Re: [PATCH 3/3] Add inode table initialization code into Ext4

[Peng Tao <bergwolf@gmail.com>]

Hi, all,

On Sat, Aug 21, 2010 at 1:51 AM, Lukas Czerner <lczerner@redhat.com> wrote:
> When lazy_itable_init extended option is passed to mke2fs, it
> considerably speed up filesystem creation because inode tables are left
> uninitialized, thus contains some old data. When this fs is mounted
> filesystem code should initialize (zero out) uninitialized inode table.
> So far this code was missing for ext4 and this patch adds this feature.
>
> When file system is mounted with "inititable" mount option, new thread
> (called itableinitd) is created. This thread walks through allocation
> groups searching for the group with not yet initialized inode table.
> When such a group is found it write zeroes through whole inode table and
> put itself into sleep for defined number of seconds to not disturb other
> ongoing I/O. This is repeated until it walks through every allocation group
> then the iitableinitd thread is stopped.
This will slow down e2fsck speed that is gained from uninitialized
italbe. Am I missing something? What about having another block group
flag to tell itable that is just zeroed but not used, from itable that
is already in use?


-- 
Thanks,
-Bergwolf