From: Kairui Song <kasong@xxxxxxxxxxx> Introduce swapin_entry which merges swapin_readahead and swapin_direct making it the main entry for swapin pages, and use a unified swapin policy. This commit makes swapoff make use of this new helper and now swapping off a 10G ZRAM (lzo-rle) is faster since readahead is skipped. Before: time swapoff /dev/zram0 real 0m12.337s user 0m0.001s sys 0m12.329s After: time swapoff /dev/zram0 real 0m9.728s user 0m0.001s sys 0m9.719s Signed-off-by: Kairui Song <kasong@xxxxxxxxxxx> --- mm/memory.c | 21 +++++++-------------- mm/swap.h | 16 ++++------------ mm/swap_state.c | 49 +++++++++++++++++++++++++++++++++---------------- mm/swapfile.c | 7 ++----- 4 files changed, 46 insertions(+), 47 deletions(-) diff --git a/mm/memory.c b/mm/memory.c index 0165c8cad489..b56254a875f8 100644 --- a/mm/memory.c +++ b/mm/memory.c @@ -3801,6 +3801,7 @@ vm_fault_t do_swap_page(struct vm_fault *vmf) rmap_t rmap_flags = RMAP_NONE; bool exclusive = false; swp_entry_t entry; + bool swapcached; pte_t pte; vm_fault_t ret = 0; @@ -3864,21 +3865,13 @@ vm_fault_t do_swap_page(struct vm_fault *vmf) swapcache = folio; if (!folio) { - if (data_race(si->flags & SWP_SYNCHRONOUS_IO) && - __swap_count(entry) == 1) { - /* skip swapcache and readahead */ - folio = swapin_direct(entry, GFP_HIGHUSER_MOVABLE, vmf); - if (folio) - page = &folio->page; + folio = swapin_entry(entry, GFP_HIGHUSER_MOVABLE, + vmf, &swapcached); + if (folio) { + page = folio_file_page(folio, swp_offset(entry)); + if (swapcached) + swapcache = folio; } else { - page = swapin_readahead(entry, GFP_HIGHUSER_MOVABLE, - vmf); - if (page) - folio = page_folio(page); - swapcache = folio; - } - - if (!folio) { /* * Back out if somebody else faulted in this pte * while we released the pte lock. diff --git a/mm/swap.h b/mm/swap.h index 83eab7b67e77..502a2801f817 100644 --- a/mm/swap.h +++ b/mm/swap.h @@ -54,10 +54,8 @@ struct folio *__read_swap_cache_async(swp_entry_t entry, gfp_t gfp_flags, bool skip_if_exists); struct folio *swap_cluster_readahead(swp_entry_t entry, gfp_t flag, struct mempolicy *mpol, pgoff_t ilx); -struct page *swapin_readahead(swp_entry_t entry, gfp_t flag, - struct vm_fault *vmf); -struct folio *swapin_direct(swp_entry_t entry, gfp_t flag, - struct vm_fault *vmf); +struct folio *swapin_entry(swp_entry_t entry, gfp_t flag, + struct vm_fault *vmf, bool *swapcached); static inline unsigned int folio_swap_flags(struct folio *folio) { @@ -88,14 +86,8 @@ static inline struct folio *swap_cluster_readahead(swp_entry_t entry, return NULL; } -struct folio *swapin_direct(swp_entry_t entry, gfp_t flag, - struct vm_fault *vmf) -{ - return NULL; -} - -static inline struct page *swapin_readahead(swp_entry_t swp, gfp_t gfp_mask, - struct vm_fault *vmf) +static inline struct folio *swapin_entry(swp_entry_t swp, gfp_t gfp_mask, + struct vm_fault *vmf, bool *swapcached) { return NULL; } diff --git a/mm/swap_state.c b/mm/swap_state.c index d39c5369da21..66ff187aa5d3 100644 --- a/mm/swap_state.c +++ b/mm/swap_state.c @@ -316,6 +316,11 @@ 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) +{ + return data_race(si->flags & SWP_SYNCHRONOUS_IO) && __swap_count(entry) == 1; +} + static inline bool swap_use_vma_readahead(void) { return READ_ONCE(enable_vma_readahead) && !atomic_read(&nr_rotate_swap); @@ -870,8 +875,8 @@ static struct folio *swap_vma_readahead(swp_entry_t targ_entry, gfp_t gfp_mask, * Returns the struct folio for entry and addr after the swap entry is read * in. */ -struct folio *swapin_direct(swp_entry_t entry, gfp_t gfp_mask, - struct vm_fault *vmf) +static struct folio *swapin_direct(swp_entry_t entry, gfp_t gfp_mask, + struct vm_fault *vmf) { struct vm_area_struct *vma = vmf->vma; struct folio *folio; @@ -908,33 +913,45 @@ struct folio *swapin_direct(swp_entry_t entry, gfp_t gfp_mask, } /** - * swapin_readahead - swap in pages in hope we need them soon + * swapin_entry - swap in a page from swap entry * @entry: swap entry of this memory * @gfp_mask: memory allocation flags * @vmf: fault information + * @swapcached: pointer to a bool used as indicator if the + * page is swapped in through swapcache. * * Returns the struct page for entry and addr, after queueing swapin. * - * It's a main entry function for swap readahead. By the configuration, + * It's a main entry function for swap in. By the configuration, * it will read ahead blocks by cluster-based(ie, physical disk based) - * or vma-based(ie, virtual address based on faulty address) readahead. + * or vma-based(ie, virtual address based on faulty address) readahead, + * or skip the readahead (ie, ramdisk based swap device). */ -struct page *swapin_readahead(swp_entry_t entry, gfp_t gfp_mask, - struct vm_fault *vmf) +struct folio *swapin_entry(swp_entry_t entry, gfp_t gfp_mask, + struct vm_fault *vmf, bool *swapcached) { struct mempolicy *mpol; - pgoff_t ilx; struct folio *folio; + pgoff_t ilx; + bool cached; - mpol = get_vma_policy(vmf->vma, vmf->address, 0, &ilx); - folio = swap_use_vma_readahead() ? - swap_vma_readahead(entry, gfp_mask, mpol, ilx, vmf) : - swap_cluster_readahead(entry, gfp_mask, mpol, ilx); - mpol_cond_put(mpol); + if (swap_use_no_readahead(swp_swap_info(entry), entry)) { + folio = swapin_direct(entry, gfp_mask, vmf); + cached = false; + } else { + mpol = get_vma_policy(vmf->vma, vmf->address, 0, &ilx); + if (swap_use_vma_readahead()) + folio = swap_vma_readahead(entry, gfp_mask, mpol, ilx, vmf); + else + folio = swap_cluster_readahead(entry, gfp_mask, mpol, ilx); + mpol_cond_put(mpol); + cached = true; + } - if (!folio) - return NULL; - return folio_file_page(folio, swp_offset(entry)); + if (swapcached) + *swapcached = cached; + + return folio; } #ifdef CONFIG_SYSFS diff --git a/mm/swapfile.c b/mm/swapfile.c index f7271504aa0a..ce4e6c10dce7 100644 --- a/mm/swapfile.c +++ b/mm/swapfile.c @@ -1866,7 +1866,6 @@ static int unuse_pte_range(struct vm_area_struct *vma, pmd_t *pmd, folio = swap_cache_get_folio(entry, vma, addr); if (!folio) { - struct page *page; struct vm_fault vmf = { .vma = vma, .address = addr, @@ -1874,10 +1873,8 @@ static int unuse_pte_range(struct vm_area_struct *vma, pmd_t *pmd, .pmd = pmd, }; - page = swapin_readahead(entry, GFP_HIGHUSER_MOVABLE, - &vmf); - if (page) - folio = page_folio(page); + folio = swapin_entry(entry, GFP_HIGHUSER_MOVABLE, + &vmf, NULL); } if (!folio) { /* -- 2.43.0