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From:   Muchun Song <songmuchun@bytedance.com>
Date:   Mon, 22 Nov 2021 12:21:32 +0800
Message-ID: <CAMZfGtV0JKcjVL0qGoYCQJ-LsXdng7Z2UjBym5hf_WM0LcYi=Q@mail.gmail.com>
Subject: Re: [PATCH v7 0/5] Free the 2nd vmemmap page associated with each
 HugeTLB page
To:     Mike Kravetz <mike.kravetz@oracle.com>,
        Andrew Morton <akpm@linux-foundation.org>,
        Oscar Salvador <osalvador@suse.de>,
        David Hildenbrand <david@redhat.com>,
        Michal Hocko <mhocko@suse.com>,
        Matthew Wilcox <willy@infradead.org>
Cc:     Jonathan Corbet <corbet@lwn.net>,
        Xiongchun duan <duanxiongchun@bytedance.com>,
        fam.zheng@bytedance.com, Muchun Song <smuchun@gmail.com>,
        Qi Zheng <zhengqi.arch@bytedance.com>,
        linux-doc@vger.kernel.org, LKML <linux-kernel@vger.kernel.org>,
        Linux Memory Management List <linux-mm@kvack.org>,
        "Song Bao Hua (Barry Song)" <song.bao.hua@hisilicon.com>,
        Barry Song <21cnbao@gmail.com>,
        Chen Huang <chenhuang5@huawei.com>,
        "Bodeddula, Balasubramaniam" <bodeddub@amazon.com>
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On Wed, Nov 10, 2021 at 2:18 PM Muchun Song <songmuchun@bytedance.com> wrote:
>
> On Tue, Nov 9, 2021 at 3:33 AM Mike Kravetz <mike.kravetz@oracle.com> wrote:
> >
> > On 11/8/21 12:16 AM, Muchun Song wrote:
> > > On Mon, Nov 1, 2021 at 11:22 AM Muchun Song <songmuchun@bytedance.com> wrote:
> > >>
> > >> This series can minimize the overhead of struct page for 2MB HugeTLB pages
> > >> significantly. It further reduces the overhead of struct page by 12.5% for
> > >> a 2MB HugeTLB compared to the previous approach, which means 2GB per 1TB
> > >> HugeTLB. It is a nice gain. Comments and reviews are welcome. Thanks.
> > >>
> > >
> > > Hi,
> > >
> > > Ping guys. Does anyone have any comments or suggestions
> > > on this series?
> > >
> > > Thanks.
> > >
> >
> > I did look over the series earlier.  I have no issue with the hugetlb and
> > vmemmap modifications as they are enhancements to the existing
> > optimizations.  My primary concern is the (small) increased overhead
> > for the helpers as outlined in your cover letter.  Since these helpers
> > are not limited to hugetlb and used throughout the kernel, I would
> > really like to get comments from others with a better understanding of
> > the potential impact.
>
> Thanks Mike. I'd like to hear others' comments about this as well.
> From my point of view, maybe the (small) overhead is acceptable
> since it only affects the head page, however Matthew Wilcox's folio
> series could reduce this situation as well.
>
> Looking forward to others' comments.
>

Ping guys.

Hi Andrew,

Do you have any suggestions on this series to move it on?

Thanks.