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charset=UTF-8 Content-Transfer-Encoding: 8bit On Sat, Jul 27, 2024 at 4:31 AM Yosry Ahmed wrote: > > On Fri, Jul 26, 2024 at 2:47 AM Barry Song <21cnbao@gmail.com> wrote: > > > > From: Barry Song > > > > With large folios swap-in, we might need to uncharge multiple entries > > all together, it is better to introduce a helper for that. > > > > Signed-off-by: Barry Song > > --- > > include/linux/memcontrol.h | 12 ++++++++++++ > > 1 file changed, 12 insertions(+) > > > > diff --git a/include/linux/memcontrol.h b/include/linux/memcontrol.h > > index 1b79760af685..55958cbce61b 100644 > > --- a/include/linux/memcontrol.h > > +++ b/include/linux/memcontrol.h > > @@ -684,6 +684,14 @@ int mem_cgroup_swapin_charge_folio(struct folio *folio, struct mm_struct *mm, > > gfp_t gfp, swp_entry_t entry); > > void mem_cgroup_swapin_uncharge_swap(swp_entry_t entry); > > > > +static inline void mem_cgroup_swapin_uncharge_swap_nr(swp_entry_t entry, int nr) > > +{ > > + int i; > > + > > + for (i = 0; i < nr; i++, entry.val++) > > + mem_cgroup_swapin_uncharge_swap(entry); > > mem_cgroup_swapin_uncharge_swap() calls mem_cgroup_uncharge_swap() > which already takes in nr_pages, but we currently only pass 1. Would > it be better if we just make mem_cgroup_swapin_uncharge_swap() take in > nr_pages as well and pass it along to mem_cgroup_uncharge_swap(), > instead of calling it in a loop? > > This would batch the page counter, stats updates, and refcount updates > in mem_cgroup_uncharge_swap(). You may be able to observe a bit of a > performance gain with this. Good suggestion. I'll send the v6 version below after waiting for some comments on the other patches. >From 92dfbf300fd51b427d2a6833226d1b777e0b5fee Mon Sep 17 00:00:00 2001 From: Barry Song Date: Fri, 26 Jul 2024 14:33:54 +1200 Subject: [PATCH v6 2/4] mm: Introduce mem_cgroup_swapin_uncharge_swap_nr() helper for large folios swap-in With large folios swap-in, we might need to uncharge multiple entries all together, it is better to introduce a helper for that. Signed-off-by: Barry Song --- include/linux/memcontrol.h | 10 ++++++++-- mm/memcontrol.c | 7 ++++--- 2 files changed, 12 insertions(+), 5 deletions(-) diff --git a/include/linux/memcontrol.h b/include/linux/memcontrol.h index 1b79760af685..f5dd1e34654a 100644 --- a/include/linux/memcontrol.h +++ b/include/linux/memcontrol.h @@ -682,7 +682,8 @@ int mem_cgroup_hugetlb_try_charge(struct mem_cgroup *memcg, gfp_t gfp, int mem_cgroup_swapin_charge_folio(struct folio *folio, struct mm_struct *mm, gfp_t gfp, swp_entry_t entry); -void mem_cgroup_swapin_uncharge_swap(swp_entry_t entry); + +void mem_cgroup_swapin_uncharge_swap_nr(swp_entry_t entry, unsigned int nr_pages); void __mem_cgroup_uncharge(struct folio *folio); @@ -1181,7 +1182,7 @@ static inline int mem_cgroup_swapin_charge_folio(struct folio *folio, return 0; } -static inline void mem_cgroup_swapin_uncharge_swap(swp_entry_t entry) +static inline void mem_cgroup_swapin_uncharge_swap_nr(swp_entry_t entry, int nr) { } @@ -1796,6 +1797,11 @@ static inline void count_objcg_event(struct obj_cgroup *objcg, #endif /* CONFIG_MEMCG */ +static inline void mem_cgroup_swapin_uncharge_swap(swp_entry_t entry) +{ + mem_cgroup_swapin_uncharge_swap_nr(entry, 1); +} + #if defined(CONFIG_MEMCG) && defined(CONFIG_ZSWAP) bool obj_cgroup_may_zswap(struct obj_cgroup *objcg); void obj_cgroup_charge_zswap(struct obj_cgroup *objcg, size_t size); diff --git a/mm/memcontrol.c b/mm/memcontrol.c index eb92c21615eb..25657d6a133f 100644 --- a/mm/memcontrol.c +++ b/mm/memcontrol.c @@ -4573,14 +4573,15 @@ int mem_cgroup_swapin_charge_folio(struct folio *folio, struct mm_struct *mm, /* * mem_cgroup_swapin_uncharge_swap - uncharge swap slot - * @entry: swap entry for which the page is charged + * @entry: the first swap entry for which the pages are charged + * @nr_pages: number of pages which will be uncharged * * Call this function after successfully adding the charged page to swapcache. * * Note: This function assumes the page for which swap slot is being uncharged * is order 0 page. */ -void mem_cgroup_swapin_uncharge_swap(swp_entry_t entry) +void mem_cgroup_swapin_uncharge_swap_nr(swp_entry_t entry, unsigned int nr_pages) { /* * Cgroup1's unified memory+swap counter has been charged with the @@ -4600,7 +4601,7 @@ void mem_cgroup_swapin_uncharge_swap(swp_entry_t entry) * let's not wait for it. The page already received a * memory+swap charge, drop the swap entry duplicate. */ - mem_cgroup_uncharge_swap(entry, 1); + mem_cgroup_uncharge_swap(entry, nr_pages); } } -- 2.34.1 > > > +} > > + > > void __mem_cgroup_uncharge(struct folio *folio); > > > > /** > > @@ -1185,6 +1193,10 @@ static inline void mem_cgroup_swapin_uncharge_swap(swp_entry_t entry) > > { > > } > > > > +static inline void mem_cgroup_swapin_uncharge_swap_nr(swp_entry_t entry, int nr) > > +{ > > +} > > + > > static inline void mem_cgroup_uncharge(struct folio *folio) > > { > > } > > -- > > 2.34.1 > >