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mm/filemap: don't decrease mmap_miss when folio has workingset flag

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If there are too many folios that are recently evicted in a file, then
they will probably continue to be evicted.  In such situation, there is no
positive effect to read-ahead this file since it is only a waste of IO.

The mmap_miss is increased in do_sync_mmap_readahead() and decreased in
both do_async_mmap_readahead() and filemap_map_pages().  In order to skip
read-ahead in above scenario, the mmap_miss have to increased exceed
MMAP_LOTSAMISS.  This can be done by stop decreased mmap_miss when folio
has workingset flag.  The async path is not to care because in above
scenario, it's hard to run into the async path.

[liushixin2@huawei.com: add comments]
  Link: https://lkml.kernel.org/r/20240326065026.1910584-1-liushixin2@huawei.com
Link: https://lkml.kernel.org/r/20240322093555.226789-3-liushixin2@huawei.com
Signed-off-by: Liu Shixin <liushixin2@huawei.com>
Reviewed-by: Jan Kara <jack@suse.cz>
Cc: Al Viro <viro@ZenIV.linux.org.uk>
Cc: Christian Brauner <brauner@kernel.org>
Cc: Jinjiang Tu <tujinjiang@huawei.com>
Cc: Matthew Wilcox (Oracle) <willy@infradead.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
This commit is contained in:
Liu Shixin 2024-03-22 17:35:55 +08:00 committed by Andrew Morton
parent 0fd44ab213
commit 5c46d5319b
1 changed files with 12 additions and 2 deletions
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14
mm/filemap.c
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@ -3492,7 +3492,15 @@ static vm_fault_t filemap_map_folio_range(struct vm_fault *vmf,
if (PageHWPoison(page + count))
goto skip;
(*mmap_miss)++;
/*
* If there are too many folios that are recently evicted
* in a file, they will probably continue to be evicted.
* In such situation, read-ahead is only a waste of IO.
* Don't decrease mmap_miss in this scenario to make sure
* we can stop read-ahead.
*/
if (!folio_test_workingset(folio))
(*mmap_miss)++;
/*
* NOTE: If there're PTE markers, we'll leave them to be
@ -3541,7 +3549,9 @@ static vm_fault_t filemap_map_order0_folio(struct vm_fault *vmf,
if (PageHWPoison(page))
return ret;
(*mmap_miss)++;
/* See comment of filemap_map_folio_range() */
if (!folio_test_workingset(folio))
(*mmap_miss)++;
/*
* NOTE: If there're PTE markers, we'll leave them to be