mm/page_io: count submission time as thrashing delay for delayacct

Once upon a time, we only support accounting thrashing of page cache.
Then Joonsoo introduced workingset detection for anonymous pages and we
gained the ability to account thrashing of them[1].

Likes PSI, we count submission time as thrashing delay because when the
device is congested, or the submitting cgroup IO-throttled, submission can
be a significant part of overall IO time.

Without this patch, swap thrashing through frontswap or some block
device supporting rw_page operation isn't measured correctly.

This patch is based on "delayacct: support re-entrance detection of
thrashing accounting".

[1] commit aae466b0052e ("mm/swap: implement workingset detection for anonymous LRU")

Link: https://lkml.kernel.org/r/20220815072835.74876-1-yang.yang29@zte.com.cn
Signed-off-by: Yang Yang <yang.yang29@zte.com.cn>
Signed-off-by: CGEL ZTE <cgel.zte@gmail.com>
Reviewed-by: Ran Xiaokai <ran.xiaokai@zte.com.cn>
Reviewed-by: wangyong <wang.yong12@zte.com.cn>
Cc: Joonsoo Kim <iamjoonsoo.kim@lge.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>

diff --git a/mm/page_io.c b/mm/page_io.c
index 68d53fc27598af2a58160386b05be1760efdf259..fc6b3fb1f7c59647c05eea324c25930e6346ebe0 100644 (file)
--- a/mm/page_io.c
+++ b/mm/page_io.c
@@ -452,18 +452,21 @@ int swap_readpage(struct page *page, bool synchronous,
        struct swap_info_struct *sis = page_swap_info(page);
        bool workingset = PageWorkingset(page);
        unsigned long pflags;
+       bool in_thrashing;
 
        VM_BUG_ON_PAGE(!PageSwapCache(page) && !synchronous, page);
        VM_BUG_ON_PAGE(!PageLocked(page), page);
        VM_BUG_ON_PAGE(PageUptodate(page), page);
 
        /*
-        * Count submission time as memory stall. When the device is congested,
-        * or the submitting cgroup IO-throttled, submission can be a
-        * significant part of overall IO time.
+        * Count submission time as memory stall and delay. When the device
+        * is congested, or the submitting cgroup IO-throttled, submission
+        * can be a significant part of overall IO time.
         */
-       if (workingset)
+       if (workingset) {
+               delayacct_thrashing_start(&in_thrashing);
                psi_memstall_enter(&pflags);
+       }
        delayacct_swapin_start();
 
        if (frontswap_load(page) == 0) {
@@ -512,8 +515,10 @@ int swap_readpage(struct page *page, bool synchronous,
        bio_put(bio);
 
 out:
-       if (workingset)
+       if (workingset) {
+               delayacct_thrashing_end(&in_thrashing);
                psi_memstall_leave(&pflags);
+       }
        delayacct_swapin_end();
        return ret;
 }