linux-kernel - Re: [PATCH v1 2/3] mm/memory_hotplug: don't shuffle complete zone when onlining memory

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Message-ID: <CAPcyv4hjxyyxVyZbAYoXX2TM3mHF6e4VneVVcmVU+_Q4n9CxzQ@mail.gmail.com>
Date:   Tue, 16 Jun 2020 10:00:39 -0700
From:   Dan Williams <dan.j.williams@...el.com>
To:     Michal Hocko <mhocko@...nel.org>
Cc:     David Hildenbrand <david@...hat.com>,
        Linux Kernel Mailing List <linux-kernel@...r.kernel.org>,
        Linux MM <linux-mm@...ck.org>,
        Andrew Morton <akpm@...ux-foundation.org>,
        Alexander Duyck <alexander.h.duyck@...ux.intel.com>,
        Dave Hansen <dave.hansen@...ux.intel.com>,
        Kees Cook <keescook@...omium.org>,
        Mel Gorman <mgorman@...hsingularity.net>
Subject: Re: [PATCH v1 2/3] mm/memory_hotplug: don't shuffle complete zone
 when onlining memory

On Tue, Jun 16, 2020 at 5:51 AM Michal Hocko <mhocko@...nel.org> wrote:
>
> On Tue 16-06-20 13:52:12, David Hildenbrand wrote:
> > Commit e900a918b098 ("mm: shuffle initial free memory to improve
> > memory-side-cache utilization") introduced shuffling of free pages
> > during system boot and whenever we online memory blocks.
> >
> > However, whenever we online memory blocks, all pages that will be
> > exposed to the buddy end up getting freed via __free_one_page(). In the
> > general case, we free these pages in MAX_ORDER - 1 chunks, which
> > corresponds to the shuffle order.
> >
> > Inside __free_one_page(), we will already shuffle the newly onlined pages
> > using "to_tail = shuffle_pick_tail();". Drop explicit zone shuffling on
> > memory hotplug.
> >
> > Note: When hotplugging a DIMM, each memory block (e.g., 128MB .. 2G on
> > x86-64) will get onlined individually, resulting in a shuffle_zone() for
> > every memory block getting onlined.
> >
> > Cc: Andrew Morton <akpm@...ux-foundation.org>
> > Cc: Alexander Duyck <alexander.h.duyck@...ux.intel.com>
> > Cc: Dan Williams <dan.j.williams@...el.com>
> > Cc: Michal Hocko <mhocko@...e.com>
> > Cc: Dave Hansen <dave.hansen@...ux.intel.com>
> > Cc: Kees Cook <keescook@...omium.org>
> > Cc: Mel Gorman <mgorman@...hsingularity.net>
> > Signed-off-by: David Hildenbrand <david@...hat.com>
>
> Acked-by: Michal Hocko <mhocko@...e.com>

Nacked-by: Dan Williams <dan.j.williams@...el.com>

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