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-rw-r--r--mm/memory.c23
-rw-r--r--mm/shmem.c2
-rw-r--r--mm/swap_state.c215
3 files changed, 217 insertions, 23 deletions
diff --git a/mm/memory.c b/mm/memory.c
index 3dd8bb46391b..e87953775e3c 100644
--- a/mm/memory.c
+++ b/mm/memory.c
@@ -2752,16 +2752,23 @@ EXPORT_SYMBOL(unmap_mapping_range);
int do_swap_page(struct vm_fault *vmf)
{
struct vm_area_struct *vma = vmf->vma;
- struct page *page, *swapcache;
+ struct page *page = NULL, *swapcache;
struct mem_cgroup *memcg;
+ struct vma_swap_readahead swap_ra;
swp_entry_t entry;
pte_t pte;
int locked;
int exclusive = 0;
int ret = 0;
+ bool vma_readahead = swap_use_vma_readahead();
- if (!pte_unmap_same(vma->vm_mm, vmf->pmd, vmf->pte, vmf->orig_pte))
+ if (vma_readahead)
+ page = swap_readahead_detect(vmf, &swap_ra);
+ if (!pte_unmap_same(vma->vm_mm, vmf->pmd, vmf->pte, vmf->orig_pte)) {
+ if (page)
+ put_page(page);
goto out;
+ }
entry = pte_to_swp_entry(vmf->orig_pte);
if (unlikely(non_swap_entry(entry))) {
@@ -2777,10 +2784,16 @@ int do_swap_page(struct vm_fault *vmf)
goto out;
}
delayacct_set_flag(DELAYACCT_PF_SWAPIN);
- page = lookup_swap_cache(entry);
+ if (!page)
+ page = lookup_swap_cache(entry, vma_readahead ? vma : NULL,
+ vmf->address);
if (!page) {
- page = swapin_readahead(entry, GFP_HIGHUSER_MOVABLE, vma,
- vmf->address);
+ if (vma_readahead)
+ page = do_swap_page_readahead(entry,
+ GFP_HIGHUSER_MOVABLE, vmf, &swap_ra);
+ else
+ page = swapin_readahead(entry,
+ GFP_HIGHUSER_MOVABLE, vma, vmf->address);
if (!page) {
/*
* Back out if somebody else faulted in this pte
diff --git a/mm/shmem.c b/mm/shmem.c
index 47179bbe9ee7..ace53a582be5 100644
--- a/mm/shmem.c
+++ b/mm/shmem.c
@@ -1650,7 +1650,7 @@ repeat:
if (swap.val) {
/* Look it up and read it in.. */
- page = lookup_swap_cache(swap);
+ page = lookup_swap_cache(swap, NULL, 0);
if (!page) {
/* Or update major stats only when swapin succeeds?? */
if (fault_type) {
diff --git a/mm/swap_state.c b/mm/swap_state.c
index a901afe9da61..3885fef7bdf5 100644
--- a/mm/swap_state.c
+++ b/mm/swap_state.c
@@ -37,6 +37,29 @@ static const struct address_space_operations swap_aops = {
struct address_space *swapper_spaces[MAX_SWAPFILES];
static unsigned int nr_swapper_spaces[MAX_SWAPFILES];
+bool swap_vma_readahead = true;
+
+#define SWAP_RA_MAX_ORDER_DEFAULT 3
+
+static int swap_ra_max_order = SWAP_RA_MAX_ORDER_DEFAULT;
+
+#define SWAP_RA_WIN_SHIFT (PAGE_SHIFT / 2)
+#define SWAP_RA_HITS_MASK ((1UL << SWAP_RA_WIN_SHIFT) - 1)
+#define SWAP_RA_HITS_MAX SWAP_RA_HITS_MASK
+#define SWAP_RA_WIN_MASK (~PAGE_MASK & ~SWAP_RA_HITS_MASK)
+
+#define SWAP_RA_HITS(v) ((v) & SWAP_RA_HITS_MASK)
+#define SWAP_RA_WIN(v) (((v) & SWAP_RA_WIN_MASK) >> SWAP_RA_WIN_SHIFT)
+#define SWAP_RA_ADDR(v) ((v) & PAGE_MASK)
+
+#define SWAP_RA_VAL(addr, win, hits) \
+ (((addr) & PAGE_MASK) | \
+ (((win) << SWAP_RA_WIN_SHIFT) & SWAP_RA_WIN_MASK) | \
+ ((hits) & SWAP_RA_HITS_MASK))
+
+/* Initial readahead hits is 4 to start up with a small window */
+#define GET_SWAP_RA_VAL(vma) \
+ (atomic_long_read(&(vma)->swap_readahead_info) ? : 4)
#define INC_CACHE_INFO(x) do { swap_cache_info.x++; } while (0)
#define ADD_CACHE_INFO(x, nr) do { swap_cache_info.x += (nr); } while (0)
@@ -297,21 +320,36 @@ void free_pages_and_swap_cache(struct page **pages, int nr)
* lock getting page table operations atomic even if we drop the page
* lock before returning.
*/
-struct page * lookup_swap_cache(swp_entry_t entry)
+struct page *lookup_swap_cache(swp_entry_t entry, struct vm_area_struct *vma,
+ unsigned long addr)
{
struct page *page;
+ unsigned long ra_info;
+ int win, hits, readahead;
page = find_get_page(swap_address_space(entry), swp_offset(entry));
- if (page && likely(!PageTransCompound(page))) {
+ INC_CACHE_INFO(find_total);
+ if (page) {
INC_CACHE_INFO(find_success);
- if (TestClearPageReadahead(page)) {
- atomic_inc(&swapin_readahead_hits);
+ if (unlikely(PageTransCompound(page)))
+ return page;
+ readahead = TestClearPageReadahead(page);
+ if (vma) {
+ ra_info = GET_SWAP_RA_VAL(vma);
+ win = SWAP_RA_WIN(ra_info);
+ hits = SWAP_RA_HITS(ra_info);
+ if (readahead)
+ hits = min_t(int, hits + 1, SWAP_RA_HITS_MAX);
+ atomic_long_set(&vma->swap_readahead_info,
+ SWAP_RA_VAL(addr, win, hits));
+ }
+ if (readahead) {
count_vm_event(SWAP_RA_HIT);
+ if (!vma)
+ atomic_inc(&swapin_readahead_hits);
}
}
-
- INC_CACHE_INFO(find_total);
return page;
}
@@ -426,22 +464,20 @@ struct page *read_swap_cache_async(swp_entry_t entry, gfp_t gfp_mask,
return retpage;
}
-static unsigned long swapin_nr_pages(unsigned long offset)
+static unsigned int __swapin_nr_pages(unsigned long prev_offset,
+ unsigned long offset,
+ int hits,
+ int max_pages,
+ int prev_win)
{
- static unsigned long prev_offset;
- unsigned int pages, max_pages, last_ra;
- static atomic_t last_readahead_pages;
-
- max_pages = 1 << READ_ONCE(page_cluster);
- if (max_pages <= 1)
- return 1;
+ unsigned int pages, last_ra;
/*
* This heuristic has been found to work well on both sequential and
* random loads, swapping to hard disk or to SSD: please don't ask
* what the "+ 2" means, it just happens to work well, that's all.
*/
- pages = atomic_xchg(&swapin_readahead_hits, 0) + 2;
+ pages = hits + 2;
if (pages == 2) {
/*
* We can have no readahead hits to judge by: but must not get
@@ -450,7 +486,6 @@ static unsigned long swapin_nr_pages(unsigned long offset)
*/
if (offset != prev_offset + 1 && offset != prev_offset - 1)
pages = 1;
- prev_offset = offset;
} else {
unsigned int roundup = 4;
while (roundup < pages)
@@ -462,9 +497,28 @@ static unsigned long swapin_nr_pages(unsigned long offset)
pages = max_pages;
/* Don't shrink readahead too fast */
- last_ra = atomic_read(&last_readahead_pages) / 2;
+ last_ra = prev_win / 2;
if (pages < last_ra)
pages = last_ra;
+
+ return pages;
+}
+
+static unsigned long swapin_nr_pages(unsigned long offset)
+{
+ static unsigned long prev_offset;
+ unsigned int hits, pages, max_pages;
+ static atomic_t last_readahead_pages;
+
+ max_pages = 1 << READ_ONCE(page_cluster);
+ if (max_pages <= 1)
+ return 1;
+
+ hits = atomic_xchg(&swapin_readahead_hits, 0);
+ pages = __swapin_nr_pages(prev_offset, offset, hits, max_pages,
+ atomic_read(&last_readahead_pages));
+ if (!hits)
+ prev_offset = offset;
atomic_set(&last_readahead_pages, pages);
return pages;
@@ -570,3 +624,130 @@ void exit_swap_address_space(unsigned int type)
synchronize_rcu();
kvfree(spaces);
}
+
+static inline void swap_ra_clamp_pfn(struct vm_area_struct *vma,
+ unsigned long faddr,
+ unsigned long lpfn,
+ unsigned long rpfn,
+ unsigned long *start,
+ unsigned long *end)
+{
+ *start = max3(lpfn, PFN_DOWN(vma->vm_start),
+ PFN_DOWN(faddr & PMD_MASK));
+ *end = min3(rpfn, PFN_DOWN(vma->vm_end),
+ PFN_DOWN((faddr & PMD_MASK) + PMD_SIZE));
+}
+
+struct page *swap_readahead_detect(struct vm_fault *vmf,
+ struct vma_swap_readahead *swap_ra)
+{
+ struct vm_area_struct *vma = vmf->vma;
+ unsigned long swap_ra_info;
+ struct page *page;
+ swp_entry_t entry;
+ unsigned long faddr, pfn, fpfn;
+ unsigned long start, end;
+ pte_t *pte;
+ unsigned int max_win, hits, prev_win, win, left;
+#ifndef CONFIG_64BIT
+ pte_t *tpte;
+#endif
+
+ faddr = vmf->address;
+ entry = pte_to_swp_entry(vmf->orig_pte);
+ if ((unlikely(non_swap_entry(entry))))
+ return NULL;
+ page = lookup_swap_cache(entry, vma, faddr);
+ if (page)
+ return page;
+
+ max_win = 1 << READ_ONCE(swap_ra_max_order);
+ if (max_win == 1) {
+ swap_ra->win = 1;
+ return NULL;
+ }
+
+ fpfn = PFN_DOWN(faddr);
+ swap_ra_info = GET_SWAP_RA_VAL(vma);
+ pfn = PFN_DOWN(SWAP_RA_ADDR(swap_ra_info));
+ prev_win = SWAP_RA_WIN(swap_ra_info);
+ hits = SWAP_RA_HITS(swap_ra_info);
+ swap_ra->win = win = __swapin_nr_pages(pfn, fpfn, hits,
+ max_win, prev_win);
+ atomic_long_set(&vma->swap_readahead_info,
+ SWAP_RA_VAL(faddr, win, 0));
+
+ if (win == 1)
+ return NULL;
+
+ /* Copy the PTEs because the page table may be unmapped */
+ if (fpfn == pfn + 1)
+ swap_ra_clamp_pfn(vma, faddr, fpfn, fpfn + win, &start, &end);
+ else if (pfn == fpfn + 1)
+ swap_ra_clamp_pfn(vma, faddr, fpfn - win + 1, fpfn + 1,
+ &start, &end);
+ else {
+ left = (win - 1) / 2;
+ swap_ra_clamp_pfn(vma, faddr, fpfn - left, fpfn + win - left,
+ &start, &end);
+ }
+ swap_ra->nr_pte = end - start;
+ swap_ra->offset = fpfn - start;
+ pte = vmf->pte - swap_ra->offset;
+#ifdef CONFIG_64BIT
+ swap_ra->ptes = pte;
+#else
+ tpte = swap_ra->ptes;
+ for (pfn = start; pfn != end; pfn++)
+ *tpte++ = *pte++;
+#endif
+
+ return NULL;
+}
+
+struct page *do_swap_page_readahead(swp_entry_t fentry, gfp_t gfp_mask,
+ struct vm_fault *vmf,
+ struct vma_swap_readahead *swap_ra)
+{
+ struct blk_plug plug;
+ struct vm_area_struct *vma = vmf->vma;
+ struct page *page;
+ pte_t *pte, pentry;
+ swp_entry_t entry;
+ unsigned int i;
+ bool page_allocated;
+
+ if (swap_ra->win == 1)
+ goto skip;
+
+ blk_start_plug(&plug);
+ for (i = 0, pte = swap_ra->ptes; i < swap_ra->nr_pte;
+ i++, pte++) {
+ pentry = *pte;
+ if (pte_none(pentry))
+ continue;
+ if (pte_present(pentry))
+ continue;
+ entry = pte_to_swp_entry(pentry);
+ if (unlikely(non_swap_entry(entry)))
+ continue;
+ page = __read_swap_cache_async(entry, gfp_mask, vma,
+ vmf->address, &page_allocated);
+ if (!page)
+ continue;
+ if (page_allocated) {
+ swap_readpage(page, false);
+ if (i != swap_ra->offset &&
+ likely(!PageTransCompound(page))) {
+ SetPageReadahead(page);
+ count_vm_event(SWAP_RA);
+ }
+ }
+ put_page(page);
+ }
+ blk_finish_plug(&plug);
+ lru_add_drain();
+skip:
+ return read_swap_cache_async(fentry, gfp_mask, vma, vmf->address,
+ swap_ra->win == 1);
+}
generated by cgit v1.2.1 (git 2.18.0) at 2024-11-16 19:17:26 +0000