lkml.org 
[lkml]   [2008]   [Apr]   [4]   [last100]   RSS Feed
Views: [wrap][no wrap]   [headers]  [forward] 
 
Messages in this thread
/
Date
From
SubjectRe: [-mm] Add an owner to the mm_struct (v8)
Paul Menage wrote:
> On Fri, Apr 4, 2008 at 1:05 AM, Balbir Singh <balbir@linux.vnet.ibm.com> wrote:
>> After the thread group leader exits, it's moved to init_css_state by
>> cgroup_exit(), thus all future charges from runnings threads would
>> be redirected to the init_css_set's subsystem.
>
> And its uncharges, which is more of the problem I was getting at
> earlier - surely when the mm is finally destroyed, all its virtual
> address space charges will be uncharged from the root cgroup rather
> than the correct cgroup, if we left the delayed group leader as the
> owner? Which is why I think the group leader optimization is unsafe.

It won't uncharge for the memory controller from the root cgroup since each page
has the mem_cgroup information associated with it. For other controllers,
they'll need to monitor exit() callbacks to know when the leader is dead :( (sigh).

Not having the group leader optimization can introduce big overheads (consider
thousands of tasks, with the group leader being the first one to exit).

--
Warm Regards,
Balbir Singh
Linux Technology Center
IBM, ISTL


\
 
 \ /
  Last update: 2008-04-04 10:31    [W:0.448 / U:0.016 seconds]
©2003-2020 Jasper Spaans|hosted at Digital Ocean and TransIP|Read the blog|Advertise on this site