https://bugzilla.kernel.org/show_bug.cgi?id=71641 Bug ID: 71641 Summary: Unreasonable performance degradation in ext4 with full data journaling Product: File System Version: 2.5 Kernel Version: 3.4.6 Hardware: x86-64 OS: Linux Tree: Mainline Status: NEW Severity: normal Priority: P1 Component: ext4 Assignee: fs_ext4@xxxxxxxxxxxxxxxxxxxx Reporter: fredchang.tc@xxxxxxxxx Regression: No JFS provides three modes, journal, ordered and writeback. The first mode is denoted as ‘journal mode’in the following context. In the journal mode, data should be written twice, one for the journal area and the other for the client file system. If the journal area and the client file system are both located in the disk, it has at least 50% performance degradation compared to ordered mode. But what if we put the journal area in a ramdisk? I did the following tests. It shows the ext4 with full data journaling has unreasonable performance degradation even the journal area is located in the ramdisk. Test environment-- CPU: Intel(R) Xeon(R) CPU E3-1225 v3 @ 3.20GHz RAM:8GB Filesystem:Ext4 Linux version:3.4.6 RAID are composed of 6 x 1TB HD Command: time dd if=/dev/zero of= Write_File bs=1M count=51200 Volume_type ordered_mode Journal_mode degradation Single_disk 173MB/s 144MB/s 17% RAID0 937MB/s 375MB/s 60% RAID5 732MB/s 132MB/s 82% Does anyone know where the bottleneck may be? -- You are receiving this mail because: You are watching the assignee of the bug.-- To unsubscribe from this list: send the line "unsubscribe linux-ext4" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
