Messages in this thread | | | Date | Mon, 17 Mar 2008 10:02:09 +0800 | From | "Paul Menage" <> | Subject | Re: [RFC][2/3] Account and control virtual address space allocations |
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On Mon, Mar 17, 2008 at 1:30 AM, Balbir Singh <balbir@linux.vnet.ibm.com> wrote: > /* > + * Check if the current cgroup exceeds its address space limit. > + * Returns 0 on success and 1 on failure. > + */ > +int mem_cgroup_update_as(struct mm_struct *mm, long nr_pages) > +{ > + int ret = 0; > + struct mem_cgroup *mem; > + if (mem_cgroup_subsys.disabled) > + return ret; > + > + rcu_read_lock(); > + mem = rcu_dereference(mm->mem_cgroup); > + css_get(&mem->css); > + rcu_read_unlock(); > +
How about if this function avoided charging the root cgroup? You'd save 4 atomic operations on a global data structure on every mmap/munmap when the virtual address limit cgroup wasn't in use, which could be significant on a large system. And I don't see situations where you really need to limit the address space of the root cgroup.
Paul
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