| Re: [PATCH v8 1/9] Basic kernel memory functionality for the Memory Controller [message #44468 is a reply to message #44454] |
Fri, 09 December 2011 12:40   |
Glauber Costa
Messages: 916
Registered: October 2011
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Senior Member |
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On 12/08/2011 11:21 PM, KAMEZAWA Hiroyuki wrote:
> On Mon, 5 Dec 2011 19:34:55 -0200
> Glauber Costa<glommer@parallels.com> wrote:
>
>> This patch lays down the foundation for the kernel memory component
>> of the Memory Controller.
>>
>> As of today, I am only laying down the following files:
>>
>> * memory.independent_kmem_limit
>> * memory.kmem.limit_in_bytes (currently ignored)
>> * memory.kmem.usage_in_bytes (always zero)
>>
>> Signed-off-by: Glauber Costa<glommer@parallels.com>
>> Reviewed-by: Kirill A. Shutemov<kirill@shutemov.name>
>> CC: Paul Menage<paul@paulmenage.org>
>> CC: Greg Thelen<gthelen@google.com>
>
> As I wrote, please CC Johannes and Michal Hocko for memcg related parts.
I forgot to add them to the patch itself, but they are in the CC list of
the messages.
So they did get the mail.
> A few questions.
> ==
>> + val = !!val;
>> +
>> + if (parent&& parent->use_hierarchy&&
>> + (val != parent->kmem_independent_accounting))
>> + return -EINVAL;
> ==
> Hm, why you check val != parent->kmem_independent_accounting ?
>
> if (parent&& parent->use_hierarchy)
> return -EINVAL;
> ?
Because I thought that making sure that everybody in the chain is
consistent, it will make things simpler for us. But I am happy to change
that if you prefer.
> BTW, you didn't check this cgroup has children or not.
> I think
>
> if (this_cgroup->use_hierarchy&&
> !list_empty(this_cgroup->childlen))
> return -EINVAL;
>
Noted.
> ==
>> + /*
>> + * TODO: We need to handle the case in which we are doing
>> + * independent kmem accounting as authorized by our parent,
>> + * but then our parent changes its parameter.
>> + */
>> + cgroup_lock();
>> + memcg->kmem_independent_accounting = val;
>> + cgroup_unlock();
>
> Do we need cgroup_lock() here ?
Well, I removed almost all instances of it from previous patches, so I
guess this one can go as well.
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