This commit 0e3d2a6313(ext4: Fix async commit mode to be safe by using
a barrier) show that using journal_async_commit feature has a 50%
performance improvement. But I tested in SUSE Linux Enterprise Server
11 SP3(linux kernel 3.0.93) and Red Hat Enterprise linux 6.4(linux
kernel 2.6.32), the result show this feature has no performance
improvement.
My test command:
mount /dev/sdb /mnt/sdb
./fs_mark -d /mnt/sdb/ -s 10240 -n 1000
umount
mount /dev/sdb /mnt/sdb -o journal_async_commit
./fs_mark -d /mnt/sdb/ -s 10240 -n 1000
umount
My test result:
FSUse% Count Size Files/sec App Overhead
6 1000 10240 42.1 10671
vs.
-o journal_async_commit
FSUse% Count Size Files/sec App Overhead
6 1000 10240 63.9 10625
Superblock info(-o journal_async_commit):
Filesystem features: has_journal ext_attr resize_inode dir_index
filetype needs_recovery extent flex_bg sparse_super large_file
huge_file
uninit_bg dir_nlink extra_isize
Block size: 4096
Journal backup: inode blocks
Journal features: journal_checksum journal_async_commit
Journal size: 128M
Journal length: 32768
Journal sequence: 0x000017a6
Journal start: 1
Am I missing something?
---Alex
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