From: Michal Hocko <mhocko@suse.com>
To: Zi Yan <ziy@nvidia.com>
Cc: linux-mm@kvack.org,
"Kirill A . Shutemov" <kirill.shutemov@linux.intel.com>,
Roman Gushchin <guro@fb.com>, Rik van Riel <riel@surriel.com>,
Matthew Wilcox <willy@infradead.org>,
Shakeel Butt <shakeelb@google.com>,
Yang Shi <shy828301@gmail.com>, Jason Gunthorpe <jgg@nvidia.com>,
Mike Kravetz <mike.kravetz@oracle.com>,
David Hildenbrand <david@redhat.com>,
William Kucharski <william.kucharski@oracle.com>,
Andrea Arcangeli <aarcange@redhat.com>,
John Hubbard <jhubbard@nvidia.com>,
David Nellans <dnellans@nvidia.com>,
linux-kernel@vger.kernel.org
Subject: Re: [RFC PATCH v2 00/30] 1GB PUD THP support on x86_64
Date: Wed, 30 Sep 2020 13:55:05 +0200 [thread overview]
Message-ID: <20200930115505.GT2277@dhcp22.suse.cz> (raw)
In-Reply-To: <20200928175428.4110504-1-zi.yan@sent.com>
On Mon 28-09-20 13:53:58, Zi Yan wrote:
> From: Zi Yan <ziy@nvidia.com>
>
> Hi all,
>
> This patchset adds support for 1GB PUD THP on x86_64. It is on top of
> v5.9-rc5-mmots-2020-09-18-21-23. It is also available at:
> https://github.com/x-y-z/linux-1gb-thp/tree/1gb_thp_v5.9-rc5-mmots-2020-09-18-21-23
>
> Other than PUD THP, we had some discussion on generating THPs and contiguous
> physical memory via a synchronous system call [0]. I am planning to send out a
> separate patchset on it later, since I feel that it can be done independently of
> PUD THP support.
While the technical challenges for the kernel implementation can be
discussed before the user API is decided I believe we cannot simply add
something now and then decide about a proper interface. I have raised
few basic questions we should should find answers for before the any
interface is added. Let me copy them here for easier reference
- THP allocation time - #PF and/or madvise context
- lazy/sync instantiation
- huge page sizes controllable by the userspace?
- aggressiveness - how hard to try
- internal fragmentation - allow to create THPs on sparsely or unpopulated
ranges
- do we need some sort of access control or privilege check as some THPs
would be a really scarce (like those that require pre-reservation).
--
Michal Hocko
SUSE Labs
next prev parent reply other threads:[~2020-09-30 11:55 UTC|newest]
Thread overview: 56+ messages / expand[flat|nested] mbox.gz Atom feed top
2020-09-28 17:53 [RFC PATCH v2 00/30] 1GB PUD THP support on x86_64 Zi Yan
2020-09-28 17:53 ` [RFC PATCH v2 01/30] mm/pagewalk: use READ_ONCE when reading the PUD entry unlocked Zi Yan
2020-09-28 17:54 ` [RFC PATCH v2 02/30] mm: pagewalk: use READ_ONCE when reading the PMD " Zi Yan
2020-09-28 17:54 ` [RFC PATCH v2 03/30] mm: thp: use single linked list for THP page table page deposit Zi Yan
2020-09-28 19:34 ` Matthew Wilcox
2020-09-28 20:34 ` Zi Yan
2020-09-28 17:54 ` [RFC PATCH v2 04/30] mm: add new helper functions to allocate one PMD page with 512 PTE pages Zi Yan
2020-09-28 17:54 ` [RFC PATCH v2 05/30] mm: thp: add page table deposit/withdraw functions for PUD THP Zi Yan
2020-09-28 17:54 ` [RFC PATCH v2 06/30] mm: change thp_order and thp_nr as we will have not just PMD THPs Zi Yan
2020-09-28 17:54 ` [RFC PATCH v2 07/30] mm: thp: add anonymous PUD THP page fault support without enabling it Zi Yan
2020-09-28 17:54 ` [RFC PATCH v2 08/30] mm: thp: add PUD THP support for copy_huge_pud Zi Yan
2020-09-28 17:54 ` [RFC PATCH v2 09/30] mm: thp: add PUD THP support to zap_huge_pud Zi Yan
2020-09-28 17:54 ` [RFC PATCH v2 10/30] fs: proc: add PUD THP kpageflag Zi Yan
2020-09-28 17:54 ` [RFC PATCH v2 11/30] mm: thp: handling PUD THP reference bit Zi Yan
2020-09-28 17:54 ` [RFC PATCH v2 12/30] mm: rmap: add mappped/unmapped page order to anonymous page rmap functions Zi Yan
2020-09-28 17:54 ` [RFC PATCH v2 13/30] mm: rmap: add map_order to page_remove_anon_compound_rmap Zi Yan
2020-09-28 17:54 ` [RFC PATCH v2 14/30] mm: thp: add PUD THP split_huge_pud_page() function Zi Yan
2020-09-28 17:54 ` [RFC PATCH v2 15/30] mm: thp: add PUD THP to deferred split list when PUD mapping is gone Zi Yan
2020-09-28 17:54 ` [RFC PATCH v2 16/30] mm: debug: adapt dump_page to PUD THP Zi Yan
2020-09-28 17:54 ` [RFC PATCH v2 17/30] mm: thp: PUD THP COW splits PUD page and falls back to PMD page Zi Yan
2020-09-28 17:54 ` [RFC PATCH v2 18/30] mm: thp: PUD THP follow_p*d_page() support Zi Yan
2020-09-28 17:54 ` [RFC PATCH v2 19/30] mm: stats: make smap stats understand PUD THPs Zi Yan
2020-09-28 17:54 ` [RFC PATCH v2 20/30] mm: page_vma_walk: teach it about PMD-mapped PUD THP Zi Yan
2020-09-28 17:54 ` [RFC PATCH v2 21/30] mm: thp: PUD THP support in try_to_unmap() Zi Yan
2020-09-28 17:54 ` [RFC PATCH v2 22/30] mm: thp: split PUD THPs at page reclaim Zi Yan
2020-09-28 17:54 ` [RFC PATCH v2 23/30] mm: support PUD THP pagemap support Zi Yan
2020-09-28 17:54 ` [RFC PATCH v2 24/30] mm: madvise: add page size options to MADV_HUGEPAGE and MADV_NOHUGEPAGE Zi Yan
2020-09-28 17:54 ` [RFC PATCH v2 25/30] mm: vma: add VM_HUGEPAGE_PUD to vm_flags at bit 37 Zi Yan
2020-09-28 17:54 ` [RFC PATCH v2 26/30] mm: thp: add a global knob to enable/disable PUD THPs Zi Yan
2020-09-28 17:54 ` [RFC PATCH v2 27/30] mm: thp: make PUD THP size public Zi Yan
2020-09-28 17:54 ` [RFC PATCH v2 28/30] hugetlb: cma: move cma reserve function to cma.c Zi Yan
2020-09-28 17:54 ` [RFC PATCH v2 29/30] mm: thp: use cma reservation for pud thp allocation Zi Yan
2020-09-28 17:54 ` [RFC PATCH v2 30/30] mm: thp: enable anonymous PUD THP at page fault path Zi Yan
2020-09-30 11:55 ` Michal Hocko [this message]
2020-10-01 15:14 ` [RFC PATCH v2 00/30] 1GB PUD THP support on x86_64 Zi Yan
2020-10-02 7:32 ` Michal Hocko
2020-10-02 7:50 ` David Hildenbrand
2020-10-02 8:10 ` Michal Hocko
2020-10-02 8:30 ` David Hildenbrand
2020-10-05 15:03 ` Zi Yan
2020-10-05 15:55 ` Matthew Wilcox
2020-10-05 17:04 ` Roman Gushchin
2020-10-05 19:12 ` Zi Yan
2020-10-05 19:37 ` Matthew Wilcox
2020-10-05 17:16 ` Roman Gushchin
2020-10-05 17:27 ` David Hildenbrand
2020-10-05 18:25 ` Roman Gushchin
2020-10-05 18:33 ` David Hildenbrand
2020-10-05 19:11 ` Roman Gushchin
2020-10-06 8:25 ` David Hildenbrand
2020-10-05 17:39 ` David Hildenbrand
2020-10-05 18:05 ` Zi Yan
2020-10-05 18:48 ` David Hildenbrand
2020-10-06 11:59 ` Michal Hocko
2020-10-05 15:34 ` Zi Yan
2020-10-05 17:30 ` David Hildenbrand
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