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Message-ID: <3987659f-2adc-477b-b507-ead2f10c1849@redhat.com>
Date: Wed, 20 Mar 2024 15:09:15 +0100
From: David Hildenbrand <david@...hat.com>
To: Ryan Roberts <ryan.roberts@....com>,
Andrew Morton <akpm@...ux-foundation.org>,
Matthew Wilcox <willy@...radead.org>, Huang Ying <ying.huang@...el.com>,
Gao Xiang <xiang@...nel.org>, Yu Zhao <yuzhao@...gle.com>,
Yang Shi <shy828301@...il.com>, Michal Hocko <mhocko@...e.com>,
Kefeng Wang <wangkefeng.wang@...wei.com>, Barry Song <21cnbao@...il.com>,
Chris Li <chrisl@...nel.org>
Cc: linux-mm@...ck.org, linux-kernel@...r.kernel.org
Subject: Re: [PATCH v4 6/6] mm: madvise: Avoid split during MADV_PAGEOUT and
MADV_COLD
On 20.03.24 14:57, Ryan Roberts wrote:
> On 15/03/2024 10:35, David Hildenbrand wrote:
>>> - if (!pageout && pte_young(ptent)) {
>>> - ptent = ptep_get_and_clear_full(mm, addr, pte,
>>> - tlb->fullmm);
>>> - ptent = pte_mkold(ptent);
>>> - set_pte_at(mm, addr, pte, ptent);
>>> - tlb_remove_tlb_entry(tlb, pte, addr);
>>> + if (!pageout) {
>>> + for (; nr != 0; nr--, pte++, addr += PAGE_SIZE) {
>>> + if (ptep_test_and_clear_young(vma, addr, pte))
>>> + tlb_remove_tlb_entry(tlb, pte, addr);
>>> + }
>>> }
>>
>>
>> The following might turn out a bit nicer: Make folio_pte_batch() collect
>> "any_young", then doing something like we do with "any_writable" in the fork()
>> case:
>>
>> ...
>> nr = folio_pte_batch(folio, addr, pte, ptent, max_nr,
>> fpb_flags, NULL, any_young);
>> if (any_young)
>> pte_mkyoung(ptent)
>> ...
>>
>> if (!pageout && pte_young(ptent)) {
>> mkold_full_ptes(mm, addr, pte, nr, tlb->fullmm);
>
> I don't think tlb->fullmm makes sense here because we are not clearing the pte,
> so there is no chance of optimization? So planning to call this mkold_ptes() and
> remove that param. Have I missed something?
Agreed.
--
Cheers,
David / dhildenb
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