lkml.org 
[lkml]   [2008]   [Sep]   [9]   [last100]   RSS Feed
Views: [wrap][no wrap]   [headers]  [forward] 
 
Messages in this thread
/
Date
From
SubjectRe: [RFC][PATCH] Remove cgroup member from struct page
KAMEZAWA Hiroyuki wrote:
> On Mon, 8 Sep 2008 20:58:10 +0530
> Balbir Singh <balbir@linux.vnet.ibm.com> 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)
> to getting address of page_cgroup.

What address calculation do we need, sorry I don't recollect it.

But page_cgroup itself consumes 32bytes
> 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.
>

This is on top of the suggested approach above?

> How do you think ?
>

I don't like the approach.

--
Balbir


\
 
 \ /
  Last update: 2008-09-09 06:37    [W:0.103 / U:0.072 seconds]
©2003-2020 Jasper Spaans|hosted at Digital Ocean and TransIP|Read the blog|Advertise on this site