diff mbox series

mm/vmstat: add event for ksm swapping in copy

Message ID 20220112115110.669160-1-yang.yang29@zte.com.cn (mailing list archive)
State New
Headers show
Series mm/vmstat: add event for ksm swapping in copy | expand

Commit Message

CGEL Jan. 12, 2022, 11:51 a.m. UTC 
From: Yang Yang <yang.yang29@zte.com.cn>

When faults in from swap what used to be a KSM page and that page
had been swapped in before, system has to make a copy, and leaves
remerging the pages to a later pass of ksmd.

That is not good for performace, we'd better to reduce this kind
of copy. There are some ways to reduce it, for example lessen
swappiness or madvise(, , MADV_MERGEABLE) range. So add this
event to support doing this tuning. Just like this patch:
"mm, THP, swap: add THP swapping out fallback counting".

Signed-off-by: Yang Yang <yang.yang29@zte.com.cn>
Reviewed-by: Ran Xiaokai <ran.xiaokai@zte.com.cn>
---
 include/linux/vm_event_item.h | 3 +++
 mm/ksm.c                      | 1 +
 mm/vmstat.c                   | 3 +++
 3 files changed, 7 insertions(+)

Comments

kernel test robot Jan. 12, 2022, 3:58 p.m. UTC | #1 
Hi,

Thank you for the patch! Yet something to improve:

[auto build test ERROR on hnaz-mm/master]

url:    https://github.com/0day-ci/linux/commits/cgel-zte-gmail-com/mm-vmstat-add-event-for-ksm-swapping-in-copy/20220112-195303
base:   https://github.com/hnaz/linux-mm master
config: alpha-buildonly-randconfig-r004-20220112 (https://download.01.org/0day-ci/archive/20220112/202201122306.EC6LSwot-lkp@intel.com/config)
compiler: alpha-linux-gcc (GCC) 11.2.0
reproduce (this is a W=1 build):
        wget https://raw.githubusercontent.com/intel/lkp-tests/master/sbin/make.cross -O ~/bin/make.cross
        chmod +x ~/bin/make.cross
        # https://github.com/0day-ci/linux/commit/56a4520e557228d8383f27b6aef54b2f931a0588
        git remote add linux-review https://github.com/0day-ci/linux
        git fetch --no-tags linux-review cgel-zte-gmail-com/mm-vmstat-add-event-for-ksm-swapping-in-copy/20220112-195303
        git checkout 56a4520e557228d8383f27b6aef54b2f931a0588
        # save the config file to linux build tree
        mkdir build_dir
        COMPILER_INSTALL_PATH=$HOME/0day COMPILER=gcc-11.2.0 make.cross O=build_dir ARCH=alpha SHELL=/bin/bash

If you fix the issue, kindly add following tag as appropriate
Reported-by: kernel test robot <lkp@intel.com>

All errors (new ones prefixed by >>):

   mm/ksm.c: In function 'ksm_might_need_to_copy':
>> mm/ksm.c:2597:32: error: 'KSM_SWPIN_COPY' undeclared (first use in this function)
    2597 |                 count_vm_event(KSM_SWPIN_COPY);
         |                                ^~~~~~~~~~~~~~
   mm/ksm.c:2597:32: note: each undeclared identifier is reported only once for each function it appears in


vim +/KSM_SWPIN_COPY +2597 mm/ksm.c

  2565	
  2566	struct page *ksm_might_need_to_copy(struct page *page,
  2567				struct vm_area_struct *vma, unsigned long address)
  2568	{
  2569		struct anon_vma *anon_vma = page_anon_vma(page);
  2570		struct page *new_page;
  2571	
  2572		if (PageKsm(page)) {
  2573			if (page_stable_node(page) &&
  2574			    !(ksm_run & KSM_RUN_UNMERGE))
  2575				return page;	/* no need to copy it */
  2576		} else if (!anon_vma) {
  2577			return page;		/* no need to copy it */
  2578		} else if (anon_vma->root == vma->anon_vma->root &&
  2579			 page->index == linear_page_index(vma, address)) {
  2580			return page;		/* still no need to copy it */
  2581		}
  2582		if (!PageUptodate(page))
  2583			return page;		/* let do_swap_page report the error */
  2584	
  2585		new_page = alloc_page_vma(GFP_HIGHUSER_MOVABLE, vma, address);
  2586		if (new_page &&
  2587		    mem_cgroup_charge(page_folio(new_page), vma->vm_mm, GFP_KERNEL)) {
  2588			put_page(new_page);
  2589			new_page = NULL;
  2590		}
  2591		if (new_page) {
  2592			copy_user_highpage(new_page, page, address, vma);
  2593	
  2594			SetPageDirty(new_page);
  2595			__SetPageUptodate(new_page);
  2596			__SetPageLocked(new_page);
> 2597			count_vm_event(KSM_SWPIN_COPY);
  2598		}
  2599	
  2600		return new_page;
  2601	}
  2602	

---
0-DAY CI Kernel Test Service, Intel Corporation
https://lists.01.org/hyperkitty/list/kbuild-all@lists.01.org
diff mbox series

Patch

diff --git a/include/linux/vm_event_item.h b/include/linux/vm_event_item.h
index 7b2363388bfa..16a0a4fd000b 100644
--- a/include/linux/vm_event_item.h
+++ b/include/linux/vm_event_item.h
@@ -129,6 +129,9 @@  enum vm_event_item { PGPGIN, PGPGOUT, PSWPIN, PSWPOUT,
 #ifdef CONFIG_SWAP
 		SWAP_RA,
 		SWAP_RA_HIT,
+#ifdef CONFIG_KSM
+		KSM_SWPIN_COPY,
+#endif
 #endif
 #ifdef CONFIG_X86
 		DIRECT_MAP_LEVEL2_SPLIT,
diff --git a/mm/ksm.c b/mm/ksm.c
index c20bd4d9a0d9..b6b382fde3d4 100644
--- a/mm/ksm.c
+++ b/mm/ksm.c
@@ -2595,6 +2595,7 @@  struct page *ksm_might_need_to_copy(struct page *page,
 		SetPageDirty(new_page);
 		__SetPageUptodate(new_page);
 		__SetPageLocked(new_page);
+		count_vm_event(KSM_SWPIN_COPY);
 	}
 
 	return new_page;
diff --git a/mm/vmstat.c b/mm/vmstat.c
index 4057372745d0..d2b9f27eb1c4 100644
--- a/mm/vmstat.c
+++ b/mm/vmstat.c
@@ -1385,6 +1385,9 @@  const char * const vmstat_text[] = {
 #ifdef CONFIG_SWAP
 	"swap_ra",
 	"swap_ra_hit",
+#ifdef CONFIG_KSM
+	"ksm_swpin_copy",
+#endif
 #endif
 #ifdef CONFIG_X86
 	"direct_map_level2_splits",