diff mbox series

[09/24] mm/swap: inline __swap_count

Message ID 20231119194740.94101-10-ryncsn@gmail.com
State New
Headers
Series Swapin path refactor for optimization and bugfix |

Commit Message

Kairui Song Nov. 19, 2023, 7:47 p.m. UTC 
  From: Kairui Song <kasong@tencent.com>

There is only one caller in swap subsystem now, where it can be inline
smoothly, avoid the memory access and function call overheads.

Signed-off-by: Kairui Song <kasong@tencent.com>
---
 include/linux/swap.h | 6 ------
 mm/swap_state.c      | 6 +++---
 mm/swapfile.c        | 8 --------
 3 files changed, 3 insertions(+), 17 deletions(-)

Comments

Huang, Ying Nov. 20, 2023, 7:41 a.m. UTC | #1 
Kairui Song <ryncsn@gmail.com> writes:

> From: Kairui Song <kasong@tencent.com>
>
> There is only one caller in swap subsystem now, where it can be inline
> smoothly, avoid the memory access and function call overheads.
>
> Signed-off-by: Kairui Song <kasong@tencent.com>
> ---
>  include/linux/swap.h | 6 ------
>  mm/swap_state.c      | 6 +++---
>  mm/swapfile.c        | 8 --------
>  3 files changed, 3 insertions(+), 17 deletions(-)
>
> diff --git a/include/linux/swap.h b/include/linux/swap.h
> index 2401990d954d..64a37819a9b3 100644
> --- a/include/linux/swap.h
> +++ b/include/linux/swap.h
> @@ -485,7 +485,6 @@ int swap_type_of(dev_t device, sector_t offset);
>  int find_first_swap(dev_t *device);
>  extern unsigned int count_swap_pages(int, int);
>  extern sector_t swapdev_block(int, pgoff_t);
> -extern int __swap_count(swp_entry_t entry);
>  extern int swap_swapcount(struct swap_info_struct *si, swp_entry_t entry);
>  extern int swp_swapcount(swp_entry_t entry);
>  extern struct swap_info_struct *page_swap_info(struct page *);
> @@ -559,11 +558,6 @@ static inline void put_swap_folio(struct folio *folio, swp_entry_t swp)
>  {
>  }
>  
> -static inline int __swap_count(swp_entry_t entry)
> -{
> -	return 0;
> -}
> -
>  static inline int swap_swapcount(struct swap_info_struct *si, swp_entry_t entry)
>  {
>  	return 0;
> diff --git a/mm/swap_state.c b/mm/swap_state.c
> index fb78f7f18ed7..d87c20f9f7ec 100644
> --- a/mm/swap_state.c
> +++ b/mm/swap_state.c
> @@ -316,9 +316,9 @@ void free_pages_and_swap_cache(struct encoded_page **pages, int nr)
>  	release_pages(pages, nr);
>  }
>  
> -static inline bool swap_use_no_readahead(struct swap_info_struct *si, swp_entry_t entry)
> +static inline bool swap_use_no_readahead(struct swap_info_struct *si, pgoff_t offset)
>  {
> -	return data_race(si->flags & SWP_SYNCHRONOUS_IO) && __swap_count(entry) == 1;
> +	return data_race(si->flags & SWP_SYNCHRONOUS_IO) && swap_count(si->swap_map[offset]) == 1;
>  }
>  
>  static inline bool swap_use_vma_readahead(struct swap_info_struct *si)
> @@ -928,7 +928,7 @@ struct page *swapin_readahead(swp_entry_t entry, gfp_t gfp_mask,
>  
>  	si = swp_swap_info(entry);
>  	mpol = get_vma_policy(vmf->vma, vmf->address, 0, &ilx);
> -	if (swap_use_no_readahead(si, entry)) {
> +	if (swap_use_no_readahead(si, swp_offset(entry))) {
>  		page = swapin_no_readahead(entry, gfp_mask, mpol, ilx, vmf->vma->vm_mm);
>  		cached = false;
>  	} else if (swap_use_vma_readahead(si)) {
> diff --git a/mm/swapfile.c b/mm/swapfile.c
> index a8ae472ed2b6..e15a6c464a38 100644
> --- a/mm/swapfile.c
> +++ b/mm/swapfile.c
> @@ -1431,14 +1431,6 @@ void swapcache_free_entries(swp_entry_t *entries, int n)
>  		spin_unlock(&p->lock);
>  }
>  
> -int __swap_count(swp_entry_t entry)
> -{
> -	struct swap_info_struct *si = swp_swap_info(entry);
> -	pgoff_t offset = swp_offset(entry);
> -
> -	return swap_count(si->swap_map[offset]);
> -}
> -

I'd rather keep __swap_count() in the original place together with other
swap count related functions.  And si->swap_map[] was hided in
swapfile.c before.  I don't think the change will have any real
performance improvement.

>  /*
>   * How many references to @entry are currently swapped out?
>   * This does not give an exact answer when swap count is continued,

--
Best Regards,
Huang, Ying
Chris Li Nov. 21, 2023, 8:02 a.m. UTC | #2 
On Sun, Nov 19, 2023 at 11:43 PM Huang, Ying <ying.huang@intel.com> wrote:
>
> Kairui Song <ryncsn@gmail.com> writes:
>
> > From: Kairui Song <kasong@tencent.com>
> >
> > There is only one caller in swap subsystem now, where it can be inline
> > smoothly, avoid the memory access and function call overheads.
> >
> > Signed-off-by: Kairui Song <kasong@tencent.com>
> > ---
> >  include/linux/swap.h | 6 ------
> >  mm/swap_state.c      | 6 +++---
> >  mm/swapfile.c        | 8 --------
> >  3 files changed, 3 insertions(+), 17 deletions(-)
> >
> > diff --git a/include/linux/swap.h b/include/linux/swap.h
> > index 2401990d954d..64a37819a9b3 100644
> > --- a/include/linux/swap.h
> > +++ b/include/linux/swap.h
> > @@ -485,7 +485,6 @@ int swap_type_of(dev_t device, sector_t offset);
> >  int find_first_swap(dev_t *device);
> >  extern unsigned int count_swap_pages(int, int);
> >  extern sector_t swapdev_block(int, pgoff_t);
> > -extern int __swap_count(swp_entry_t entry);
> >  extern int swap_swapcount(struct swap_info_struct *si, swp_entry_t entry);
> >  extern int swp_swapcount(swp_entry_t entry);
> >  extern struct swap_info_struct *page_swap_info(struct page *);
> > @@ -559,11 +558,6 @@ static inline void put_swap_folio(struct folio *folio, swp_entry_t swp)
> >  {
> >  }
> >
> > -static inline int __swap_count(swp_entry_t entry)
> > -{
> > -     return 0;
> > -}
> > -
> >  static inline int swap_swapcount(struct swap_info_struct *si, swp_entry_t entry)
> >  {
> >       return 0;
> > diff --git a/mm/swap_state.c b/mm/swap_state.c
> > index fb78f7f18ed7..d87c20f9f7ec 100644
> > --- a/mm/swap_state.c
> > +++ b/mm/swap_state.c
> > @@ -316,9 +316,9 @@ void free_pages_and_swap_cache(struct encoded_page **pages, int nr)
> >       release_pages(pages, nr);
> >  }
> >
> > -static inline bool swap_use_no_readahead(struct swap_info_struct *si, swp_entry_t entry)
> > +static inline bool swap_use_no_readahead(struct swap_info_struct *si, pgoff_t offset)
> >  {
> > -     return data_race(si->flags & SWP_SYNCHRONOUS_IO) && __swap_count(entry) == 1;
> > +     return data_race(si->flags & SWP_SYNCHRONOUS_IO) && swap_count(si->swap_map[offset]) == 1;
> >  }
> >
> >  static inline bool swap_use_vma_readahead(struct swap_info_struct *si)
> > @@ -928,7 +928,7 @@ struct page *swapin_readahead(swp_entry_t entry, gfp_t gfp_mask,
> >
> >       si = swp_swap_info(entry);
> >       mpol = get_vma_policy(vmf->vma, vmf->address, 0, &ilx);
> > -     if (swap_use_no_readahead(si, entry)) {
> > +     if (swap_use_no_readahead(si, swp_offset(entry))) {
> >               page = swapin_no_readahead(entry, gfp_mask, mpol, ilx, vmf->vma->vm_mm);
> >               cached = false;
> >       } else if (swap_use_vma_readahead(si)) {
> > diff --git a/mm/swapfile.c b/mm/swapfile.c
> > index a8ae472ed2b6..e15a6c464a38 100644
> > --- a/mm/swapfile.c
> > +++ b/mm/swapfile.c
> > @@ -1431,14 +1431,6 @@ void swapcache_free_entries(swp_entry_t *entries, int n)
> >               spin_unlock(&p->lock);
> >  }
> >
> > -int __swap_count(swp_entry_t entry)
> > -{
> > -     struct swap_info_struct *si = swp_swap_info(entry);
> > -     pgoff_t offset = swp_offset(entry);
> > -
> > -     return swap_count(si->swap_map[offset]);
> > -}
> > -
>
> I'd rather keep __swap_count() in the original place together with other
> swap count related functions.  And si->swap_map[] was hided in
> swapfile.c before.  I don't think the change will have any real
> performance improvement.

I agree with Ying here. Does not seem to have value high enough to
justify a patch by itself.

Chris
diff mbox series

Patch

diff --git a/include/linux/swap.h b/include/linux/swap.h
index 2401990d954d..64a37819a9b3 100644
--- a/include/linux/swap.h
+++ b/include/linux/swap.h
@@ -485,7 +485,6 @@  int swap_type_of(dev_t device, sector_t offset);
 int find_first_swap(dev_t *device);
 extern unsigned int count_swap_pages(int, int);
 extern sector_t swapdev_block(int, pgoff_t);
-extern int __swap_count(swp_entry_t entry);
 extern int swap_swapcount(struct swap_info_struct *si, swp_entry_t entry);
 extern int swp_swapcount(swp_entry_t entry);
 extern struct swap_info_struct *page_swap_info(struct page *);
@@ -559,11 +558,6 @@  static inline void put_swap_folio(struct folio *folio, swp_entry_t swp)
 {
 }
 
-static inline int __swap_count(swp_entry_t entry)
-{
-	return 0;
-}
-
 static inline int swap_swapcount(struct swap_info_struct *si, swp_entry_t entry)
 {
 	return 0;
diff --git a/mm/swap_state.c b/mm/swap_state.c
index fb78f7f18ed7..d87c20f9f7ec 100644
--- a/mm/swap_state.c
+++ b/mm/swap_state.c
@@ -316,9 +316,9 @@  void free_pages_and_swap_cache(struct encoded_page **pages, int nr)
 	release_pages(pages, nr);
 }
 
-static inline bool swap_use_no_readahead(struct swap_info_struct *si, swp_entry_t entry)
+static inline bool swap_use_no_readahead(struct swap_info_struct *si, pgoff_t offset)
 {
-	return data_race(si->flags & SWP_SYNCHRONOUS_IO) && __swap_count(entry) == 1;
+	return data_race(si->flags & SWP_SYNCHRONOUS_IO) && swap_count(si->swap_map[offset]) == 1;
 }
 
 static inline bool swap_use_vma_readahead(struct swap_info_struct *si)
@@ -928,7 +928,7 @@  struct page *swapin_readahead(swp_entry_t entry, gfp_t gfp_mask,
 
 	si = swp_swap_info(entry);
 	mpol = get_vma_policy(vmf->vma, vmf->address, 0, &ilx);
-	if (swap_use_no_readahead(si, entry)) {
+	if (swap_use_no_readahead(si, swp_offset(entry))) {
 		page = swapin_no_readahead(entry, gfp_mask, mpol, ilx, vmf->vma->vm_mm);
 		cached = false;
 	} else if (swap_use_vma_readahead(si)) {
diff --git a/mm/swapfile.c b/mm/swapfile.c
index a8ae472ed2b6..e15a6c464a38 100644
--- a/mm/swapfile.c
+++ b/mm/swapfile.c
@@ -1431,14 +1431,6 @@  void swapcache_free_entries(swp_entry_t *entries, int n)
 		spin_unlock(&p->lock);
 }
 
-int __swap_count(swp_entry_t entry)
-{
-	struct swap_info_struct *si = swp_swap_info(entry);
-	pgoff_t offset = swp_offset(entry);
-
-	return swap_count(si->swap_map[offset]);
-}
-
 /*
  * How many references to @entry are currently swapped out?
  * This does not give an exact answer when swap count is continued,