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charset=UTF-8; format=flowed Content-Transfer-Encoding: 8bit X-Rspam-User: X-Rspamd-Queue-Id: 010F5100007 X-Rspamd-Server: rspam04 X-Stat-Signature: dam3f6m73afbq6kagea5djgd9ayg36de X-HE-Tag: 1744718805-631101 X-HE-Meta: U2FsdGVkX1/zHs1SqG6eHpUnDbXZCJWzujW7GGHZ80FI2Iwy2NXXiJTSJPPGuV+j2rJ2F7FnPN3m1zVu47ckNpFLJ46ZlvxMnsBDkuOxozB7ncaO5W5J/GarVgq2JMg3TquMQlYuY3QFDb+XnhhzDiBDJtxoV+9ywWUrCes56Gzv+hM/NEsd4HQngs0ym8CuruU8HNO9cmYyjbLabl9FDerW4KEOFQzdYXt09BcOY0yT9VIY2Id9TA5T0rowsJAb+IMA3fW3LDH3rDanlfZGSvg0WcbViGz9XckqJyO18K4RLWlW1WTDOLF0v8R9OcA4HtirTUtVCJqWhS4o7wD0QJLKWdODZiRWIeI2DhzgQwLirGnr/WuKESMXcb/tJkzlbRPc887YBJONHg95kWV612VWaIKjALeaU/II2jBBhV3BuJQtWsQQEHomyJOLnnqD7aVu7MFmjVQ1WcJP/+pOG0W+nZd0pYTBGB6GeYThLSQOJXLMCrTvYLVnH12l2i9gC3YuiKu2jcL37kTjhir4hdUpCEZ13wa9/ybDMi/jIJUvRIePJMJ3pZvcO7AChQTLCOnCBK9eXIyqiJfBu0A2x9L6zE+uDxndtIQnSNba4ZBgIaxwNBEDaOMaJokCFxPgFLUwWwa1dU2REq5BduWnOHu7oKrTPP6ErbbsulZfygMrgtXvFieu93YVpyBS+hDofP4B/oBbODhVjDojEnJ1rtGNrbgm9RA/TCRKP0CbRnjHuXtPA9BegyaIqpX7kAyGzOPvcA5LDsqWTTfHqazibY+A5D6xG9/0kPG5XYARpCWyhFFy+rVZP/hjo2dDfpfRRDLzK796LtByVrVjiXpRKjXU3SWdjOfLoX5GYQ/oM/05mdJFIytXhXLL12st8MofmZiYtv5oWHozHsmXe2hsT/HGRCLcGnOl8hNm5ADYOohkuv2mm+j/s7mdCdtlwvYDLkCPWlgKrAoEjLlCTbE 1z1RM0Uo nisLlzSbesVTRp5pv1C0yGtDKk2Vpc5JVK86YWcvU3JhE4HPbNS9Io/0gG9jO98owLr6LYdhh27F9NU+sXL69j7qtELCofIBovye8NVFXj/JcCugkpjxwp5oS0O50kUW+w6G+zELe9H/874mn3Z1Gr/Z6YuJWYKY36tUnm9sKeHsdl9mM6b1eI40F6+4gKQs1PEmwgyK74fhFHPyXj8gXukiGEi0Wf3ZbrhQu32WdZ6jwPZvBdmBUADisiINYWrx6+sf4rLgC8tfy5C2hN+Tm6WhFJcb4iPa+KhdzEmdJr1y7Q5jZgf62zcc7fINKQMgjzgNhN4JfBlSR6aKp0PpAla31EQ9qxtlOL3gR X-Bogosity: Ham, tests=bogofilter, spamicity=0.000000, version=1.2.4 Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: List-Subscribe: List-Unsubscribe: On 15/04/25 5:29 pm, David Hildenbrand wrote: > On 15.04.25 13:47, Dev Jain wrote: >> >> >> On 15/04/25 3:47 pm, David Hildenbrand wrote: >>> On 11.04.25 10:13, Dev Jain wrote: >>>> After the check for queue_folio_required(), the code only cares >>>> about the >>>> folio in the for loop, i.e the PTEs are redundant. Therefore, optimize >>>> this >>>> loop by skipping over a PTE batch mapping the same folio. >>>> >>>> Signed-off-by: Dev Jain >>>> --- >>>> Unfortunately I have only build tested this since my test >>>> environment is >>>> broken. >>>> >>>>    mm/mempolicy.c | 12 +++++++++++- >>>>    1 file changed, 11 insertions(+), 1 deletion(-) >>>> >>>> diff --git a/mm/mempolicy.c b/mm/mempolicy.c >>>> index b28a1e6ae096..b019524da8a2 100644 >>>> --- a/mm/mempolicy.c >>>> +++ b/mm/mempolicy.c >>>> @@ -573,6 +573,9 @@ static int queue_folios_pte_range(pmd_t *pmd, >>>> unsigned long addr, >>>>        pte_t *pte, *mapped_pte; >>>>        pte_t ptent; >>>>        spinlock_t *ptl; >>>> +    int max_nr; >>>> +    const fpb_t fpb_flags = FPB_IGNORE_DIRTY | FPB_IGNORE_SOFT_DIRTY; >>>> +    int nr = 1; >>> >>> Try sticking to reverse xmas tree, please. (not completely the case >>> here, but fpb_flags can easily be moved all he way to the top) >> >> I thought that the initializations were to be kept at the bottom. > > Not that I am aware of. > >> Asking for future patches, should I put all declarations in reverse-xmas >> fashion (even those which I don't intend to touch w.r.t the patch >> logic), or do I do that for only my additions? > > We try to stay as close to reverse-xmas tree as possible. It's not > always possible (e.g., dependent assignments), but fpb_flags in this > case here can easily go all the way to the top. Sure. > > ... > >> >>> >>>   >       ptl = pmd_trans_huge_lock(pmd, vma);>       if (ptl) { >>>> @@ -586,7 +589,8 @@ static int queue_folios_pte_range(pmd_t *pmd, >>>> unsigned long addr, >>>>            walk->action = ACTION_AGAIN; >>>>            return 0; >>>>        } >>>   > -    for (; addr != end; pte++, addr += PAGE_SIZE) {> +    for (; >>> addr != end; pte += nr, addr += nr * PAGE_SIZE) { >>>> +        nr = 1; >>>>            ptent = ptep_get(pte); >>>>            if (pte_none(ptent)) >>>>                continue; >>>> @@ -607,6 +611,11 @@ static int queue_folios_pte_range(pmd_t *pmd, >>>> unsigned long addr, >>>>            if (!queue_folio_required(folio, qp)) >>>>                continue; >>>>            if (folio_test_large(folio)) { >>>> +            max_nr = (end - addr) >> PAGE_SHIFT; >>>> +            if (max_nr != 1) >>>> +                nr = folio_pte_batch(folio, addr, pte, ptent, >>>> +                             max_nr, fpb_flags, >>>> +                             NULL, NULL, NULL); >>> >>> We should probably do that immediately after we verified that >>> vm_normal_folio() have us something reasonable. >> >> But shouldn't we keep the small folio case separate to avoid the >> overhead of folio_pte_batch()? > > Yes, just do something like > > if (folio_test_large(folio) && end - addr > 1) >     nr = folio_pte_batch(folio, addr, pte, ptent, end - addr, >                  max_nr, fpb_flags, ...); > > before the folio_test_reserved(). > > Then you'd also skip the all ptes if !queue_folio_required. Ah got you, thanks. > >> >>> >>>>                /* >>>>                 * A large folio can only be isolated from LRU once, >>>>                 * but may be mapped by many PTEs (and Copy-On-Write may >>>> @@ -633,6 +642,7 @@ static int queue_folios_pte_range(pmd_t *pmd, >>>> unsigned long addr, >>>>                qp->nr_failed++; >>>>                if (strictly_unmovable(flags)) >>>>                    break; >>>> +            qp->nr_failed += nr - 1; >>> >>> Can't we do qp->nr_failed += nr; above? >> >> I did not dive deep into the significance of nr_failed, but I did that >> to keep the code, before and after the change, equivalent: > > And I question exactly that. > > If we hit strictly_unmovable(flags), we end up returning "-EIO" from > queue_folios_pte_range(). > > And staring at queue_pages_range(), we ignore nr_failed if > walk_page_range() returned an error. > > So looks like we can just add everything in one shot, independent of > strictly_unmovable()? Looks good to me this way. I'll change it, thanks. >