Glauber Costa Messages: 916 Registered: October 2011
Senior Member
On 08/10/2012 09:27 PM, Kamezawa Hiroyuki wrote:
>> +bool __memcg_kmem_new_page(gfp_t gfp, void *_handle, int order)
>> > +{
>> > + struct mem_cgroup *memcg;
>> > + struct mem_cgroup **handle = (struct mem_cgroup **)_handle;
>> > + bool ret = true;
>> > + size_t size;
>> > + struct task_struct *p;
>> > +
>> > + *handle = NULL;
>> > + rcu_read_lock();
>> > + p = rcu_dereference(current->mm->owner);
>> > + memcg = mem_cgroup_from_task(p);
>> > + if (!memcg_kmem_enabled(memcg))
>> > + goto out;
>> > +
>> > + mem_cgroup_get(memcg);
>> > +
> This mem_cgroup_get() will be a potentioal performance problem.
> Don't you have good idea to avoid accessing atomic counter here ?
> I think some kind of percpu counter or a feature to disable "move task"
> will be a help.
>
>
I have just sent out a proposal to deal with this. I tried the trick of
marking only the first charge and last uncharge, and it works quite
alright at the cost of a bit test on most calls to memcg_kmem_charge.
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