On 09/05/2013 02:35 AM, Theodore Ts'o wrote:

How did you gather these results?  The mbcache is only used if you are
using extended attributes, and only if the extended attributes don't
fit in the inode's extra space.

I checked aim7, and it doesn't do any extended attribute operations.
So why are you seeing differences?  Are you doing something like
deliberately using 128 byte inodes (which is not the default inode
size), and then enabling SELinux, or some such?

						- Ted

No, I did not do anything special, including changing an inode's size. I just used the profile data, which indicated mb_cache module as one of the bottleneck.  Please see below for perf data from one of th new_fserver run, which also shows some mb_cache activities.


                        |--3.51%-- __mb_cache_entry_find
                        |          mb_cache_entry_find_first
                        |          ext4_xattr_cache_find
                        |          ext4_xattr_block_set
                        |          ext4_xattr_set_handle
                        |          ext4_initxattrs
                        |          security_inode_init_security
                        |          ext4_init_security
                        |          __ext4_new_inode
                        |          ext4_create
                        |          vfs_create
                        |          lookup_open
                        |          do_last
                        |          path_openat
                        |          do_filp_open
                        |          do_sys_open
                        |          SyS_open
                        |          sys_creat
                        |          system_call
                        |          __creat_nocancel
                        |          |
                        |          |--16.67%-- 0x11fe2c0
                        |          |

Thanks,
Mak.