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SubjectRe: [-mm] Add an owner to the mm_struct (v8)
Andrew Morton wrote:
> On Fri, 04 Apr 2008 13:35:44 +0530
> Balbir Singh <balbir@linux.vnet.ibm.com> wrote:
>
>> 1. Add mm->owner change callbacks using cgroups
>>
>> ...
>>
>> +config MM_OWNER
>> + bool "Enable ownership of mm structure"
>> + help
>> + This option enables mm_struct's to have an owner. The advantage
>> + of this approach is that it allows for several independent memory
>> + based cgroup controllers to co-exist independently without too
>> + much space overhead
>> +
>> + This feature adds fork/exit overhead. So enable this only if
>> + you need resource controllers
>
> Do we really want to offer this option to people? It's rather a low-level
> thing and it's likely to cause more confusion than it's worth. Remember
> that most kernels get to our users via kernel vendors - to what will they
> be setting this config option?
>

I suspect that this kernel option will not be explicitly set it. This option
will be selected by other config options (memory controller, swap namespace,
revoke*)

>> config CGROUP_MEM_RES_CTLR
>> bool "Memory Resource Controller for Control Groups"
>> depends on CGROUPS && RESOURCE_COUNTERS
>> + select MM_OWNER
>
> Presumably they'll always be setting it to "y" if they are enabling cgroups
> at all.
>
>> --- linux-2.6.25-rc8/kernel/cgroup.c~memory-controller-add-mm-owner 2008-04-03 22:43:27.000000000 +0530
>> +++ linux-2.6.25-rc8-balbir/kernel/cgroup.c 2008-04-03 22:43:27.000000000 +0530
>> @@ -118,6 +118,7 @@ static int root_count;
>> * be called.
>> */
>> static int need_forkexit_callback;
>> +static int need_mm_owner_callback;
>
> I suppose these should be __read_mostly.
>

Yes, good point. I'll send out v9 with this fix.

--
Warm Regards,
Balbir Singh
Linux Technology Center
IBM, ISTL


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