From: Baolin Wang <baolin.wang@linux.alibaba.com>
To: Mike Kravetz <mike.kravetz@oracle.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: Thu, 16 Jun 2022 11:48:56 +0800 [thread overview]
Message-ID: <255ccf96-2c12-9ca0-9f8b-8a8461253952@linux.alibaba.com> (raw)
In-Reply-To: <YqpNmsLrbCowS1IE@monkey>
On 6/16/2022 5:22 AM, Mike Kravetz wrote:
> 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.
Sure. I've sent it out [1], and please fold it into your series. Thanks.
[1]
https://lore.kernel.org/all/7256dbe078d7231f45b0f47c2c52a3bd3aa10da7.1655350193.git.baolin.wang@linux.alibaba.com/
next prev parent reply other threads:[~2022-06-16 3:48 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
2022-06-16 3:48 ` Baolin Wang [this message]
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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