From: Mike Kravetz <mike.kravetz@oracle.com>
To: Baolin Wang <baolin.wang@linux.alibaba.com>
Cc: linux-kernel@vger.kernel.org, linux-mm@kvack.org,
Muchun Song <songmuchun@bytedance.com>,
Michal Hocko <mhocko@suse.com>, Peter Xu <peterx@redhat.com>,
Naoya Horiguchi <naoya.horiguchi@linux.dev>,
James Houghton <jthoughton@google.com>,
Mina Almasry <almasrymina@google.com>,
"Aneesh Kumar K . V" <aneesh.kumar@linux.vnet.ibm.com>,
Anshuman Khandual <anshuman.khandual@arm.com>,
Paul Walmsley <paul.walmsley@sifive.com>,
Christian Borntraeger <borntraeger@linux.ibm.com>,
Andrew Morton <akpm@linux-foundation.org>
Subject: Re: [RFC PATCH 1/3] hugetlb: skip to end of PT page mapping when pte not present
Date: Wed, 15 Jun 2022 14:22:34 -0700 [thread overview]
Message-ID: <YqpNmsLrbCowS1IE@monkey> (raw)
In-Reply-To: <437e45c5-c46a-46f4-f9cf-d8c2397c988d@linux.alibaba.com>
On 05/30/22 18:10, Baolin Wang wrote:
>
>
> On 5/28/2022 6:58 AM, Mike Kravetz wrote:
> > HugeTLB address ranges are linearly scanned during fork, unmap and
> > remap operations. If a non-present entry is encountered, the code
> > currently continues to the next huge page aligned address. However,
> > a non-present entry implies that the page table page for that entry
> > is not present. Therefore, the linear scan can skip to the end of
> > range mapped by the page table page. This can speed operations on
> > large sparsely populated hugetlb mappings.
> >
> > Create a new routine hugetlb_mask_last_hp() that will return an
> > address mask. When the mask is ORed with an address, the result
> > will be the address of the last huge page mapped by the associated
> > page table page. Use this mask to update addresses in routines which
> > linearly scan hugetlb address ranges when a non-present pte is
> > encountered.
> >
> > hugetlb_mask_last_hp is related to the implementation of huge_pte_offset
> > as hugetlb_mask_last_hp is called when huge_pte_offset returns NULL.
> > This patch only provides a complete hugetlb_mask_last_hp implementation
> > when CONFIG_ARCH_WANT_GENERAL_HUGETLB is defined. Architectures which
> > provide their own versions of huge_pte_offset can also provide their own
> > version of hugetlb_mask_last_hp.
>
> I tested on my ARM64 machine with implementing arm64 specific
> hugetlb_mask_last_hp() as below, and it works well.
>
> Just a few nits inline, otherwise looks good to me.
> Tested-by: Baolin Wang <baolin.wang@linux.alibaba.com>
> Reviewed-by: Baolin Wang <baolin.wang@linux.alibaba.com>
>
> diff --git a/arch/arm64/mm/hugetlbpage.c b/arch/arm64/mm/hugetlbpage.c
> index d93ba128a2b0..e04a097ffcc4 100644
> --- a/arch/arm64/mm/hugetlbpage.c
> +++ b/arch/arm64/mm/hugetlbpage.c
> @@ -376,6 +376,28 @@ pte_t *huge_pte_offset(struct mm_struct *mm,
> return NULL;
> }
>
> +unsigned long hugetlb_mask_last_hp(struct hstate *h)
> +{
> + unsigned long hp_size = huge_page_size(h);
> +
> + switch (hp_size) {
> + case P4D_SIZE:
> + return PGDIR_SIZE - P4D_SIZE;
> + case PUD_SIZE:
> + return P4D_SIZE - PUD_SIZE;
> + case CONT_PMD_SIZE:
> + return PUD_SIZE - CONT_PMD_SIZE;
> + case PMD_SIZE:
> + return PUD_SIZE - PMD_SIZE;
> + case CONT_PTE_SIZE:
> + return PMD_SIZE - CONT_PTE_SIZE;
> + default:
> + break;
> + }
> +
> + return ~(0UL);
> +}
Hello Baolin,
Would you mind sending this as a proper patch with commit message and
'Signed-off-by:'? I would like to include it in the upcoming patch series.
--
Mike Kravetz
next prev parent reply other threads:[~2022-06-15 21:22 UTC|newest]
Thread overview: 20+ messages / expand[flat|nested] mbox.gz Atom feed top
2022-05-27 22:58 [RFC PATCH 0/3] hugetlb: speed up linear address scanning Mike Kravetz
2022-05-27 22:58 ` [RFC PATCH 1/3] hugetlb: skip to end of PT page mapping when pte not present Mike Kravetz
2022-05-30 10:10 ` Baolin Wang
2022-05-31 16:56 ` Mike Kravetz
2022-06-15 21:22 ` Mike Kravetz [this message]
2022-06-16 3:48 ` Baolin Wang
2022-05-30 19:56 ` Peter Xu
2022-05-31 2:04 ` Muchun Song
2022-05-31 17:05 ` Mike Kravetz
2022-06-01 6:58 ` Anshuman Khandual
2022-05-31 17:00 ` Mike Kravetz
2022-06-15 17:27 ` Mike Kravetz
2022-06-15 17:51 ` Peter Xu
2022-05-27 22:58 ` [RFC PATCH 2/3] hugetlb: do not update address in huge_pmd_unshare Mike Kravetz
2022-05-30 10:14 ` Baolin Wang
2022-05-30 15:36 ` Muchun Song
2022-05-31 17:06 ` Mike Kravetz
2022-05-27 22:58 ` [RFC PATCH 3/3] hugetlb: Lazy page table copies in fork() Mike Kravetz
2022-05-31 17:25 ` David Hildenbrand
2022-06-01 5:20 ` Muchun Song
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