From: Nadav Amit <nadav.amit@gmail.com>
To: David Hildenbrand <david@redhat.com>
Cc: Linux Kernel Mailing List <linux-kernel@vger.kernel.org>,
linux-mm <linux-mm@kvack.org>,
Andrew Morton <akpm@linux-foundation.org>,
Linus Torvalds <torvalds@linux-foundation.org>,
Ryan Roberts <ryan.roberts@arm.com>,
Matthew Wilcox <willy@infradead.org>,
Hugh Dickins <hughd@google.com>,
Yin Fengwei <fengwei.yin@intel.com>,
Yang Shi <shy828301@gmail.com>, Ying Huang <ying.huang@intel.com>,
Zi Yan <ziy@nvidia.com>, Peter Zijlstra <peterz@infradead.org>,
Ingo Molnar <mingo@redhat.com>, Will Deacon <will@kernel.org>,
Waiman Long <longman@redhat.com>,
"Paul E. McKenney" <paulmck@kernel.org>
Subject: Re: [PATCH WIP v1 07/20] mm/rmap_id: track if one ore multiple MMs map a partially-mappable folio
Date: Mon, 18 Dec 2023 16:34:42 +0200 [thread overview]
Message-ID: <4FFED5A1-BF86-480D-8CB7-BECE5C413B44@gmail.com> (raw)
In-Reply-To: <944d990f-3c98-4ade-8176-4e4b25eae0b8@redhat.com>
> On Dec 18, 2023, at 4:04 PM, David Hildenbrand <david@redhat.com> wrote:
>
> But adding 1 "0" bit is not sufficient for handling order-2 folios (P = 4), only for handling order-1 folios. So what the current approach does is the following (P = 4):
>
> RMAP-ID | | Subid |
> -----------------------------------
> 0 | 0000 | 0 | 0000 0000
> 1 | 0001 | 1 | 0000 0001
> 2 | 0010 | 5 | 0000 0101
> 3 | 0011 | 6 | 0000 0110
> 4 | 0100 | 25 | 0001 1001
> 5 | 0101 | 26 | 0001 1010
> 6 | 0110 | 30 | 0001 1110
> 7 | 0111 | 31 | 0001 1111
> 8 | 1000 | 125 | 0111 1101
> 9 | 1001 | 126 | 0111 1110
> 10 | 1010 | 130 | 1000 0010
> 11 | 1011 | 131 | 1000 0011
> 12 | 1100 | 150 | 1001 0110
> 13 | 1101 | 151 | 1001 0111
> 14 | 1110 | 155 | 1001 1011
> 15 | 1111 | 156 | 1001 1100
Yes, of course. Silly me. You want to take advantage of the counter not
saturating for orders K where K-1 is not a power of 2.
I get your point. Not sure whether it worth the complexity though…
next prev parent reply other threads:[~2023-12-18 14:34 UTC|newest]
Thread overview: 26+ messages / expand[flat|nested] mbox.gz Atom feed top
2023-11-24 13:26 [PATCH WIP v1 00/20] mm: precise "mapped shared" vs. "mapped exclusively" detection for PTE-mapped THP / partially-mappable folios David Hildenbrand
2023-11-24 13:26 ` [PATCH WIP v1 01/20] mm/rmap: factor out adding folio range into __folio_add_rmap_range() David Hildenbrand
2023-11-24 13:26 ` [PATCH WIP v1 02/20] mm: add a total mapcount for large folios David Hildenbrand
2023-11-24 13:26 ` [PATCH WIP v1 03/20] mm: convert folio_estimated_sharers() to folio_mapped_shared() and improve it David Hildenbrand
2023-11-24 13:26 ` [PATCH WIP v1 04/20] mm/rmap: pass dst_vma to page_try_dup_anon_rmap() and page_dup_file_rmap() David Hildenbrand
2023-11-24 13:26 ` [PATCH WIP v1 05/20] mm/rmap: abstract total mapcount operations for partially-mappable folios David Hildenbrand
2023-11-24 13:26 ` [PATCH WIP v1 06/20] atomic_seqcount: new (raw) seqcount variant to support concurrent writers David Hildenbrand
2023-11-24 13:26 ` [PATCH WIP v1 07/20] mm/rmap_id: track if one ore multiple MMs map a partially-mappable folio David Hildenbrand
2023-12-17 19:13 ` Nadav Amit
2023-12-18 14:04 ` David Hildenbrand
2023-12-18 14:34 ` Nadav Amit [this message]
2023-11-24 13:26 ` [PATCH WIP v1 08/20] mm: pass MM to folio_mapped_shared() David Hildenbrand
2023-11-24 13:26 ` [PATCH WIP v1 09/20] mm: improve folio_mapped_shared() for partially-mappable folios using rmap IDs David Hildenbrand
2023-11-24 13:26 ` [PATCH WIP v1 10/20] mm/memory: COW reuse support for PTE-mapped THP with " David Hildenbrand
2023-11-24 13:26 ` [PATCH WIP v1 11/20] mm/rmap_id: support for 1, 2 and 3 values by manual calculation David Hildenbrand
2023-11-24 13:26 ` [PATCH WIP v1 12/20] mm/rmap: introduce folio_add_anon_rmap_range() David Hildenbrand
2023-11-24 13:26 ` [PATCH WIP v1 13/20] mm/huge_memory: batch rmap operations in __split_huge_pmd_locked() David Hildenbrand
2023-11-24 13:26 ` [PATCH WIP v1 14/20] mm/huge_memory: avoid folio_refcount() < folio_mapcount() " David Hildenbrand
2023-11-24 13:26 ` [PATCH WIP v1 15/20] mm/rmap_id: verify precalculated subids with CONFIG_DEBUG_VM David Hildenbrand
2023-11-24 13:26 ` [PATCH WIP v1 16/20] atomic_seqcount: support a single exclusive writer in the absence of other writers David Hildenbrand
2023-11-24 13:26 ` [PATCH WIP v1 17/20] mm/rmap_id: reduce atomic RMW operations when we are the exclusive writer David Hildenbrand
2023-11-24 13:26 ` [PATCH WIP v1 18/20] atomic_seqcount: use atomic add-return instead of atomic cmpxchg on 64bit David Hildenbrand
2023-11-24 13:26 ` [PATCH WIP v1 19/20] mm/rmap: factor out removing folio range into __folio_remove_rmap_range() David Hildenbrand
2023-11-24 13:26 ` [PATCH WIP v1 20/20] mm/rmap: perform all mapcount operations of large folios under the rmap seqcount David Hildenbrand
2023-11-24 20:55 ` [PATCH WIP v1 00/20] mm: precise "mapped shared" vs. "mapped exclusively" detection for PTE-mapped THP / partially-mappable folios Linus Torvalds
2023-11-25 17:02 ` David Hildenbrand
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