Re: [patch 1/3] mm: embed the memcg pointer directly into struct page

[Konstantin Khlebnikov]

On Sun, Nov 2, 2014 at 6:15 AM, Johannes Weiner <hannes@xxxxxxxxxxx> wrote:
> Memory cgroups used to have 5 per-page pointers.  To allow users to
> disable that amount of overhead during runtime, those pointers were
> allocated in a separate array, with a translation layer between them
> and struct page.
>
> There is now only one page pointer remaining: the memcg pointer, that
> indicates which cgroup the page is associated with when charged.  The
> complexity of runtime allocation and the runtime translation overhead
> is no longer justified to save that *potential* 0.19% of memory.  With
> CONFIG_SLUB, page->mem_cgroup actually sits in the doubleword padding
> after the page->private member and doesn't even increase struct page,
> and then this patch actually saves space.  Remaining users that care
> can still compile their kernels without CONFIG_MEMCG.
>
>    text    data     bss     dec     hex     filename
> 8828345 1725264  983040 11536649 b00909  vmlinux.old
> 8827425 1725264  966656 11519345 afc571  vmlinux.new
>
> Signed-off-by: Johannes Weiner <hannes@xxxxxxxxxxx>

Great! Never thought I'd see this. =)

Acked-by: Konstantin Khlebnikov <koct9i@xxxxxxxxx>


> ---
>  include/linux/memcontrol.h  |   6 +-
>  include/linux/mm_types.h    |   5 +
>  include/linux/mmzone.h      |  12 --
>  include/linux/page_cgroup.h |  53 --------
>  init/main.c                 |   7 -
>  mm/memcontrol.c             | 124 +++++------------
>  mm/page_alloc.c             |   2 -
>  mm/page_cgroup.c            | 319 --------------------------------------------
>  8 files changed, 41 insertions(+), 487 deletions(-)
>
> diff --git a/include/linux/memcontrol.h b/include/linux/memcontrol.h
> index d4575a1d6e99..dafba59b31b4 100644



> the body to majordomo@xxxxxxxxxx  For more info on Linux MM,
> see: http://www.linux-mm.org/ .
> Don't email: <a href=mailto:"dont@xxxxxxxxx";> email@xxxxxxxxx </a>
--
To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
the body of a message to majordomo@xxxxxxxxxxxxxxx
More majordomo info at  http://vger.kernel.org/majordomo-info.html
Please read the FAQ at  http://www.tux.org/lkml/