Re: [PATCH v2 0/7] Create large folios in iomap buffered write path

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Hi,

> Commit ebb7fb1557b1 limited the length of ioend chains to 4096 entries
> to improve worst-case latency.  Unfortunately, this had the effect of
> limiting the performance of:
> 
> fio -name write-bandwidth -rw=write -bs=1024Ki -size=32Gi -runtime=30 \
>         -iodepth 1 -ioengine sync -zero_buffers=1 -direct=0 -end_fsync=1 \
>         -numjobs=4 -directory=/mnt/test
> 
> The problem ends up being lock contention on the i_pages spinlock as we
> clear the writeback bit on each folio (and propagate that up through
> the tree).  By using larger folios, we decrease the number of folios
> to be processed by a factor of 256 for this benchmark, eliminating the
> lock contention.
> 
> It's also the right thing to do.  This is a project that has been on
> the back burner for years, it just hasn't been important enough to do
> before now.
> 
> I think it's probably best if this goes through the iomap tree since
> the changes outside iomap are either to the page cache or they're
> trivial.
> 
> v2:
>  - Fix misplaced semicolon
>  - Rename fgp_order to fgp_set_order
>  - Rename FGP_ORDER to FGP_GET_ORDER
>  - Add fgp_t
>  - Update the documentation for ->release_folio
>  - Fix iomap_invalidate_folio()
>  - Update iomap_release_folio()

It works well based on 6.4-rc4 here.
fio write bandwidth: about 8000MiB/s

And I tried to backport it to 6.1.y, it works well too.
1) 8 patches are selected as depency.
    d7b64041164c :Dave Chinner: iomap: write iomap validity checks

    7a70a5085ed0 :Andreas Gruenbacher: iomap: Add __iomap_put_folio helper
    80baab88bb93 :Andreas Gruenbacher: iomap/gfs2: Unlock and put folio in page_done handler
    40405dddd98a :Andreas Gruenbacher: iomap: Rename page_done handler to put_folio

    98321b5139f9 :Andreas Gruenbacher: iomap: Add iomap_get_folio helper

    9060bc4d3aca :Andreas Gruenbacher: iomap/gfs2: Get page in page_prepare handler
    07c22b56685d :Andreas Gruenbacher: iomap: Add __iomap_get_folio helper
    c82abc239464 :Andreas Gruenbacher: iomap: Rename page_prepare handler to get_folio

2) patch 4/5/6 are rebased (see attachment files)

better backport are welcome.

Best Regards
Wang Yugui (wangyugui@xxxxxxxxxxxx)
2023/06/04



> Matthew Wilcox (Oracle) (7):
>   iomap: Remove large folio handling in iomap_invalidate_folio()
>   doc: Correct the description of ->release_folio
>   iomap: Remove unnecessary test from iomap_release_folio()
>   filemap: Add fgp_t typedef
>   filemap: Allow __filemap_get_folio to allocate large folios
>   iomap: Create large folios in the buffered write path
>   iomap: Copy larger chunks from userspace
> 
>  Documentation/filesystems/locking.rst | 14 ++++--
>  fs/btrfs/file.c                       |  6 +--
>  fs/f2fs/compress.c                    |  2 +-
>  fs/f2fs/f2fs.h                        |  2 +-
>  fs/gfs2/bmap.c                        |  2 +-
>  fs/iomap/buffered-io.c                | 43 ++++++++--------
>  include/linux/iomap.h                 |  2 +-
>  include/linux/pagemap.h               | 71 ++++++++++++++++++++++-----
>  mm/filemap.c                          | 61 ++++++++++++-----------
>  mm/folio-compat.c                     |  2 +-
>  mm/readahead.c                        | 13 -----
>  11 files changed, 130 insertions(+), 88 deletions(-)
> 
> -- 
> 2.39.2

Attachment: 0006-iomap-Create-large-folios-in-the-buffered-write-path.patch
Description: Binary data

Attachment: 0004-filemap-Add-fgp_t-typedef.patch
Description: Binary data

Attachment: 0005-filemap-Allow-__filemap_get_folio-to-allocate-large-.patch
Description: Binary data

Attachment: 0006-iomap-Create-large-folios-in-the-buffered-write-path.patch
Description: Binary data


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