From: Miaohe Lin <linmiaohe@huawei.com>
To: Oscar Salvador <osalvador@suse.de>
Cc: <akpm@linux-foundation.org>, <ying.huang@intel.com>,
<songmuchun@bytedance.com>, <hch@infradead.org>,
<willy@infradead.org>, <linux-mm@kvack.org>,
<linux-kernel@vger.kernel.org>
Subject: Re: [PATCH v2 2/9] mm/vmscan: remove unneeded can_split_huge_page check
Date: Tue, 12 Apr 2022 21:42:16 +0800 [thread overview]
Message-ID: <7455b680-3d89-5d3e-ba0e-6e4358b114a2@huawei.com> (raw)
In-Reply-To: <YlU/h0fdE1L846Bd@localhost.localdomain>
On 2022/4/12 16:59, Oscar Salvador wrote:
> On Sat, Apr 09, 2022 at 05:34:53PM +0800, Miaohe Lin wrote:
>> We don't need to check can_split_folio() because folio_maybe_dma_pinned()
>> is checked before. It will avoid the long term pinned pages to be swapped
>> out. And we can live with short term pinned pages. Without can_split_folio
>> checking we can simplify the code. Also activate_locked can be changed to
>> keep_locked as it's just short term pinning.
>
> What do you mean by "we can live with short term pinned pages"?
> Does it mean that it was not pinned when we check
> folio_maybe_dma_pinned() but now it is?
>
> To me it looks like the pinning is fluctuating and we rely on
> split_folio_to_list() to see whether we succeed or not, and if not
> we give it another spin in the next round?
Yes. Short term pinned pages is relative to long term pinned pages and these pages won't be
pinned for a noticeable time. So it's expected to split the folio successfully in the next
round as the pinning is really fluctuating. Or am I miss something?
Many thanks for your comment and reply!
>
>> Suggested-by: Huang, Ying <ying.huang@intel.com>
>> Signed-off-by: Miaohe Lin <linmiaohe@huawei.com>
>> ---
>> mm/vmscan.c | 22 ++++++++--------------
>> 1 file changed, 8 insertions(+), 14 deletions(-)
>>
>> diff --git a/mm/vmscan.c b/mm/vmscan.c
>> index 4a76be47bed1..01f5db75a507 100644
>> --- a/mm/vmscan.c
>> +++ b/mm/vmscan.c
>> @@ -1711,20 +1711,14 @@ static unsigned int shrink_page_list(struct list_head *page_list,
>> goto keep_locked;
>> if (folio_maybe_dma_pinned(folio))
>> goto keep_locked;
>> - if (PageTransHuge(page)) {
>> - /* cannot split THP, skip it */
>> - if (!can_split_folio(folio, NULL))
>> - goto activate_locked;
>> - /*
>> - * Split pages without a PMD map right
>> - * away. Chances are some or all of the
>> - * tail pages can be freed without IO.
>> - */
>> - if (!folio_entire_mapcount(folio) &&
>> - split_folio_to_list(folio,
>> - page_list))
>> - goto activate_locked;
>> - }
>> + /*
>> + * Split pages without a PMD map right
>> + * away. Chances are some or all of the
>> + * tail pages can be freed without IO.
>> + */
>> + if (PageTransHuge(page) && !folio_entire_mapcount(folio) &&
>> + split_folio_to_list(folio, page_list))
>> + goto keep_locked;
>> if (!add_to_swap(page)) {
>> if (!PageTransHuge(page))
>> goto activate_locked_split;
>> --
>> 2.23.0
>>
>>
>
next prev parent reply other threads:[~2022-04-12 13:42 UTC|newest]
Thread overview: 33+ messages / expand[flat|nested] mbox.gz Atom feed top
2022-04-09 9:34 [PATCH v2 0/9] A few cleanup and fixup patches for vmscan Miaohe Lin
2022-04-09 9:34 ` [PATCH v2 1/9] mm/vmscan: add a comment about MADV_FREE pages check in folio_check_dirty_writeback Miaohe Lin
2022-04-11 11:50 ` ying.huang
2022-04-12 3:07 ` Miaohe Lin
2022-04-11 14:16 ` Christoph Hellwig
2022-04-12 3:15 ` Miaohe Lin
2022-04-12 8:44 ` Oscar Salvador
2022-04-09 9:34 ` [PATCH v2 2/9] mm/vmscan: remove unneeded can_split_huge_page check Miaohe Lin
2022-04-11 14:18 ` Christoph Hellwig
2022-04-12 3:14 ` Miaohe Lin
2022-04-12 0:52 ` ying.huang
2022-04-12 8:59 ` Oscar Salvador
2022-04-12 13:42 ` Miaohe Lin [this message]
2022-04-12 14:59 ` David Hildenbrand
2022-04-13 1:26 ` ying.huang
2022-04-13 2:17 ` Miaohe Lin
2022-04-15 3:07 ` ying.huang
2022-04-16 2:34 ` Miaohe Lin
2022-04-09 9:34 ` [PATCH v2 3/9] mm/vmscan: introduce helper function reclaim_page_list() Miaohe Lin
2022-04-09 13:44 ` Matthew Wilcox
2022-04-11 1:53 ` Miaohe Lin
2022-04-11 3:17 ` Matthew Wilcox
2022-04-11 3:26 ` Miaohe Lin
2022-04-09 9:34 ` [PATCH v2 4/9] mm/vmscan: save a bit of stack space in shrink_lruvec Miaohe Lin
2022-04-12 0:57 ` ying.huang
2022-04-12 3:13 ` Miaohe Lin
2022-04-09 9:34 ` [PATCH v2 5/9] mm/vmscan: activate swap-backed executable folios after first usage Miaohe Lin
2022-04-12 0:59 ` ying.huang
2022-04-09 9:34 ` [PATCH v2 6/9] mm/vmscan: take all base pages of THP into account when race with speculative reference Miaohe Lin
2022-04-09 9:34 ` [PATCH v2 7/9] mm/vmscan: take min_slab_pages into account when try to call shrink_node Miaohe Lin
2022-04-12 1:36 ` ying.huang
2022-04-09 9:34 ` [PATCH v2 8/9] mm/vmscan: remove obsolete comment in kswapd_run Miaohe Lin
2022-04-09 9:35 ` [PATCH v2 9/9] mm/vmscan: use helper folio_is_file_lru() Miaohe Lin
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