On 10/21/25 11:33, Jeuk Kim wrote: > > 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?
Hi Jeuk, We're using sbi->writepages to serialize large IOs, once you tuned default value from 2MB to 512KB, in Android, there are threads issue [512K, 2M) sized IOs, they will join into racing on grabbing the .writepages lock, I guess that will cause potential performance regression, right? Thanks, > > Thanks again for your help. > _______________________________________________ Linux-f2fs-devel mailing list [email protected] https://lists.sourceforge.net/lists/listinfo/linux-f2fs-devel
