From: Mike Kravetz <mike.kravetz@oracle.com>
To: "Dr. David Alan Gilbert" <dgilbert@redhat.com>
Cc: James Houghton <jthoughton@google.com>,
Muchun Song <songmuchun@bytedance.com>,
Peter Xu <peterx@redhat.com>,
David Hildenbrand <david@redhat.com>,
David Rientjes <rientjes@google.com>,
Axel Rasmussen <axelrasmussen@google.com>,
Mina Almasry <almasrymina@google.com>, Jue Wang <juew@google.com>,
Manish Mishra <manish.mishra@nutanix.com>,
linux-mm@kvack.org, linux-kernel@vger.kernel.org
Subject: Re: [RFC PATCH 07/26] hugetlb: add hugetlb_pte to track HugeTLB page table entries
Date: Tue, 12 Jul 2022 10:51:06 -0700 [thread overview]
Message-ID: <Ys20iusvF1An6BLs@monkey> (raw)
In-Reply-To: <Ys1B+fXo2uSPd46B@work-vm>
On 07/12/22 10:42, Dr. David Alan Gilbert wrote:
> * Mike Kravetz (mike.kravetz@oracle.com) wrote:
> > On 06/24/22 17:36, James Houghton wrote:
> > > After high-granularity mapping, page table entries for HugeTLB pages can
> > > be of any size/type. (For example, we can have a 1G page mapped with a
> > > mix of PMDs and PTEs.) This struct is to help keep track of a HugeTLB
> > > PTE after we have done a page table walk.
> >
> > This has been rolling around in my head.
> >
> > Will this first use case (live migration) actually make use of this
> > 'mixed mapping' model where hugetlb pages could be mapped at the PUD,
> > PMD and PTE level all within the same vma? I only understand the use
> > case from a high level. But, it seems that we would want to only want
> > to migrate PTE (or PMD) sized pages and not necessarily a mix.
>
> I suspect we would pick one size and use that size for all transfers
> when in postcopy; not sure if there are any side cases though.
>
> > The only reason I ask is because the code might be much simpler if all
> > mappings within a vma were of the same size. Of course, the
> > performance/latency of converting a large mapping may be prohibitively
> > expensive.
>
> Imagine we're migrating a few TB VM, backed by 1GB hugepages, I'm guessing it
> would be nice to clean up the PTE/PMDs for split 1GB pages as they're
> completed rather than having thousands of them for the whole VM.
> (I'm not sure if that is already doable)
Seems that would be doable by calling MADV_COLLAPSE for 1GB pages as
they are completed.
Thanks for information on post copy.
--
Mike Kravetz
next prev parent reply other threads:[~2022-07-12 17:51 UTC|newest]
Thread overview: 123+ messages / expand[flat|nested] mbox.gz Atom feed top
2022-06-24 17:36 [RFC PATCH 00/26] hugetlb: Introduce HugeTLB high-granularity mapping James Houghton
2022-06-24 17:36 ` [RFC PATCH 01/26] hugetlb: make hstate accessor functions const James Houghton
2022-06-24 18:43 ` Mina Almasry
[not found] ` <e55f90f5-ba14-5d6e-8f8f-abf731b9095e@nutanix.com>
[not found] ` <bb903be9-546d-04a7-e9e4-f5ba313319de@nutanix.com>
2022-06-28 17:08 ` James Houghton
2022-06-29 6:18 ` Muchun Song
2022-06-24 17:36 ` [RFC PATCH 02/26] hugetlb: sort hstates in hugetlb_init_hstates James Houghton
2022-06-24 18:51 ` Mina Almasry
2022-06-27 12:08 ` manish.mishra
2022-06-28 15:35 ` James Houghton
2022-06-27 18:42 ` Mike Kravetz
2022-06-28 15:40 ` James Houghton
2022-06-29 6:39 ` Muchun Song
2022-06-29 21:06 ` Mike Kravetz
2022-06-29 21:13 ` James Houghton
2022-06-24 17:36 ` [RFC PATCH 03/26] hugetlb: add make_huge_pte_with_shift James Houghton
2022-06-24 19:01 ` Mina Almasry
2022-06-27 12:13 ` manish.mishra
2022-06-24 17:36 ` [RFC PATCH 04/26] hugetlb: make huge_pte_lockptr take an explicit shift argument James Houghton
2022-06-27 12:26 ` manish.mishra
2022-06-27 20:51 ` Mike Kravetz
2022-06-28 15:29 ` James Houghton
2022-06-29 6:09 ` Muchun Song
2022-06-29 21:03 ` Mike Kravetz
2022-06-29 21:39 ` James Houghton
2022-06-29 22:24 ` Mike Kravetz
2022-06-30 9:35 ` Muchun Song
2022-06-30 16:23 ` James Houghton
2022-06-30 17:40 ` Mike Kravetz
2022-07-01 3:32 ` Muchun Song
2022-06-24 17:36 ` [RFC PATCH 05/26] hugetlb: add CONFIG_HUGETLB_HIGH_GRANULARITY_MAPPING James Houghton
2022-06-27 12:28 ` manish.mishra
2022-06-28 20:03 ` Mina Almasry
2022-06-24 17:36 ` [RFC PATCH 06/26] mm: make free_p?d_range functions public James Houghton
2022-06-27 12:31 ` manish.mishra
2022-06-28 20:35 ` Mike Kravetz
2022-07-12 20:52 ` James Houghton
2022-06-24 17:36 ` [RFC PATCH 07/26] hugetlb: add hugetlb_pte to track HugeTLB page table entries James Houghton
2022-06-27 12:47 ` manish.mishra
2022-06-29 16:28 ` James Houghton
2022-06-28 20:25 ` Mina Almasry
2022-06-29 16:42 ` James Houghton
2022-06-28 20:44 ` Mike Kravetz
2022-06-29 16:24 ` James Houghton
2022-07-11 23:32 ` Mike Kravetz
2022-07-12 9:42 ` Dr. David Alan Gilbert
2022-07-12 17:51 ` Mike Kravetz [this message]
2022-07-15 16:35 ` Peter Xu
2022-07-15 21:52 ` Axel Rasmussen
2022-07-15 23:03 ` Peter Xu
2022-09-08 17:38 ` Peter Xu
2022-09-08 17:54 ` James Houghton
2022-06-24 17:36 ` [RFC PATCH 08/26] hugetlb: add hugetlb_free_range to free PT structures James Houghton
2022-06-27 12:52 ` manish.mishra
2022-06-28 20:27 ` Mina Almasry
2022-06-24 17:36 ` [RFC PATCH 09/26] hugetlb: add hugetlb_hgm_enabled James Houghton
2022-06-28 20:33 ` Mina Almasry
2022-09-08 18:07 ` Peter Xu
2022-09-08 18:13 ` James Houghton
2022-06-24 17:36 ` [RFC PATCH 10/26] hugetlb: add for_each_hgm_shift James Houghton
2022-06-27 13:01 ` manish.mishra
2022-06-28 21:58 ` Mina Almasry
2022-07-07 21:39 ` Mike Kravetz
2022-07-08 15:52 ` James Houghton
2022-07-09 21:55 ` Mina Almasry
2022-06-24 17:36 ` [RFC PATCH 11/26] hugetlb: add hugetlb_walk_to to do PT walks James Houghton
2022-06-27 13:07 ` manish.mishra
2022-07-07 23:03 ` Mike Kravetz
2022-09-08 18:20 ` Peter Xu
2022-06-24 17:36 ` [RFC PATCH 12/26] hugetlb: add HugeTLB splitting functionality James Houghton
2022-06-27 13:50 ` manish.mishra
2022-06-29 16:10 ` James Houghton
2022-06-29 14:33 ` manish.mishra
2022-06-29 16:20 ` James Houghton
2022-06-24 17:36 ` [RFC PATCH 13/26] hugetlb: add huge_pte_alloc_high_granularity James Houghton
2022-06-29 14:11 ` manish.mishra
2022-06-24 17:36 ` [RFC PATCH 14/26] hugetlb: add HGM support for hugetlb_fault and hugetlb_no_page James Houghton
2022-06-29 14:40 ` manish.mishra
2022-06-29 15:56 ` James Houghton
2022-06-24 17:36 ` [RFC PATCH 15/26] hugetlb: make unmapping compatible with high-granularity mappings James Houghton
2022-07-19 10:19 ` manish.mishra
2022-07-19 15:58 ` James Houghton
2022-06-24 17:36 ` [RFC PATCH 16/26] hugetlb: make hugetlb_change_protection compatible with HGM James Houghton
2022-06-24 17:36 ` [RFC PATCH 17/26] hugetlb: update follow_hugetlb_page to support HGM James Houghton
2022-07-19 10:48 ` manish.mishra
2022-07-19 16:19 ` James Houghton
2022-06-24 17:36 ` [RFC PATCH 18/26] hugetlb: use struct hugetlb_pte for walk_hugetlb_range James Houghton
2022-06-24 17:36 ` [RFC PATCH 19/26] hugetlb: add HGM support for copy_hugetlb_page_range James Houghton
2022-07-11 23:41 ` Mike Kravetz
2022-07-12 17:19 ` James Houghton
2022-07-12 18:06 ` Mike Kravetz
2022-07-15 21:39 ` Axel Rasmussen
2022-06-24 17:36 ` [RFC PATCH 20/26] hugetlb: add support for high-granularity UFFDIO_CONTINUE James Houghton
2022-07-15 16:21 ` Peter Xu
2022-07-15 16:58 ` James Houghton
2022-07-15 17:20 ` Peter Xu
2022-07-20 20:58 ` James Houghton
2022-07-21 19:09 ` Peter Xu
2022-07-21 19:44 ` James Houghton
2022-07-21 19:53 ` Peter Xu
2022-06-24 17:36 ` [RFC PATCH 21/26] hugetlb: add hugetlb_collapse James Houghton
2022-06-24 17:36 ` [RFC PATCH 22/26] madvise: add uapi for HugeTLB HGM collapse: MADV_COLLAPSE James Houghton
2022-06-24 17:36 ` [RFC PATCH 23/26] userfaultfd: add UFFD_FEATURE_MINOR_HUGETLBFS_HGM James Houghton
2022-06-24 17:36 ` [RFC PATCH 24/26] arm64/hugetlb: add support for high-granularity mappings James Houghton
2022-06-24 17:36 ` [RFC PATCH 25/26] selftests: add HugeTLB HGM to userfaultfd selftest James Houghton
2022-06-24 17:36 ` [RFC PATCH 26/26] selftests: add HugeTLB HGM to KVM demand paging selftest James Houghton
2022-06-24 18:29 ` [RFC PATCH 00/26] hugetlb: Introduce HugeTLB high-granularity mapping Matthew Wilcox
2022-06-27 16:36 ` James Houghton
2022-06-27 17:56 ` Dr. David Alan Gilbert
2022-06-27 20:31 ` James Houghton
2022-06-28 0:04 ` Nadav Amit
2022-06-30 19:21 ` Peter Xu
2022-07-01 5:54 ` Nadav Amit
2022-06-28 8:20 ` Dr. David Alan Gilbert
2022-06-30 16:09 ` Peter Xu
2022-06-24 18:41 ` Mina Almasry
2022-06-27 16:27 ` James Houghton
2022-06-28 14:17 ` Muchun Song
2022-06-28 17:26 ` Mina Almasry
2022-06-28 17:56 ` Dr. David Alan Gilbert
2022-06-29 18:31 ` James Houghton
2022-06-29 20:39 ` Axel Rasmussen
2022-06-24 18:47 ` Matthew Wilcox
2022-06-27 16:48 ` James Houghton
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