On Thu, Jul 2, 2020 at 4:18 PM Peter Zijlstra <pet...@infradead.org> wrote: > > On Thu, Jul 02, 2020 at 01:20:43PM +0800, Weiping Zhang wrote: > > Since setid will create a autogroup for that process, there is no > > way to detach a process from that autogroup, this patch add a new interface > > to detach a process from its autogroup. You can write anything to > > /proc/<pid>/autogroup_detach to do that. > > This is indeed what the patch does; but it fails to tell me why. Why do > we want this? Why should I care about your patch :-) > > Please, always explain why you want things done, that can also help us > consider if the proposed solution is the right one.
The reason is that, there are lots of autogroup created in our system, because I forgot to disable CONFIG_SCHED_AUTOGROUP, and it leads to a hotspot in tg_load_down (kenrel-3.10.0-514.16.1.el7.x86_64). When user login system by ssh and launch a background job, it will create a new autogroup even user logout ssh. I cannot find a way do clear these unused autogroup by current kernel, so I write a separate module to clear those unused autogroup for my system. I think we should provide a interface to detach a process's autogroup. Thanks
