Re: [PATCH] ubifs: Introduce a mount option of force_atime.

[Richard Weinberger <richard@nod.at>]

Am 08.06.2015 um 10:27 schrieb Dongsheng Yang:
> Currently, ubifs does not support access time anyway. I understand
> that there is a overhead to update inode in each access from user.
> 
> But for the following two reasons, I think we can make it optional
> to user.
> 
> (1). More and more flash storage in server are trying to use ubifs,
> it is not only for a device such as mobile phone any more, we want
> to use it in more and more generic way. Then we need to compete
> with some other main filesystems. From this point, access time is
> necessary to us, at least as a choice to user currently.

Do you have a reference? I know that modern servers use a lot of SSDs
which use internally NAND (mostly MLC and TLC).
But which systems use RAW NAND where they would care about the atime?

> (2). The default mount option about atime is relatime currently,
> it's much relaxy compared with strictatime. Then we don't update
> the inode in any accessing. So the overhead is not too much.
> It's really acceptable.

Did you consider ext4's lazytime? I can think of something like that
for UBIFS too.

Thanks,
//richard