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SubjectRe: [PATCH 0/7] OMFS filesystem version 3

On Sun, 13 Apr 2008, Bob Copeland wrote:

> I don't have hard numbers, but anecdotally my FUSE version is quite
> a bit less performant. That's no criticism of FUSE - I just haven't
> put the time into optimizing and adding various caches.

Thankfully you need none, it's already there by FUSE and the kernel. The
trick is exactly that you can have the kernel performance and the left is
moved to user space with typically negligible performance overhead which is
usually well compensated with faster delivered new features and bug fixes.

The completely unoptimized ntfs-3g read/write saturates my USB disks with
25-30 MB/sec using 8% (read), 35% (write) CPU time on a 2.5 GHz Core 2 Duo
with cold caches.

If you have the free hot caches then it performs the same as in-kernel
file systems, user space isn't involved at all.

I noticed that the OMFS kernel driver supports only the USB interface and
the FUSE one both the network and the USB one. Isn't it possible that you
compared the performance using the USB with the kernel vs the much slower
and lower latency network with FUSE? You should compare performances using
only the USB interface in both cases.

If you did use the USB interface with FUSE then what exactly do you mean by
"quite a bit less performance" in numbers and workloads? What you did, how
long it took using what CPU?

Thanks,
Szaka

--
NTFS-3G: http://ntfs-3g.org


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