Re: vfat file system extreme fragmentation on multiprocessor

From: Lennart Sorensen
Date: Thu Sep 11 2008 - 17:09:20 EST

On Thu, Sep 11, 2008 at 12:36:24PM -0700, H. Peter Anvin wrote:
> Lennart Sorensen wrote:
> >
> >I don't think fat filesystems have any concept of reserving space for
> >expanding files. It's a pretty simple filesystem after all designed for
> >a single cpu machine with a non-multitasking OS (if you can call DOS an
> >OS). Space tends to be allocated from the start of the disk wherever
> >free space is found since otherwise you would have to go searching for
> >the free space, which isn't that efficient.
> >
> Well, you can always do that in-memory.

It still involves searching no matter where you do it. With FAT-16 that
means up to 2^16 clusters to search through. With FAT-32 even more. It
doesn't have a cluster bitmap to speed things up.

Len Sorensen
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