Hi Glauber,

On 01/09/2013 11:09 PM, Glauber Costa wrote:

quoted

We try to make all page_cgroup allocations local to the node they are describing
now. If the memory is the first memory onlined in this node, we will allocate
it from the other node.

For example, node1 has 4 memory blocks: 8-11, and we online it from 8 to 11
1. memory block 8, page_cgroup allocations are in the other nodes
2. memory block 9, page_cgroup allocations are in memory block 8

So we should offline memory block 9 first. But we don't know in which order
the user online the memory block.

I think we can modify memcg like this:
allocate the memory from the memory block they are describing

I am not sure it is OK to do so.

I don't see a reason why not.

I'm not sure, but if we do this, we could bring in a fragment for each
memory block (a memory section, 128MB, right?). Is this a problem when
we use large page (such as 1GB page) ?

Even if not, will these fragments make any bad effects ?

Thank. :)

You would have to tweak a bit the lookup function for page_cgroup, but
assuming you will always have the pfns and limits, it should be easy to do.

I think the only tricky part is that today we have a single
node_page_cgroup, and we would of course have to have one per memory
block. My assumption is that the number of memory blocks is limited and
likely not very big. So even a static array would do.

Kamezawa, do you have any input in here?

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