank you for your comment.
Because it was the almost same timing, I did not notice about Dhaval Giani's plan. 
I will investigate it.

- Kazunaga Ikeno.

> 
> Paul
> 
> >
> >  == Description =============================================
> >
> >  This patch provides the function that leads a task, corresponding to the conditions
> >  specified beforehand, to a specific cgroup directory.
> >
> >  Currently, this patch uses user-id as a condition to lead a task. On its I/F,
> >  specifies user-id of a task and a cgroup directory.
> >
> >  The task set to specified user-id will automatically lead to the cgroup directory.
> >  (it is attached to specific cgroup)
> >
> >  This function makes possible to attach a task to cgroup automatically when
> >  specific user logs in, also to attach a task of a service which is set to
> >  specific effective user-id to specific cgroup mechanically.
> >
> >  This function is just option, all the functions of cgroup are the same.
> >  Also the migration of a task between cgroup directories can do by rewriting pid
> >  of a control tasks file, including a task leading by this option.
> >
> >  It is able to enter two or more set of user-id and cgroup directory.
> >  Specified cgroup directory may be the same or that may not be.
> >  But it's not able to enter same user-id to plural cgroup directories to lead.
> >
> >
> >  == Interface ===============================================
> >
> >    /lead_option  -  control file of this option
> >
> >  [example for reading a configuration]
> >
> >        # cat /cgroup/lead_option
> >
> >        uid:202        leadto:/cpuset/bar_cg
> >        uid:201        leadto:/cpuset/foo_cg
> >
> >       * nothing appears before assignment.
> >
> >  [example for adding an entry]
> >  - To lead a task(uid 201) to /cgroup/foo_cg
> >
> >        # echo uid:201 leadto:/cpuset/foo_cg > /cpuset/lead_option
> >
> >        * set a uid of task and cgroup dirctory to lead.
> >        * Remake an entry uid to cgroup directory if set uid already exists.
> >
> >  [example for delete an entry]
> >  - To delete an entry of uid
> >
> >        # echo uid:201 > /cpuset/lead_option
> >
> >        * To delete a registration, omit "leadto:" token.
> >
> >
> >  == Operation example (chronological order) ==================
> >
> >  The follows is an example of the operation.
> >
> >  # ############################
> >  # # Various confirmation before testing
> >  # ############################
> >  # id
> >  uid=0(root) gid=0(root) groups=0(root)
> >  # df /cpuset
> >  Filesystem           1K-blocks      Used Available Use% Mounted on
> >  none                         0         0         0   -  /cpuset
> >  # more /proc/self/cgroup
> >  cpuset:/
> >  # id foo
> >  uid=201(foo) gid=100(users) groups=100(users)
> >  # id bar
> >  uid=202(foo) gid=100(users) groups=100(users)
> >  # ############################
> >  # # Add an entry of user foo,bar
> >  # ############################
> >  # echo uid:201 leadto:/cpuset/foo_cg > /cpuset/lead_option
> >  # echo uid:202 leadto:/cpuset/bar_cg > /cpuset/lead_option
> >  # more /cpuset/lead_option
> >  uid:202        leadto:/cpuset/bar_cg
> >  uid:201        leadto:/cpuset/foo_cg
> >  # ############################
> >  # # Confirmation of the assignment of user foo,bar - (1)
> >  # ############################
> >  # su - foo
> >  $ more /proc/$$/cgroup
> >  cpuset:/foo_cg
> >  $ more /proc/self/cgroup
> >  cpuset:/foo_cg
> >  $ su bar --command "more /proc/self/cgroup"
> >  cpuset:/bar_cg
> >  $ exit
> >  # ############################
> >  # # Delete an entry of user foo,bar
> >  # ############################
> >  # echo uid:201 > /cpuset/lead_option
> >  # echo uid:202 > /cpuset/lead_option
> >  # more /cpuset/lead_option
> >  # ############################
> >  # # Confirmation of the assignment of user foo,bar - (2)
> >  # ############################
> >  # su - foo
> >  $ more /proc/$$/cgroup
> >  cpuset:/
> >  $ su bar --command "more /proc/self/cgroup"
> >  cpuset:/
> >  $
> >
> >
> >  Thanks,
> >  - Kazunaga Ikeno.
> >
> >
> >
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