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SubjectRe: [PATCH 3/9] bio-cgroup controller
On Fri, 17 Apr 2009 17:00:16 +0900
KAMEZAWA Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com> wrote:

> On Fri, 17 Apr 2009 16:22:01 +0900 (JST)
> Ryo Tsuruta <ryov@valinux.co.jp> wrote:
>
> > In the case where the bio-cgroup data is allocated dynamically,
> > - Sometimes quite a large amount of memory get marked dirty.
> > In this case it requires more kernel memory than that of the
> > current implementation.
> > - The operation is expansive due to memory allocations and exclusive
> > controls by such as spinlocks.
> >
> > In the case where the bio-cgroup data is allocated by delayed allocation,
> > - It makes the operation complicated and expensive, because
> > sometimes a bio has to be created in the context of other
> > processes, such as aio and swap-out operation.
> >
> > I'd prefer a simple and lightweight implementation. bio-cgroup only
> > needs 4bytes unlike memory controller. The reason why bio-cgroup chose
> > this approach is to minimize the overhead.
> >
> My point is, plz do your best to reduce memory usage here. You increase
> size of page_cgroup just because you cannot increase size of struct page.
> It's not be sane reason to increase size of this object.
> It's a cheat in my point of view.
>

Can't this work sanely ?
Hmm, endian is obstacle ?
==
sturct page_cgroup {
union {
struct {
unsigned long memcg_field:16;
unsigned long blockio_field:16;
} field;
unsigned long flags; /* unsigned long is not 32bits */
} flags;
}
==

Thanks,
-Kame







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