diff mbox series

[v2,7/9] mm/swap: avoid a duplicated swap cache lookup for SWP_SYNCHRONOUS_IO

Message ID 20240102175338.62012-8-ryncsn@gmail.com (mailing list archive)
State New
Headers show
Series swapin refactor for optimization and unified readahead | expand

Commit Message

Kairui Song Jan. 2, 2024, 5:53 p.m. UTC 
From: Kairui Song <kasong@tencent.com>

When a xa_value is returned by the cache lookup, keep it to be used
later for workingset refault check instead of doing the looking up again
in swapin_no_readahead.

This does have a side effect of making swapoff also triggers workingset
check, but should be fine since swapoff does affect the workload in many
ways already.

After this commit, swappin is about 4% faster for ZRAM, micro benchmark
result which use madvise to swap out 10G zero-filled data to ZRAM then
read them in:

Before: 11143285 us
After:  10692644 us (+4.1%)

Signed-off-by: Kairui Song <kasong@tencent.com>
---
 mm/shmem.c      |  2 +-
 mm/swap.h       |  3 ++-
 mm/swap_state.c | 24 +++++++++++++-----------
 3 files changed, 16 insertions(+), 13 deletions(-)

Comments

kernel test robot Jan. 3, 2024, 12:50 p.m. UTC | #1 
Hi Kairui,

kernel test robot noticed the following build warnings:

[auto build test WARNING on akpm-mm/mm-everything]
[also build test WARNING on next-20240103]
[cannot apply to linus/master v6.7-rc8]
[If your patch is applied to the wrong git tree, kindly drop us a note.
And when submitting patch, we suggest to use '--base' as documented in
https://git-scm.com/docs/git-format-patch#_base_tree_information]

url:    https://github.com/intel-lab-lkp/linux/commits/Kairui-Song/mm-swapfile-c-add-back-some-comment/20240103-015650
base:   https://git.kernel.org/pub/scm/linux/kernel/git/akpm/mm.git mm-everything
patch link:    https://lore.kernel.org/r/20240102175338.62012-8-ryncsn%40gmail.com
patch subject: [PATCH v2 7/9] mm/swap: avoid a duplicated swap cache lookup for SWP_SYNCHRONOUS_IO
config: arc-vdk_hs38_smp_defconfig (https://download.01.org/0day-ci/archive/20240103/202401032010.yrIDf885-lkp@intel.com/config)
compiler: arc-elf-gcc (GCC) 13.2.0
reproduce (this is a W=1 build): (https://download.01.org/0day-ci/archive/20240103/202401032010.yrIDf885-lkp@intel.com/reproduce)

If you fix the issue in a separate patch/commit (i.e. not just a new version of
the same patch/commit), kindly add following tags
| Reported-by: kernel test robot <lkp@intel.com>
| Closes: https://lore.kernel.org/oe-kbuild-all/202401032010.yrIDf885-lkp@intel.com/

All warnings (new ones prefixed by >>):

>> mm/swap_state.c:884: warning: Function parameter or member 'shadow' not described in 'swapin_direct'


vim +884 mm/swap_state.c

d9bfcfdc41e8e5 Huang Ying  2017-09-06  872  
b16a5db0ccd159 Kairui Song 2024-01-03  873  /**
b16a5db0ccd159 Kairui Song 2024-01-03  874   * swapin_direct - swap in folios skipping swap cache and readahead
b16a5db0ccd159 Kairui Song 2024-01-03  875   * @entry: swap entry of this memory
b16a5db0ccd159 Kairui Song 2024-01-03  876   * @gfp_mask: memory allocation flags
b16a5db0ccd159 Kairui Song 2024-01-03  877   * @vmf: fault information
b16a5db0ccd159 Kairui Song 2024-01-03  878   *
b16a5db0ccd159 Kairui Song 2024-01-03  879   * Returns the struct folio for entry and addr after the swap entry is read
b16a5db0ccd159 Kairui Song 2024-01-03  880   * in.
b16a5db0ccd159 Kairui Song 2024-01-03  881   */
983c0b807f7eda Kairui Song 2024-01-03  882  static struct folio *swapin_direct(swp_entry_t entry, gfp_t gfp_mask,
cd81b9fd3de376 Kairui Song 2024-01-03  883  				  struct vm_fault *vmf, void *shadow)
b16a5db0ccd159 Kairui Song 2024-01-03 @884  {
b16a5db0ccd159 Kairui Song 2024-01-03  885  	struct vm_area_struct *vma = vmf->vma;
b16a5db0ccd159 Kairui Song 2024-01-03  886  	struct folio *folio;
b16a5db0ccd159 Kairui Song 2024-01-03  887  
b16a5db0ccd159 Kairui Song 2024-01-03  888  	/* skip swapcache */
b16a5db0ccd159 Kairui Song 2024-01-03  889  	folio = vma_alloc_folio(GFP_HIGHUSER_MOVABLE, 0,
b16a5db0ccd159 Kairui Song 2024-01-03  890  				vma, vmf->address, false);
b16a5db0ccd159 Kairui Song 2024-01-03  891  	if (folio) {
9e22e4254bdb8c Kairui Song 2024-01-03  892  		if (mem_cgroup_swapin_charge_folio(folio, NULL,
64ae20cbed3891 Kairui Song 2024-01-03  893  						   GFP_KERNEL, entry)) {
b16a5db0ccd159 Kairui Song 2024-01-03  894  			folio_put(folio);
b16a5db0ccd159 Kairui Song 2024-01-03  895  			return NULL;
b16a5db0ccd159 Kairui Song 2024-01-03  896  		}
64ae20cbed3891 Kairui Song 2024-01-03  897  
64ae20cbed3891 Kairui Song 2024-01-03  898  		__folio_set_locked(folio);
64ae20cbed3891 Kairui Song 2024-01-03  899  		__folio_set_swapbacked(folio);
64ae20cbed3891 Kairui Song 2024-01-03  900  
b16a5db0ccd159 Kairui Song 2024-01-03  901  		mem_cgroup_swapin_uncharge_swap(entry);
b16a5db0ccd159 Kairui Song 2024-01-03  902  
b16a5db0ccd159 Kairui Song 2024-01-03  903  		if (shadow)
b16a5db0ccd159 Kairui Song 2024-01-03  904  			workingset_refault(folio, shadow);
b16a5db0ccd159 Kairui Song 2024-01-03  905  
b16a5db0ccd159 Kairui Song 2024-01-03  906  		folio_add_lru(folio);
b16a5db0ccd159 Kairui Song 2024-01-03  907  
b16a5db0ccd159 Kairui Song 2024-01-03  908  		/* To provide entry to swap_read_folio() */
b16a5db0ccd159 Kairui Song 2024-01-03  909  		folio->swap = entry;
b16a5db0ccd159 Kairui Song 2024-01-03  910  		swap_read_folio(folio, true, NULL);
b16a5db0ccd159 Kairui Song 2024-01-03  911  		folio->private = NULL;
b16a5db0ccd159 Kairui Song 2024-01-03  912  	}
b16a5db0ccd159 Kairui Song 2024-01-03  913  
b16a5db0ccd159 Kairui Song 2024-01-03  914  	return folio;
b16a5db0ccd159 Kairui Song 2024-01-03  915  }
b16a5db0ccd159 Kairui Song 2024-01-03  916
diff mbox series

Patch

diff --git a/mm/shmem.c b/mm/shmem.c
index 928aa2304932..9da9f7a0e620 100644
--- a/mm/shmem.c
+++ b/mm/shmem.c
@@ -1872,7 +1872,7 @@  static int shmem_swapin_folio(struct inode *inode, pgoff_t index,
 	}
 
 	/* Look it up and read it in.. */
-	folio = swap_cache_get_folio(swap, NULL, 0);
+	folio = swap_cache_get_folio(swap, NULL, 0, NULL);
 	if (!folio) {
 		/* Or update major stats only when swapin succeeds?? */
 		if (fault_type) {
diff --git a/mm/swap.h b/mm/swap.h
index 1f4cdb324bf0..9180411afcfe 100644
--- a/mm/swap.h
+++ b/mm/swap.h
@@ -58,7 +58,8 @@  void delete_from_swap_cache(struct folio *folio);
 void clear_shadow_from_swap_cache(int type, unsigned long begin,
 				  unsigned long end);
 struct folio *swap_cache_get_folio(swp_entry_t entry,
-		struct vm_area_struct *vma, unsigned long addr);
+		struct vm_area_struct *vma, unsigned long addr,
+		void **shadowp);
 struct folio *filemap_get_incore_folio(struct address_space *mapping,
 		pgoff_t index);
 
diff --git a/mm/swap_state.c b/mm/swap_state.c
index f6f1e6f5d782..21badd4f0fc7 100644
--- a/mm/swap_state.c
+++ b/mm/swap_state.c
@@ -335,12 +335,18 @@  static inline bool swap_use_vma_readahead(void)
  * Caller must lock the swap device or hold a reference to keep it valid.
  */
 struct folio *swap_cache_get_folio(swp_entry_t entry,
-		struct vm_area_struct *vma, unsigned long addr)
+		struct vm_area_struct *vma, unsigned long addr, void **shadowp)
 {
 	struct folio *folio;
 
-	folio = filemap_get_folio(swap_address_space(entry), swp_offset(entry));
-	if (!IS_ERR(folio)) {
+	folio = filemap_get_entry(swap_address_space(entry), swp_offset(entry));
+	if (xa_is_value(folio)) {
+		if (shadowp)
+			*shadowp = folio;
+		return NULL;
+	}
+
+	if (folio) {
 		bool vma_ra = swap_use_vma_readahead();
 		bool readahead;
 
@@ -370,8 +376,6 @@  struct folio *swap_cache_get_folio(swp_entry_t entry,
 			if (!vma || !vma_ra)
 				atomic_inc(&swapin_readahead_hits);
 		}
-	} else {
-		folio = NULL;
 	}
 
 	return folio;
@@ -876,11 +880,10 @@  static struct folio *swap_vma_readahead(swp_entry_t targ_entry, gfp_t gfp_mask,
  * in.
  */
 static struct folio *swapin_direct(swp_entry_t entry, gfp_t gfp_mask,
-				  struct vm_fault *vmf)
+				  struct vm_fault *vmf, void *shadow)
 {
 	struct vm_area_struct *vma = vmf->vma;
 	struct folio *folio;
-	void *shadow = NULL;
 
 	/* skip swapcache */
 	folio = vma_alloc_folio(GFP_HIGHUSER_MOVABLE, 0,
@@ -897,7 +900,6 @@  static struct folio *swapin_direct(swp_entry_t entry, gfp_t gfp_mask,
 
 		mem_cgroup_swapin_uncharge_swap(entry);
 
-		shadow = get_shadow_from_swap_cache(entry);
 		if (shadow)
 			workingset_refault(folio, shadow);
 
@@ -931,17 +933,18 @@  struct folio *swapin_entry(swp_entry_t entry, gfp_t gfp_mask,
 {
 	enum swap_cache_result cache_result;
 	struct mempolicy *mpol;
+	void *shadow = NULL;
 	struct folio *folio;
 	pgoff_t ilx;
 
-	folio = swap_cache_get_folio(entry, vmf->vma, vmf->address);
+	folio = swap_cache_get_folio(entry, vmf->vma, vmf->address, &shadow);
 	if (folio) {
 		cache_result = SWAP_CACHE_HIT;
 		goto done;
 	}
 
 	if (swap_use_no_readahead(swp_swap_info(entry), entry)) {
-		folio = swapin_direct(entry, gfp_mask, vmf);
+		folio = swapin_direct(entry, gfp_mask, vmf, shadow);
 		cache_result = SWAP_CACHE_BYPASS;
 	} else {
 		mpol = get_vma_policy(vmf->vma, vmf->address, 0, &ilx);
@@ -952,7 +955,6 @@  struct folio *swapin_entry(swp_entry_t entry, gfp_t gfp_mask,
 		mpol_cond_put(mpol);
 		cache_result = SWAP_CACHE_MISS;
 	}
-
 done:
 	if (result)
 		*result = cache_result;