Hi Zi Yan,
On Tue, Feb 13, 2024 at 04:55:13PM -0500, Zi Yan wrote:
> From: Zi Yan <ziy@xxxxxxxxxx>
>
> Hi all,
>
> File folio supports any order and multi-size THP is upstreamed[1], so both
> file and anonymous folios can be >0 order. Currently, split_huge_page()
> only splits a huge page to order-0 pages, but splitting to orders higher than
> 0 is going to better utilize large folios. In addition, Large Block
> Sizes in XFS support would benefit from it[2]. This patchset adds support for
> splitting a large folio to any lower order folios and uses it during file
> folio truncate operations.
I added your patches on top of my patches, but removed patch 6 and I
added this instead:
diff --git a/mm/truncate.c b/mm/truncate.c
index 725b150e47ac..dd07e2e327a8 100644
--- a/mm/truncate.c
+++ b/mm/truncate.c
@@ -239,7 +239,8 @@ bool truncate_inode_partial_folio(struct folio *folio, loff_t start, loff_t end)
folio_invalidate(folio, offset, length);
if (!folio_test_large(folio))
return true;
- if (split_folio(folio) == 0)
+ if (split_folio_to_order(folio,
+ mapping_min_folio_order(folio->mapping)) == 0)
return true;
if (folio_test_dirty(folio))
return false;
I ran genric/476 fstest[1] with SOAK_DURATION set to 360 seconds. This
test uses fstress to do a lot of writes, truncate operations, etc. I ran
this on XFS with **64k block size on a 4k page size system**.
I recorded the vm event for split page and this was the result I got:
Before your patches:
root@debian:~/xfstests# cat /proc/vmstat | grep split
thp_split_page 0
thp_split_page_failed 5819
After your patches:
root@debian:~/xfstests# cat /proc/vmstat | grep split
thp_split_page 5846
thp_split_page_failed 20
Your patch series definitely helps with splitting the folios while still
maintaining the min_folio_order that LBS requires.
We are still discussing how to quantify this benefit in terms of some
metric with this support. If you have some ideas here, let me know.
I will run the whole xfstests tonight to check for any regressions.
--
Pankaj
[1] https://github.com/kdave/xfstests/blob/master/tests/generic/476
