Re: [PATCH v3] fork: free vmapped stacks in cache when cpus are offline

From	Thomas Gleixner <tglx@linutronix.de>
Newsgroups	linux.kernel
Subject	Re: [PATCH v3] fork: free vmapped stacks in cache when cpus are offline
Date	2017-02-10 16:40 +0100
Message-ID	<t9lsK-5dQ-19@gated-at.bofh.it> (permalink)
References	<t9eUi-105-17@gated-at.bofh.it> <t9ibx-3dS-27@gated-at.bofh.it> <t9kwG-4AQ-23@gated-at.bofh.it> <t9kGm-4F0-3@gated-at.bofh.it> <t9kZI-52n-25@gated-at.bofh.it>
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On Sat, 11 Feb 2017, Hoeun Ryu wrote:

> On Fri, Feb 10, 2017 at 11:41 PM, Michal Hocko <mhocko@kernel.org> wrote:
> > On Fri 10-02-17 23:31:41, Hoeun Ryu wrote:
> >> On Fri, Feb 10, 2017 at 9:05 PM, Michal Hocko <mhocko@kernel.org> wrote:
> >> > On Fri 10-02-17 17:32:07, Hoeun Ryu wrote:
> > [...]
> >> >>  static unsigned long *alloc_thread_stack_node(struct task_struct *tsk, int node)
> >> >> @@ -456,6 +474,11 @@ void __init fork_init(void)
> >> >>       for (i = 0; i < UCOUNT_COUNTS; i++) {
> >> >>               init_user_ns.ucount_max[i] = max_threads/2;
> >> >>       }
> >> >> +
> >> >> +#ifdef CONFIG_VMAP_STACK
> >> >> +     cpuhp_setup_state(CPUHP_AP_ONLINE_DYN, "vm_stack_cache",
> >> >> +                       NULL, free_vm_stack_cache);
> >> >> +#endif
> >> >
> >> > I am not familiar the new hotplug infrastructure so I might be missing
> >> > something. CPUHP_AP_ONLINE_DYN will allocate a state which is has only
> >> > 30 slots available.

That's enough and when we hit that limit we just up it.

> >> > The name also suggests this will be called on an online event.

The states are symmetric.

Thread

[PATCH v3] fork: free vmapped stacks in cache when cpus are offline Hoeun Ryu <hoeun.ryu@gmail.com> - 2017-02-10 09:40 +0100
  Re: [PATCH v3] fork: free vmapped stacks in cache when cpus are  offline Michal Hocko <mhocko@kernel.org> - 2017-02-10 13:10 +0100
    Re: [PATCH v3] fork: free vmapped stacks in cache when cpus are offline Hoeun Ryu <hoeun.ryu@gmail.com> - 2017-02-10 15:40 +0100
      Re: [PATCH v3] fork: free vmapped stacks in cache when cpus are  offline Michal Hocko <mhocko@kernel.org> - 2017-02-10 15:50 +0100
        Re: [PATCH v3] fork: free vmapped stacks in cache when cpus are offline Hoeun Ryu <hoeun.ryu@gmail.com> - 2017-02-10 16:10 +0100
          Re: [PATCH v3] fork: free vmapped stacks in cache when cpus are  offline Thomas Gleixner <tglx@linutronix.de> - 2017-02-10 16:40 +0100
        Re: [PATCH v3] fork: free vmapped stacks in cache when cpus are  offline Thomas Gleixner <tglx@linutronix.de> - 2017-02-10 16:40 +0100
          Re: [PATCH v3] fork: free vmapped stacks in cache when cpus are offline Hoeun Ryu <hoeun.ryu@gmail.com> - 2017-02-10 18:00 +0100
            Re: [PATCH v3] fork: free vmapped stacks in cache when cpus are  offline Thomas Gleixner <tglx@linutronix.de> - 2017-02-10 19:00 +0100
              Re: [PATCH v3] fork: free vmapped stacks in cache when cpus are offline Hoeun Ryu <hoeun.ryu@gmail.com> - 2017-02-11 00:40 +0100

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