Re: Syncing single filesystem (slow USB writing)

[Andrew Morton <akpm@osdl.org>]

Andrey Borzenkov <arvidjaar@mail.ru> wrote:
>
> Mandrake always mounted USB sticks with sync option; it was effectively noop 
> except for a patch that implemented limited dsync semantic.
> 
> Now, when full sync support for FATis in kernel, moutning with sync became 
> real pain. Writing speed dropped from 3MB/s to 30KB/s in my case (and I am 
> not alone).

Unfortunately I think we're just going to have to live with that.  It is
right that fatfs behaves as it does, and unfortunate that some distros will
operate slowly.

For reference: how does mandrake implement this?  Just in /etc/fstab?  How
should we tell other people to fix this?

> One idea how to improve situation - continue to mount with dsync (having 
> basically old case) and do frequent sync of filesystem (this culd be started 
> as HAL callout or whatever). Unfortunately, I could not find a way to request 
> a sync (flush) of single mount point or block device. Have I missed 
> something?

It's trivial to do in-kernel but no, I'm afraid there isn't a userspace
interface for this.