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Subject: Re: Linux patch that speeds up fat writing on usb disks
From: Brian King (brking_at_charter.net)
Date: 2003-04-24


I used to have this problem where the first write would take forever
(minutes). Since I reformatted the drive with a 32K cluster size,
however, the first write happens very fast. So fast, in fact, that the
first time I wrote to the new drive I figured I forgot to mount the
drive;) Is this a problem that presents itself over time from your
experience, meaning am I going to eventually hit this, or not? I'm
currently compiling a new kernel and added your patch so it, but since
things are working well right now I doubt I will be able to notice a
difference...

-Brian

Björn Stenberg wrote:
> Hi all.
>
> This is not really Rockbox related, but might be of interest to some of you.
>
> I have written a patch for the linux kernel that addresses a shortcoming in the linux fat filesystem driver. The fat driver starts searching for free clusters at the beginning of the partition, instead of using the hint that is available in the file system on disk. This can cause a delay of several minutes for the first write after mount if the disk is connected over a slow link such as usb 1.1.
>
> My patch changes the fat driver to use the hint, and thereby eliminates much of the searching. The first-write delay is now typically less than a second.
>
> The patch is available for linux 2.4.20 and 2.5.68, although since this code is rarely changed the patch will most likely apply on older versions too (such as 2.4.18 that is used in redhat 8.0).
>
> The patches are:
> http://bjorn.haxx.se/isd200/fat-2.4.20.patch
> http://bjorn.haxx.se/isd200/fat-2.5.68.patch
>
> I have submitted these to the linux-kernel mailing list. Time will tell if/when this will be included in the mainline kernel.
>



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