KAMEZAWA Hiroyuki wrote:

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> On Mon, 8 Sep 2008 20:58:10 +0530

> Balbir Singh  wrote:

>> Sorry for the delay in sending out the new patch, I am traveling and

>> thus a little less responsive. Here is the update patch

>>

>>

> Hmm.. I've considered this approach for a while and my answer is that

> this is not what you really want.

>

> Because you just moves the placement of pointer from memmap to

> radix_tree both in GFP_KERNEL, total kernel memory usage is not changed.

Agreed, but we do reduce the sizeof(struct page) without adding on to

page_cgroup's size. So why don't we want this?
> So, at least, you have to add some address calculation (as I did in March)

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> to getting address of page_cgroup.

What address calculation do we need, sorry I don't recollect it.
 But page_cgroup itself consumes 32bytes

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> per page. Then.....

>

> My proposal to 32bit system is following

>  - remove page_cgroup completely.

>    - As a result, there is no per-cgroup lru. But it will not be bad

>      bacause the number of cgroups and pages are not big.

>      just a trade-off between kernel-memory-space v.s. speed.

32 bit systems with PAE can support quite a lot of memory, so I am not sure I

agree. I don't like this approach
>    - Removing page_cgroup and just remember address of mem_cgroup per page.

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> 

This is on top of the suggested approach above?
> How do you think ?

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> 

I don't like the approach.
--

	Balbir

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