From: Ryan Roberts <ryan.roberts@arm.com>
To: David Hildenbrand <david@redhat.com>,
Barry Song <21cnbao@gmail.com>,
akpm@linux-foundation.org, linux-mm@kvack.org
Cc: baolin.wang@linux.alibaba.com, chrisl@kernel.org,
hanchuanhua@oppo.com, hannes@cmpxchg.org, hughd@google.com,
kasong@tencent.com, surenb@google.com, v-songbaohua@oppo.com,
willy@infradead.org, xiang@kernel.org, ying.huang@intel.com,
yosryahmed@google.com, yuzhao@google.com, ziy@nvidia.com,
linux-kernel@vger.kernel.org
Subject: Re: [PATCH v2 3/5] mm: swap_pte_batch: add an output argument to reture if all swap entries are exclusive
Date: Thu, 11 Apr 2024 16:36:16 +0100 [thread overview]
Message-ID: <ccbcbbb5-24eb-4503-ac7b-3171d39536e7@arm.com> (raw)
In-Reply-To: <a5a55919-46bc-4107-a0fc-14dc404e8c90@redhat.com>
On 11/04/2024 16:00, David Hildenbrand wrote:
> On 11.04.24 16:54, Ryan Roberts wrote:
>> On 09/04/2024 09:26, Barry Song wrote:
>>> From: Barry Song <v-songbaohua@oppo.com>
>>>
>>> Add a boolean argument named any_shared. If any of the swap entries are
>>> non-exclusive, set any_shared to true. The function do_swap_page() can
>>> then utilize this information to determine whether the entire large
>>> folio can be reused.
>>>
>>> Signed-off-by: Barry Song <v-songbaohua@oppo.com>
>>> ---
>>> mm/internal.h | 9 ++++++++-
>>> mm/madvise.c | 2 +-
>>> mm/memory.c | 2 +-
>>> 3 files changed, 10 insertions(+), 3 deletions(-)
>>>
>>> diff --git a/mm/internal.h b/mm/internal.h
>>> index 9d3250b4a08a..cae39c372bfc 100644
>>> --- a/mm/internal.h
>>> +++ b/mm/internal.h
>>> @@ -238,7 +238,8 @@ static inline pte_t pte_next_swp_offset(pte_t pte)
>>> *
>>> * Return: the number of table entries in the batch.
>>> */
>>> -static inline int swap_pte_batch(pte_t *start_ptep, int max_nr, pte_t pte)
>>> +static inline int swap_pte_batch(pte_t *start_ptep, int max_nr, pte_t pte,
>>> + bool *any_shared)
>>
>> Please update the docs in the comment above this for the new param; follow
>> folio_pte_batch()'s docs as a template.
>>
>>> {
>>> pte_t expected_pte = pte_next_swp_offset(pte);
>>> const pte_t *end_ptep = start_ptep + max_nr;
>>> @@ -248,12 +249,18 @@ static inline int swap_pte_batch(pte_t *start_ptep, int
>>> max_nr, pte_t pte)
>>> VM_WARN_ON(!is_swap_pte(pte));
>>> VM_WARN_ON(non_swap_entry(pte_to_swp_entry(pte)));
>>> + if (any_shared)
>>> + *any_shared |= !pte_swp_exclusive(pte);
>>
>> This is different from the approach in folio_pte_batch(). It inits *any_shared
>> to false and does NOT include the value of the first pte. I think that's odd,
>> personally and I prefer your approach. I'm not sure if there was a good reason
>> that David chose the other approach?
>
> Because in my case calling code does
>
> nr = folio_pte_batch(folio, addr, src_pte, pte, max_nr, flags,
> &any_writable);
>
> ...
>
> if (any_writable)
> pte = pte_mkwrite(pte, src_vma);
>
> ...
>
> and later checks in another function pte_write().
>
> So if the common pattern is that the original PTE will be used for checks, then
> it doesn't make sense to unnecessary checks+setting for the first PTE.
Yep understood. And I think adopting your semantics for any_shared actually
simplifies the code in patch 4 too; I've just commented that.
next prev parent reply other threads:[~2024-04-11 15:36 UTC|newest]
Thread overview: 54+ messages / expand[flat|nested] mbox.gz Atom feed top
2024-04-09 8:26 [PATCH v2 0/5] large folios swap-in: handle refault cases first Barry Song
2024-04-09 8:26 ` [PATCH v2 1/5] mm: swap: introduce swap_free_nr() for batched swap_free() Barry Song
2024-04-10 23:37 ` SeongJae Park
2024-04-11 1:27 ` Barry Song
2024-04-11 14:30 ` Ryan Roberts
2024-04-12 2:07 ` Chuanhua Han
2024-04-12 11:28 ` Ryan Roberts
2024-04-12 11:38 ` Chuanhua Han
2024-04-15 6:17 ` Huang, Ying
2024-04-15 7:04 ` Barry Song
2024-04-15 8:06 ` Barry Song
2024-04-15 8:19 ` Huang, Ying
2024-04-15 8:34 ` Barry Song
2024-04-15 8:51 ` Huang, Ying
2024-04-15 9:01 ` Barry Song
2024-04-16 1:40 ` Huang, Ying
2024-04-16 2:08 ` Barry Song
2024-04-16 3:11 ` Huang, Ying
2024-04-16 4:32 ` Barry Song
2024-04-17 0:32 ` Huang, Ying
2024-04-17 1:35 ` Barry Song
2024-04-18 5:27 ` Barry Song
2024-04-18 8:55 ` Huang, Ying
2024-04-18 9:14 ` Barry Song
2024-05-02 23:05 ` Barry Song
2024-04-09 8:26 ` [PATCH v2 2/5] mm: swap: make should_try_to_free_swap() support large-folio Barry Song
2024-04-15 7:11 ` Huang, Ying
2024-04-09 8:26 ` [PATCH v2 3/5] mm: swap_pte_batch: add an output argument to reture if all swap entries are exclusive Barry Song
2024-04-11 14:54 ` Ryan Roberts
2024-04-11 15:00 ` David Hildenbrand
2024-04-11 15:36 ` Ryan Roberts [this message]
2024-04-09 8:26 ` [PATCH v2 4/5] mm: swap: entirely map large folios found in swapcache Barry Song
2024-04-11 15:33 ` Ryan Roberts
2024-04-11 23:30 ` Barry Song
2024-04-12 11:31 ` Ryan Roberts
2024-04-15 8:37 ` Huang, Ying
2024-04-15 8:53 ` Barry Song
2024-04-16 2:25 ` Huang, Ying
2024-04-16 2:36 ` Barry Song
2024-04-16 2:39 ` Huang, Ying
2024-04-16 2:52 ` Barry Song
2024-04-16 3:17 ` Huang, Ying
2024-04-16 4:40 ` Barry Song
2024-04-18 9:55 ` Barry Song
2024-04-09 8:26 ` [PATCH v2 5/5] mm: add per-order mTHP swpin_refault counter Barry Song
2024-04-10 23:15 ` SeongJae Park
2024-04-11 1:46 ` Barry Song
2024-04-11 16:14 ` SeongJae Park
2024-04-11 15:53 ` Ryan Roberts
2024-04-11 23:01 ` Barry Song
2024-04-17 0:45 ` Huang, Ying
2024-04-17 1:16 ` Barry Song
2024-04-17 1:38 ` Huang, Ying
2024-04-17 1:48 ` Barry Song
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