On 10/16/2025 7:12 PM, Chao Yu wrote:
On 10/16/2025 1:16 PM, Jeuk Kim wrote:
From: Jeuk Kim <[email protected]>
Inline encryption derives DUN from <inode, file offset>,
so bios from different inodes can't merge. With multi-threaded
buffered O_SYNC writes where each thread writes to its own file,
4KiB-per-page LBA allocation interleaves across inodes and
causes bio split. Serialize writeback for fscrypt inline-crypto
inodes via __should_serialize_io() to keep foreground writeback
focused on one inode and avoid split.
Test: fio --name=wb_osync --rw=write --bs=1M \
--time_based=1 --runtime=60s --size=2G \
--ioengine=psync --direct=0 --sync=1 \
--numjobs=8 --thread=1 --nrfiles=1 \
--filename_format='wb_osync.$jobnum'
device: UFS
Before -
write throughput: 675MiB/s
device I/O size distribution (by count, total 1027414):
4 KiB: 923139 (89.9%)
8 KiB: 84798 (8.3%)
≥512 KiB: 453 (0.0%)
After -
write throughput: 1760MiB/s
device I/O size distribution (by count, total 231750):
4 KiB: 16904 (7.3%)
8 KiB: 72128 (31.1%)
≥512 KiB: 118900 (51.3%)
Signed-off-by: Jeuk Kim <[email protected]>
---
fs/f2fs/data.c | 2 ++
1 file changed, 2 insertions(+)
diff --git a/fs/f2fs/data.c b/fs/f2fs/data.c
index ef38e62cda8f..ae6fb435d576 100644
--- a/fs/f2fs/data.c
+++ b/fs/f2fs/data.c
@@ -3217,6 +3217,8 @@ static inline bool __should_serialize_io(struct
inode *inode,
if (f2fs_need_compress_data(inode))
return true;
+ if (fscrypt_inode_uses_inline_crypto(inode))
+ return true;
if (wbc->sync_mode != WB_SYNC_ALL)
return true;
if (get_dirty_pages(inode) >=
SM_I(F2FS_I_SB(inode))->min_seq_blocks)
Jeuk,
Can you please try tuning /sys/fs/f2fs/<dev>/min_seq_blocks to see
whether it
can achive the goal?
Thanks,
Hi Chao,
Thanks a lot for the suggestion.
I tried tuning `/sys/fs/f2fs/<dev>/min_seq_blocks` as you mentioned, and
it also achieved similar performance improvement on my setup.
Your approach looks cleaner and better than the one I proposed.
From what I see, even after reducing this value from the default (2MB)
to 512 KB on my local system, there doesn’t seem to be any noticeable
performance drop or other side effects.
Do you see any possible downsides with lowering this value that I might
have missed?
Thanks again for your help.
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