This RFC PATCH series adds support for large folio buffered writes
to regular readable and writable files in f2fs with exception of
atomic/compressed/inlined files.
Since adapting page writeback to support large folios is relatively complex,
it is not included in this series.
I ran simple `dd` tests on a Pixel 6 device.
During the tests, dirty page writeback was temporarily disabled.
---------------------------------------------------------------------------------
Test:
echo 100 > /proc/sys/vm/dirty_ratio
echo 100 > /proc/sys/vm/dirty_background_ratio
echo 0 > /proc/sys/vm/dirty_writeback_centisecs
echo 8640000 > /proc/sys/vm/dirty_expire_centisecs
Before large folio enable:
oriole:/data # dd if=/dev/zero of=lf.c bs=2M count=500
500+0 records in
500+0 records out
1048576000 bytes (0.9 G) copied, 0.815 s, 1.1 G/s
After large folio enable:
oriole:/data # dd if=/dev/zero of=lf.c bs=2M count=500
500+0 records in
500+0 records out
1048576000 bytes (0.9 G) copied, 0.330 s, 2.9 G/s
---------------------------------------------------------------------------------
Note:
- bs=2M means always allocating the largest folio order in buffered write,
so it represents a theoretical maximum write performance.
- Because large folio support can only be enabled for files via f2fs_iget,
it may be more convenient for testing to create a large file first and then
immediately reboot the device so that the inode is reloaded.
**Discussion:**
I would like to add fault injection to `f2fs_write_end` to simulate short
writes
(copied != len).
However, I am concerned that directly adding time_to_inject inside
f2fs_write_end
and returning 0 may cause generic_perform_write to loop forever during testing.
Better ideas are appreciated.
Thanks.
---
Nanzhe Zhao (5):
f2fs: Move f2fs_folio_state to f2fs.h
f2fs: Introduce f2fs_inode_may_use_large_folio
f2fs: Preallocate partial-write blocks for large-folio write
f2fs: Support large folios buffered write
f2fs: Make folio->private flags work with folio state
fs/f2fs/data.c | 226 ++++++++++++++++++++++++++++++++++++++++++++----
fs/f2fs/f2fs.h | 58 ++++++++++---
fs/f2fs/file.c | 21 +++--
fs/f2fs/inode.c | 3 +-
4 files changed, 272 insertions(+), 36 deletions(-)
base-commit: bc367775f60214312befa33f101b31fe74bba48a
--
2.34.1
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