Re: Syncing single filesystem (slow USB writing)

From: Andrew Morton
Date: Thu Jul 28 2005 - 22:52:02 EST

Andrey Borzenkov <arvidjaar@xxxxxxx> 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.

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