linux-kernel - Re: [External] Re: [RFC PATCH 20/24] mm/hugetlb: Add a kernel parameter hugetlb_free

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Message-ID: <CAMZfGtVv_8GR7c4syah8PNH6FBS8H7FQesBYr_qQRQaUEgZbsQ@mail.gmail.com>
Date:   Wed, 16 Sep 2020 10:50:08 +0800
From:   Muchun Song <songmuchun@...edance.com>
To:     Randy Dunlap <rdunlap@...radead.org>
Cc:     Jonathan Corbet <corbet@....net>,
        Mike Kravetz <mike.kravetz@...cle.com>,
        Thomas Gleixner <tglx@...utronix.de>, mingo@...hat.com,
        bp@...en8.de, x86@...nel.org, hpa@...or.com,
        dave.hansen@...ux.intel.com, luto@...nel.org,
        Peter Zijlstra <peterz@...radead.org>, viro@...iv.linux.org.uk,
        Andrew Morton <akpm@...ux-foundation.org>, paulmck@...nel.org,
        mchehab+huawei@...nel.org, pawan.kumar.gupta@...ux.intel.com,
        oneukum@...e.com, anshuman.khandual@....com, jroedel@...e.de,
        almasrymina@...gle.com, David Rientjes <rientjes@...gle.com>,
        linux-doc@...r.kernel.org, LKML <linux-kernel@...r.kernel.org>,
        Linux Memory Management List <linux-mm@...ck.org>,
        linux-fsdevel@...r.kernel.org
Subject: Re: [External] Re: [RFC PATCH 20/24] mm/hugetlb: Add a kernel
 parameter hugetlb_free_vmemmap

On Wed, Sep 16, 2020 at 10:11 AM Randy Dunlap <rdunlap@...radead.org> wrote:
>
> Hi,
> Please see comments below.
>
> On 9/15/20 5:59 AM, Muchun Song wrote:
> > Add a kernel parameter hugetlb_free_vmemmap to disable the feature of
> > freeing unused vmemmap pages associated with each hugetlb page on boot.
> >
> > Signed-off-by: Muchun Song <songmuchun@...edance.com>
> > ---
> >  .../admin-guide/kernel-parameters.txt         |  9 ++++++++
> >  Documentation/admin-guide/mm/hugetlbpage.rst  |  3 +++
> >  mm/hugetlb.c                                  | 23 +++++++++++++++++++
> >  3 files changed, 35 insertions(+)
> >
> > diff --git a/Documentation/admin-guide/kernel-parameters.txt b/Documentation/admin-guide/kernel-parameters.txt
> > index 5debfe238027..69d18ef6f66b 100644
> > --- a/Documentation/admin-guide/kernel-parameters.txt
> > +++ b/Documentation/admin-guide/kernel-parameters.txt
> > @@ -1551,6 +1551,15 @@
> >                       Documentation/admin-guide/mm/hugetlbpage.rst.
> >                       Format: size[KMG]
> >
> > +     hugetlb_free_vmemmap=
> > +                     [KNL] When CONFIG_HUGETLB_PAGE_FREE_VMEMMAP is set,
> > +                     this disables freeing unused vmemmap pages associated
>
>                         this controls
>
> > +                     each HugeTLB page.
>
>                         with each HugeTLB page.
>
> > +                     Format: { on (default) | off }
> > +
> > +                     on:  enable the feature
> > +                     off: dosable the feature
>
>                              disable
>
> > +
> >       hung_task_panic=
> >                       [KNL] Should the hung task detector generate panics.
> >                       Format: 0 | 1
> > diff --git a/Documentation/admin-guide/mm/hugetlbpage.rst b/Documentation/admin-guide/mm/hugetlbpage.rst
> > index f7b1c7462991..7d6129ee97dd 100644
> > --- a/Documentation/admin-guide/mm/hugetlbpage.rst
> > +++ b/Documentation/admin-guide/mm/hugetlbpage.rst
> > @@ -145,6 +145,9 @@ default_hugepagesz
> >
> >       will all result in 256 2M huge pages being allocated.  Valid default
> >       huge page size is architecture dependent.
>
> insert blank line here.
>
> > +hugetlb_free_vmemmap
> > +     When CONFIG_HUGETLB_PAGE_FREE_VMEMMAP is set, this disables freeing
> > +     unused vmemmap pages associated each HugeTLB page.
> >
> >  When multiple huge page sizes are supported, ``/proc/sys/vm/nr_hugepages``
> >  indicates the current number of pre-allocated huge pages of the default size.
>

Thanks for your comments.

>
> --
> ~Randy
>


-- 
Yours,
Muchun