Messages in this thread | | | Date | Mon, 08 Sep 2008 21:18:37 -0700 | From | Balbir Singh <> | Subject | Re: [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
| |