Hi, I ran the fs_mark test on a single empty hard drive. After the test, the df -h results are: /dev/sdk1 917G 39G 832G 5% /ext4 /dev/sdj1 932G 53G 850G 6% /btrfs The test result for btrfs shows it ran 15 hours. Note there is no file/dir remove operation which I knew very slow compared with ext4. [root@sh679 ~]# date;/root/fs_mark -v -n 1000000 -s 4096 -k -S 1 -D 1000 -N 1000 -d /btrfs/ -t 10;date Mon Aug 11 11:32:54 PDT 2014 # /root/fs_mark -v -n 1000000 -s 4096 -k -S 1 -D 1000 -N 1000 -d /btrfs/ -t 10 # Version 3.3, 10 thread(s) starting at Mon Aug 11 11:32:54 2014 # Sync method: INBAND FSYNC: fsync() per file in write loop. # Directories: Round Robin between directories across 1000 subdirectories with 1000 files per subdirectory. # File names: 40 bytes long, (16 initial bytes of time stamp with 24 random bytes at end of name) # Files info: size 4096 bytes, written with an IO size of 16384 bytes per write # App overhead is time in microseconds spent in the test not doing file writing related system calls. # All system call times are reported in microseconds FSUse% Count Size Files/sec App Overhead CREAT (Min/Avg/Max) WRITE (Min/Avg/Max) FSYNC (Min/Avg/Max) SYNC (Min/Avg/Max) CLOSE (Min/Avg/Max) UNLINK (Min/Avg/Max) 8 10000000 4096 184.0 155517800 33 372 93743 7 16 3094 16450 54015 5420340 0 0 0 1 4 7777 0 0 0 Tue Aug 12 02:40:01 PDT 2014 For hours, the disk utilization was around 95% and cpu utilization for all 12 cores was very low and only one core showed around 26%wa. To compare with Ext4: The test for ext4 on a same model of hard drive ran 2.5 hours. [root@sh679 ~]# date;/root/fs_mark -v -n 1000000 -s 4096 -k -S 1 -D 1000 -N 1000 -d /ext4/ -t 10;date Fri Aug 8 17:13:56 PDT 2014 # /root/fs_mark -v -n 1000000 -s 4096 -k -S 1 -D 1000 -N 1000 -d /ext4/ -t 10 # Version 3.3, 10 thread(s) starting at Fri Aug 8 17:13:56 2014 # Sync method: INBAND FSYNC: fsync() per file in write loop. # Directories: Round Robin between directories across 1000 subdirectories with 1000 files per subdirectory. # File names: 40 bytes long, (16 initial bytes of time stamp with 24 random bytes at end of name) # Files info: size 4096 bytes, written with an IO size of 16384 bytes per write # App overhead is time in microseconds spent in the test not doing file writing related system calls. # All system call times are reported in microseconds. FSUse% Count Size Files/sec App Overhead CREAT (Min/Avg/Max) WRITE (Min/Avg/Max) FSYNC (Min/Avg/Max) SYNC (Min/Avg/Max) CLOSE (Min/Avg/Max) UNLINK (Min/Avg/Max) 9 10000000 4096 105.0 156950153 19 449 1741759 6 15 2069984 32368 94751 2044364 0 0 0 1 4 4149 0 0 0 Sat Aug 9 19:41:14 PDT 2014 Is it a known issue with btrfs or do I need to adjust the default parameters for btrfs (I remember use the default to make btrfs)? Mount command shows: /dev/sdk1 on /ext4 type ext4 (rw,relatime,seclabel,data=ordered) /dev/sdj1 on /btrfs type btrfs (rw,relatime,seclabel,nospace_cache) Thanks Ming -- To unsubscribe from this list: send the line "unsubscribe linux-btrfs" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html