linux-kernel - Re: [PATCH v9 1/3] mm: Shuffle initial free memory to improve memory-side-cache utilization

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Message-Id: <20190130064856.GB17937@rapoport-lnx>
Date:   Wed, 30 Jan 2019 08:48:56 +0200
From:   Mike Rapoport <rppt@...ux.ibm.com>
To:     Dan Williams <dan.j.williams@...el.com>
Cc:     akpm@...ux-foundation.org, Michal Hocko <mhocko@...e.com>,
        Dave Hansen <dave.hansen@...ux.intel.com>,
        Kees Cook <keescook@...omium.org>, linux-mm@...ck.org,
        linux-kernel@...r.kernel.org
Subject: Re: [PATCH v9 1/3] mm: Shuffle initial free memory to improve
 memory-side-cache utilization

On Tue, Jan 29, 2019 at 09:02:16PM -0800, Dan Williams wrote:
> Randomization of the page allocator improves the average utilization of
> a direct-mapped memory-side-cache. Memory side caching is a platform
> capability that Linux has been previously exposed to in HPC
> (high-performance computing) environments on specialty platforms. In
> that instance it was a smaller pool of high-bandwidth-memory relative to
> higher-capacity / lower-bandwidth DRAM. Now, this capability is going to
> be found on general purpose server platforms where DRAM is a cache in
> front of higher latency persistent memory [1].

[ ... ]
 
> Cc: Michal Hocko <mhocko@...e.com>
> Cc: Dave Hansen <dave.hansen@...ux.intel.com>
> Cc: Mike Rapoport <rppt@...ux.ibm.com>
> Reviewed-by: Kees Cook <keescook@...omium.org>
> Signed-off-by: Dan Williams <dan.j.williams@...el.com>
> ---
>  include/linux/list.h    |   17 ++++
>  include/linux/mmzone.h  |    4 +
>  include/linux/shuffle.h |   45 +++++++++++
>  init/Kconfig            |   23 ++++++
>  mm/Makefile             |    7 ++
>  mm/memblock.c           |    1 
>  mm/memory_hotplug.c     |    3 +
>  mm/page_alloc.c         |    6 +-
>  mm/shuffle.c            |  188 +++++++++++++++++++++++++++++++++++++++++++++++
>  9 files changed, 292 insertions(+), 2 deletions(-)
>  create mode 100644 include/linux/shuffle.h
>  create mode 100644 mm/shuffle.c

...

> diff --git a/mm/memblock.c b/mm/memblock.c
> index 022d4cbb3618..c0cfbfae4a03 100644
> --- a/mm/memblock.c
> +++ b/mm/memblock.c
> @@ -17,6 +17,7 @@
>  #include <linux/poison.h>
>  #include <linux/pfn.h>
>  #include <linux/debugfs.h>
> +#include <linux/shuffle.h>

Nit: does not seem to be required

>  #include <linux/kmemleak.h>
>  #include <linux/seq_file.h>
>  #include <linux/memblock.h>

-- 
Sincerely yours,
Mike.