From: Muchun Song <songmuchun@bytedance.com>
To: David Hildenbrand <david@redhat.com>
Cc: Jonathan Corbet <corbet@lwn.net>,
Mike Kravetz <mike.kravetz@oracle.com>,
Thomas Gleixner <tglx@linutronix.de>,
mingo@redhat.com, bp@alien8.de, x86@kernel.org, hpa@zytor.com,
dave.hansen@linux.intel.com, luto@kernel.org,
Peter Zijlstra <peterz@infradead.org>,
viro@zeniv.linux.org.uk,
Andrew Morton <akpm@linux-foundation.org>,
paulmck@kernel.org, mchehab+huawei@kernel.org,
pawan.kumar.gupta@linux.intel.com,
Randy Dunlap <rdunlap@infradead.org>,
oneukum@suse.com, anshuman.khandual@arm.com, jroedel@suse.de,
Mina Almasry <almasrymina@google.com>,
David Rientjes <rientjes@google.com>,
Matthew Wilcox <willy@infradead.org>,
Oscar Salvador <osalvador@suse.de>,
Michal Hocko <mhocko@suse.com>,
"Song Bao Hua (Barry Song)" <song.bao.hua@hisilicon.com>,
Xiongchun duan <duanxiongchun@bytedance.com>,
linux-doc@vger.kernel.org, LKML <linux-kernel@vger.kernel.org>,
Linux Memory Management List <linux-mm@kvack.org>,
linux-fsdevel <linux-fsdevel@vger.kernel.org>
Subject: Re: [External] Re: [PATCH v7 03/15] mm/hugetlb: Introduce a new config HUGETLB_PAGE_FREE_VMEMMAP
Date: Mon, 7 Dec 2020 20:42:29 +0800 [thread overview]
Message-ID: <CAMZfGtVnw8aJWceLM1UerkAZzcjkObb-ZrCE_Jj6w3EUR=UN3Q@mail.gmail.com> (raw)
In-Reply-To: <2ec1d360-c8c8-eb7b-2afe-b75ee61cfcea@redhat.com>
On Mon, Dec 7, 2020 at 8:19 PM David Hildenbrand <david@redhat.com> wrote:
>
> On 30.11.20 16:18, Muchun Song wrote:
> > The purpose of introducing HUGETLB_PAGE_FREE_VMEMMAP is to configure
> > whether to enable the feature of freeing unused vmemmap associated
> > with HugeTLB pages. And this is just for dependency check. Now only
> > support x86.
>
> x86 - i386 and x86-64? (I assume the latter only ;) )
Yeah, you are right. Only the latter support SPARSEMEM_VMEMMAP.
>
> >
> > Signed-off-by: Muchun Song <songmuchun@bytedance.com>
> > ---
> > arch/x86/mm/init_64.c | 2 +-
> > fs/Kconfig | 14 ++++++++++++++
> > 2 files changed, 15 insertions(+), 1 deletion(-)
> >
> > diff --git a/arch/x86/mm/init_64.c b/arch/x86/mm/init_64.c
> > index 0a45f062826e..0435bee2e172 100644
> > --- a/arch/x86/mm/init_64.c
> > +++ b/arch/x86/mm/init_64.c
> > @@ -1225,7 +1225,7 @@ static struct kcore_list kcore_vsyscall;
> >
> > static void __init register_page_bootmem_info(void)
> > {
> > -#ifdef CONFIG_NUMA
> > +#if defined(CONFIG_NUMA) || defined(CONFIG_HUGETLB_PAGE_FREE_VMEMMAP)
> > int i;
> >
>
> Why does this hunk belong into this patch? Looks like this should go
> into another patch.
Of course can. But Mike suggests that it is better to use it when
introducing a new config. Because this config depends on
HAVE_BOOTMEM_INFO_NODE. And register_page_bootmem_info
is aimed to register bootmem info. So maybe it is reasonable from
this point of view. What is your opinion?
>
> > for_each_online_node(i)
> > diff --git a/fs/Kconfig b/fs/Kconfig
> > index 976e8b9033c4..4961dd488444 100644
> > --- a/fs/Kconfig
> > +++ b/fs/Kconfig
> > @@ -245,6 +245,20 @@ config HUGETLBFS
> > config HUGETLB_PAGE
> > def_bool HUGETLBFS
> >
> > +config HUGETLB_PAGE_FREE_VMEMMAP
> > + def_bool HUGETLB_PAGE
> > + depends on X86
> > + depends on SPARSEMEM_VMEMMAP
> > + depends on HAVE_BOOTMEM_INFO_NODE
> > + help
> > + When using HUGETLB_PAGE_FREE_VMEMMAP, the system can save up some
> > + memory from pre-allocated HugeTLB pages when they are not used.
> > + 6 pages per 2MB HugeTLB page and 4094 per 1GB HugeTLB page.
>
> Calculations only apply to 4k base pages, no?
No, if the base page is not 4k, we also can free 6 pages.
For example:
If the base page size is 64k, the PMD huge page size is 512MB. We also
can free 6 pages(64k * 6) vmemmap. But maybe I should document this.
Thanks.
> (maybe generalize this a
> bit or mention 4k base pages - I'm pretty sure we'll see the "depends on
> X86" part fairly soon if this goes upstream)
Yeah, it can be easy to adapt to different architectures. :)
>
>
> --
> Thanks,
>
> David / dhildenb
>
--
Yours,
Muchun
next prev parent reply other threads:[~2020-12-07 12:43 UTC|newest]
Thread overview: 49+ messages / expand[flat|nested] mbox.gz Atom feed top
2020-11-30 15:18 [PATCH v7 00/15] Free some vmemmap pages of hugetlb page Muchun Song
2020-11-30 15:18 ` [PATCH v7 01/15] mm/memory_hotplug: Move bootmem info registration API to bootmem_info.c Muchun Song
2020-12-07 12:12 ` David Hildenbrand
2020-11-30 15:18 ` [PATCH v7 02/15] mm/memory_hotplug: Move {get,put}_page_bootmem() " Muchun Song
2020-12-07 12:14 ` David Hildenbrand
2020-12-07 12:16 ` [External] " Muchun Song
2020-11-30 15:18 ` [PATCH v7 03/15] mm/hugetlb: Introduce a new config HUGETLB_PAGE_FREE_VMEMMAP Muchun Song
2020-12-07 12:19 ` David Hildenbrand
2020-12-07 12:42 ` Muchun Song [this message]
2020-12-07 12:47 ` [External] " David Hildenbrand
2020-12-07 13:22 ` Muchun Song
2020-11-30 15:18 ` [PATCH v7 04/15] mm/hugetlb: Introduce nr_free_vmemmap_pages in the struct hstate Muchun Song
2020-12-07 12:36 ` David Hildenbrand
2020-12-07 13:11 ` [External] " Muchun Song
2020-12-09 8:54 ` David Hildenbrand
2020-12-09 9:27 ` Muchun Song
2020-11-30 15:18 ` [PATCH v7 05/15] mm/bootmem_info: Introduce {free,prepare}_vmemmap_page() Muchun Song
2020-12-07 12:39 ` David Hildenbrand
2020-12-07 13:23 ` [External] " Muchun Song
2020-12-09 7:36 ` Muchun Song
2020-12-09 8:49 ` David Hildenbrand
2020-12-09 9:25 ` Muchun Song
2020-12-09 9:32 ` David Hildenbrand
2020-12-09 9:43 ` Muchun Song
2020-11-30 15:18 ` [PATCH v7 06/15] mm/hugetlb: Disable freeing vmemmap if struct page size is not power of two Muchun Song
2020-12-09 9:57 ` David Hildenbrand
2020-12-09 10:03 ` [External] " Muchun Song
2020-12-09 10:06 ` David Hildenbrand
2020-12-09 10:10 ` David Hildenbrand
2020-12-09 10:16 ` Muchun Song
2020-12-09 15:13 ` Muchun Song
2020-12-09 15:47 ` David Hildenbrand
2020-12-09 15:50 ` Muchun Song
2020-12-09 10:10 ` Muchun Song
2020-11-30 15:18 ` [PATCH v7 07/15] x86/mm/64: Disable PMD page mapping of vmemmap Muchun Song
2020-11-30 15:18 ` [PATCH v7 08/15] mm/hugetlb: Free the vmemmap pages associated with each hugetlb page Muchun Song
2020-11-30 15:18 ` [PATCH v7 09/15] mm/hugetlb: Defer freeing of HugeTLB pages Muchun Song
2020-11-30 15:18 ` [PATCH v7 10/15] mm/hugetlb: Allocate the vmemmap pages associated with each hugetlb page Muchun Song
2020-11-30 15:18 ` [PATCH v7 11/15] mm/hugetlb: Set the PageHWPoison to the raw error page Muchun Song
2020-11-30 15:18 ` [PATCH v7 12/15] mm/hugetlb: Flush work when dissolving hugetlb page Muchun Song
2020-11-30 15:18 ` [PATCH v7 13/15] mm/hugetlb: Add a kernel parameter hugetlb_free_vmemmap Muchun Song
2020-12-04 0:01 ` Song Bao Hua (Barry Song)
2020-11-30 15:18 ` [PATCH v7 14/15] mm/hugetlb: Gather discrete indexes of tail page Muchun Song
2020-11-30 15:18 ` [PATCH v7 15/15] mm/hugetlb: Add BUILD_BUG_ON to catch invalid usage of tail struct page Muchun Song
2020-12-03 8:35 ` [PATCH v7 00/15] Free some vmemmap pages of hugetlb page Muchun Song
2020-12-03 23:48 ` Mike Kravetz
2020-12-04 3:39 ` [External] " Muchun Song
2020-12-07 18:38 ` Oscar Salvador
2020-12-08 2:26 ` Muchun Song
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