Messages in this thread | | | Date | Mon, 17 Mar 2008 18:21:41 +0530 | From | Balbir Singh <> | Subject | Re: [RFC][2/3] Account and control virtual address space allocations |
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Pavel Emelyanov wrote: > Balbir Singh wrote: >> Pavel Emelyanov wrote: >>> [snip] >>> >>>> +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(); >>>> + >>>> + if (nr_pages > 0) { >>>> + if (res_counter_charge(&mem->as_res, (nr_pages * PAGE_SIZE))) >>>> + ret = 1; >>>> + } else >>>> + res_counter_uncharge(&mem->as_res, (-nr_pages * PAGE_SIZE)); >>> No, please, no. Let's make two calls - mem_cgroup_charge_as and mem_cgroup_uncharge_as. >>> >>> [snip] >>> >> Yes, sure :) > > Thanks :) > >>>> @@ -1117,6 +1117,9 @@ munmap_back: >>>> } >>>> } >>>> >>>> + if (mem_cgroup_update_as(mm, len >> PAGE_SHIFT)) >>>> + return -ENOMEM; >>>> + >>> Why not use existintg cap_vm_enough_memory and co? >>> >> I thought about it and almost used may_expand_vm(), but there is a slight catch >> there. With cap_vm_enough_memory() or security_vm_enough_memory(), they are >> called after total_vm has been calculated. In our case we need to keep the >> cgroups equivalent of total_vm up to date, and we do this in mem_cgorup_update_as. > > So? What prevents us from using these hooks? :)
1. We need to account total_vm usage of the task anyway. So why have two places, one for accounting and second for control? 2. These hooks are activated for conditionally invoked for vma's with VM_ACCOUNT set.
-- Warm Regards, Balbir Singh Linux Technology Center IBM, ISTL
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