Re: [PATCH v3 0/2] ext4: increase mbcache scalability

[Thavatchai Makphaibulchoke]

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.

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