From: Yin Fengwei <fengwei.yin@intel.com>
To: Will Deacon <will@kernel.org>, Matthew Wilcox <willy@infradead.org>
Cc: Ryan Roberts <ryan.roberts@arm.com>, <linux-arch@vger.kernel.org>,
<linux-mm@kvack.org>, <linux-kernel@vger.kernel.org>
Subject: Re: [PATCH v4 35/36] mm: Convert do_set_pte() to set_pte_range()
Date: Mon, 27 Mar 2023 09:23:04 +0800 [thread overview]
Message-ID: <240650f1-a5cd-8b0c-fe91-0f8b116d6fe9@intel.com> (raw)
In-Reply-To: <20230324172319.GA27842@willie-the-truck>
On 3/25/23 01:23, Will Deacon wrote:
> On Fri, Mar 24, 2023 at 03:11:00PM +0000, Matthew Wilcox wrote:
>> On Fri, Mar 24, 2023 at 02:58:29PM +0000, Will Deacon wrote:
>>> Yes, please don't fault everything in as young as it has caused horrible
>>> vmscan behaviour leading to app-startup slowdown in the past:
>>>
>>> https://lore.kernel.org/all/20210111140149.GB7642@willie-the-truck/
>>>
>>> If we have to use the same value for all the ptes, then just base them
>>> all on arch_wants_old_prefaulted_pte() as iirc hardware AF was pretty
>>> cheap in practice for us.
>>
>> I think that's wrong, because this is a different scenario.
>>
>> Before:
>>
>> We faulted in N single-page folios. Each page/folio is tracked
>> independently. That's N entries on whatever LRU list it ends up on.
>> The prefaulted ones _should_ be marked old -- they haven't been
>> accessed; we've just decided to put them in the page tables to
>> speed up faultaround. The unaccessed pages need to fall off the LRU
>> list as quickly as possible; keeping them around only hurts if the
>> workload has no locality of reference.
>>
>> After:
>>
>> We fault in N folios, some possibly consisting of multiple pages.
>> Each folio is tracked separately, but individual pages in the folio
>> are not tracked; they belong to their folio. In this scenario, if
>> the other PTEs for pages in the same folio are marked as young or old
>> doesn't matter; the entire folio will be tracked as young, because we
>> referenced one of the pages in this folio. Marking the other PTEs as
>> young actually helps because we don't take pagefaults on them (whether
>> we have a HW or SW accessed bit).
>>
>> (can i just say that i dislike how we mix up our old/young accessed/not
>> terminology here?)
>>
>> We should still mark the PTEs referencing unaccessed folios as old.
>> No argument there, and this patch does that. But it's fine for all the
>> PTEs referencing the accessed folio to have the young bit, at least as
>> far as I can tell.
>
> Ok, thanks for the explanation. So as long as
> arch_wants_old_prefaulted_pte() is taken into account for the unaccessed
> folios, then I think we should be good? Unconditionally marking those
> PTEs as old probably hurts x86.
Yes. We do only mark PTEs old for arch_wants_old_prefaulted_pte()
system. Thanks.
Regards
Yin, Fengwei
>
> Will
next prev parent reply other threads:[~2023-03-27 1:27 UTC|newest]
Thread overview: 138+ messages / expand[flat|nested] mbox.gz Atom feed top
2023-03-15 5:14 [PATCH v4 00/36] New page table range API Matthew Wilcox (Oracle)
2023-03-15 5:14 ` [PATCH v4 01/36] mm: Convert page_table_check_pte_set() to page_table_check_ptes_set() Matthew Wilcox (Oracle)
2023-03-15 9:21 ` Mike Rapoport
2023-03-23 18:36 ` Pasha Tatashin
2023-05-25 2:16 ` Anshuman Khandual
2023-03-15 5:14 ` [PATCH v4 02/36] mm: Add generic flush_icache_pages() and documentation Matthew Wilcox (Oracle)
2023-03-15 9:27 ` Mike Rapoport
2023-05-25 2:23 ` Anshuman Khandual
2023-03-15 5:14 ` [PATCH v4 03/36] mm: Add folio_flush_mapping() Matthew Wilcox (Oracle)
2023-03-15 9:28 ` Mike Rapoport
2023-05-25 2:35 ` Anshuman Khandual
2023-03-15 5:14 ` [PATCH v4 04/36] mm: Remove ARCH_IMPLEMENTS_FLUSH_DCACHE_FOLIO Matthew Wilcox (Oracle)
2023-03-15 9:28 ` Mike Rapoport
2023-05-25 2:43 ` Anshuman Khandual
2023-03-15 5:14 ` [PATCH v4 05/36] mm: Add default definition of set_ptes() Matthew Wilcox (Oracle)
2023-03-15 9:34 ` Mike Rapoport
2023-05-25 3:01 ` Anshuman Khandual
2023-05-25 4:06 ` Matthew Wilcox
2023-03-15 5:14 ` [PATCH v4 06/36] alpha: Implement the new page table range API Matthew Wilcox (Oracle)
2023-03-15 9:41 ` Mike Rapoport
2023-03-15 5:14 ` [PATCH v4 07/36] arc: " Matthew Wilcox (Oracle)
2023-03-15 9:44 ` Mike Rapoport
2023-03-15 5:14 ` [PATCH v4 08/36] arm: " Matthew Wilcox (Oracle)
2023-03-15 9:48 ` Mike Rapoport
2023-03-15 10:56 ` Russell King (Oracle)
2023-03-15 5:14 ` [PATCH v4 09/36] arm64: " Matthew Wilcox (Oracle)
2023-03-15 9:49 ` Mike Rapoport
2023-05-25 3:35 ` Anshuman Khandual
2023-05-25 4:05 ` Matthew Wilcox
2023-05-25 4:43 ` Anshuman Khandual
2023-03-15 5:14 ` [PATCH v4 10/36] csky: " Matthew Wilcox (Oracle)
2023-03-15 9:50 ` Mike Rapoport
2023-03-15 5:14 ` [PATCH v4 11/36] hexagon: " Matthew Wilcox (Oracle)
2023-03-15 9:54 ` Mike Rapoport
2023-03-15 5:14 ` [PATCH v4 12/36] ia64: " Matthew Wilcox (Oracle)
2023-03-15 9:55 ` Mike Rapoport
2023-03-15 5:14 ` [PATCH v4 13/36] loongarch: " Matthew Wilcox (Oracle)
2023-03-15 10:07 ` Mike Rapoport
2023-03-15 5:14 ` [PATCH v4 14/36] m68k: " Matthew Wilcox (Oracle)
2023-03-15 7:43 ` Geert Uytterhoeven
2023-03-16 16:32 ` Geert Uytterhoeven
2023-03-15 10:07 ` Mike Rapoport
2023-03-15 5:14 ` [PATCH v4 15/36] microblaze: " Matthew Wilcox (Oracle)
2023-03-15 10:07 ` Mike Rapoport
2023-03-15 5:14 ` [PATCH v4 16/36] mips: " Matthew Wilcox (Oracle)
2023-03-15 10:08 ` Mike Rapoport
2023-03-15 10:50 ` Thomas Bogendoerfer
2023-03-15 20:33 ` Matthew Wilcox
2023-03-17 15:29 ` Thomas Bogendoerfer
2023-03-19 18:45 ` Thomas Bogendoerfer
2023-03-19 20:16 ` Matthew Wilcox
2023-03-21 11:30 ` Thomas Bogendoerfer
2023-03-15 5:14 ` [PATCH v4 17/36] nios2: " Matthew Wilcox (Oracle)
2023-03-15 10:08 ` Mike Rapoport
2023-06-13 22:45 ` Dinh Nguyen
2023-07-10 20:18 ` Matthew Wilcox
2023-07-10 23:10 ` Dinh Nguyen
2023-03-15 5:14 ` [PATCH v4 18/36] openrisc: " Matthew Wilcox (Oracle)
2023-03-15 10:09 ` Mike Rapoport
2023-03-15 5:14 ` [PATCH v4 19/36] parisc: " Matthew Wilcox (Oracle)
2023-03-15 10:09 ` Mike Rapoport
2023-03-15 5:14 ` [PATCH v4 20/36] powerpc: " Matthew Wilcox (Oracle)
2023-03-15 9:43 ` Christophe Leroy
2023-03-15 10:18 ` Christophe Leroy
2023-03-17 3:47 ` Matthew Wilcox
2023-03-18 9:19 ` Christophe Leroy
2023-07-10 20:24 ` Matthew Wilcox
2023-07-11 4:40 ` Christophe Leroy
2023-03-15 10:09 ` Mike Rapoport
2023-03-15 5:14 ` [PATCH v4 21/36] riscv: " Matthew Wilcox (Oracle)
2023-03-15 10:10 ` Mike Rapoport
2023-03-15 5:14 ` [PATCH v4 22/36] s390: " Matthew Wilcox (Oracle)
2023-03-15 10:10 ` Mike Rapoport
2023-03-15 5:14 ` [PATCH v4 23/36] superh: " Matthew Wilcox (Oracle)
2023-03-15 7:22 ` John Paul Adrian Glaubitz
2023-03-15 7:36 ` John Paul Adrian Glaubitz
2023-03-15 10:10 ` Mike Rapoport
2023-03-15 5:14 ` [PATCH v4 24/36] sparc32: " Matthew Wilcox (Oracle)
2023-03-15 10:11 ` Mike Rapoport
2023-03-15 5:14 ` [PATCH v4 25/36] sparc64: " Matthew Wilcox (Oracle)
2023-03-15 10:11 ` Mike Rapoport
2023-03-15 5:14 ` [PATCH v4 26/36] um: " Matthew Wilcox (Oracle)
2023-03-15 10:12 ` Mike Rapoport
2023-03-15 5:14 ` [PATCH v4 27/36] x86: " Matthew Wilcox (Oracle)
2023-03-15 10:12 ` Mike Rapoport
2023-03-15 10:34 ` Peter Zijlstra
2023-03-15 11:16 ` Mike Rapoport
2023-03-15 11:19 ` Peter Zijlstra
2023-03-15 16:12 ` Matthew Wilcox
2023-03-15 5:14 ` [PATCH v4 28/36] xtensa: " Matthew Wilcox (Oracle)
2023-03-15 10:12 ` Mike Rapoport
2023-03-15 5:14 ` [PATCH v4 29/36] mm: Remove page_mapping_file() Matthew Wilcox (Oracle)
2023-05-25 3:50 ` Anshuman Khandual
2023-05-25 4:03 ` Matthew Wilcox
2023-05-25 4:46 ` Anshuman Khandual
2023-05-25 5:37 ` Anshuman Khandual
2023-03-15 5:14 ` [PATCH v4 30/36] mm: Rationalise flush_icache_pages() and flush_icache_page() Matthew Wilcox (Oracle)
2023-03-15 5:14 ` [PATCH v4 31/36] mm: Tidy up set_ptes definition Matthew Wilcox (Oracle)
2023-05-25 6:20 ` Anshuman Khandual
2023-03-15 5:14 ` [PATCH v4 32/36] mm: Use flush_icache_pages() in do_set_pmd() Matthew Wilcox (Oracle)
2023-05-25 6:31 ` Anshuman Khandual
2023-03-15 5:14 ` [PATCH v4 33/36] filemap: Add filemap_map_folio_range() Matthew Wilcox (Oracle)
2023-03-15 5:14 ` [PATCH v4 34/36] rmap: add folio_add_file_rmap_range() Matthew Wilcox (Oracle)
2023-03-15 13:34 ` Ryan Roberts
2023-03-15 16:08 ` Ryan Roberts
2023-03-16 16:27 ` Yin, Fengwei
2023-03-16 16:34 ` Ryan Roberts
2023-03-17 8:23 ` Yin, Fengwei
2023-03-17 12:46 ` Ryan Roberts
2023-03-17 13:28 ` Yin, Fengwei
2023-03-15 5:14 ` [PATCH v4 35/36] mm: Convert do_set_pte() to set_pte_range() Matthew Wilcox (Oracle)
2023-03-15 15:26 ` Ryan Roberts
2023-03-16 16:23 ` Yin, Fengwei
2023-03-16 16:38 ` Ryan Roberts
2023-03-16 16:41 ` Yin, Fengwei
2023-03-16 16:50 ` Ryan Roberts
2023-03-16 17:52 ` Matthew Wilcox
2023-03-17 1:58 ` Yin, Fengwei
2023-03-17 3:44 ` Matthew Wilcox
2023-03-17 6:33 ` Yin, Fengwei
2023-03-17 8:00 ` Ryan Roberts
2023-03-17 8:19 ` Yin, Fengwei
2023-03-17 13:00 ` Ryan Roberts
2023-03-17 13:44 ` Yin, Fengwei
2023-03-24 14:58 ` Will Deacon
2023-03-24 15:11 ` Matthew Wilcox
2023-03-24 17:23 ` Will Deacon
2023-03-27 1:23 ` Yin Fengwei [this message]
2023-03-20 13:38 ` Yin, Fengwei
2023-03-20 14:08 ` Matthew Wilcox
2023-03-21 1:58 ` Yin, Fengwei
2023-03-21 5:13 ` Yin Fengwei
2023-05-30 8:07 ` [PATCH 0/4] New page table range API fixup patches Yin Fengwei
2023-05-30 8:07 ` [PATCH 1/4] filemap: avoid interfere with xas.xa_index Yin Fengwei
2023-05-30 8:07 ` [PATCH 2/4] rmap: fix typo in folio_add_file_rmap_range() Yin Fengwei
2023-05-30 8:07 ` [PATCH 3/4] mm: mark PTEs referencing the accessed folio young Yin Fengwei
2023-05-30 8:07 ` [PATCH 4/4] filemap: Check address range in filemap_map_folio_range() Yin Fengwei
2023-03-15 5:14 ` [PATCH v4 36/36] filemap: Batch PTE mappings Matthew Wilcox (Oracle)
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