On 02/23/2012 04:18 PM, Ying Han wrote:

On Tue, Feb 21, 2012 at 3:34 AM, Glauber Costa[off-list ref]  wrote:

quoted

This is a first structured approach to tracking general kernel
memory within the memory controller. Please tell me what you think.

As previously proposed, one has the option of keeping kernel memory
accounted separatedly, or together with the normal userspace memory.
However, this time I made the option to, in this later case, bill
the memory directly to memcg->res. It has the disadvantage that it becomes
complicated to know which memory came from user or kernel, but OTOH,
it does not create any overhead of drawing from multiple res_counters
at read time. (and if you want them to be joined, you probably don't care)

Keeping one counter for user and kernel pages makes it easier for
admins to configure the system. About reporting, we should still
report the user and kernel memory separately. It will be extremely
useful when diagnosing the system like heavily memory pressure or OOM.

It will also make us charge two different res_counters, which is not a 
cheap operation.

I was wondering if we can do something smarter within the res_counter 
itself to avoid taking locks for two different res_counters in the 
charge path?

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