Re: [RFC][PATCH] Remove cgroup member from struct page (v3)

[KAMEZAWA Hiroyuki]

On Wed, 17 Sep 2008 20:57:54 -0700
Balbir Singh <balbir@xxxxxxxxxxxxxxxxxx> wrote:

> Andrew Morton wrote:

> > someone somewhere decided that (Aa + Bb) / Cc < 1.0.  What are the values
> > of A, B and C and where did they come from? ;)
> > 
> > (IOW, your changelog is in the category "sucky", along with 90% of the others)
> 
> Yes, I agree, to be honest we discussed the reasons on the mailing list and
> those should go to the changelog. I'll do that in the next version of the
> patches. These are early RFC patches, but the changelog does suck.
> 
IIRC, (Aa + Bb) / Cc < 1.0 discussion was following.

Because we have to maintain pointer to page_cgroup in radix-tree (ZONE_NORMAL)

1. memory usage will increase when memory cgroup is enabled.
   The amount memory usage increase just depends on the height of radix-tree.

2. memory usage will decrease when memory cgroup is disabled.
   This saves 4bytes per 4096bytes. (on x86-32)

Thanks,
-Kame  

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