On Sun, Nov 19, 2023 at 11:43 PM Huang, Ying <ying.huang@xxxxxxxxx> wrote:
>
> Kairui Song <ryncsn@xxxxxxxxx> writes:
>
> > From: Kairui Song <kasong@xxxxxxxxxxx>
> >
> > 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@xxxxxxxxxxx>
> > ---
> > 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
