Re: [Linux-NTFS Forum: Usage Problems] RE: Large files - slow

[Moving a discussion that started on the forum to the mailing list.
Both because the discussion is now more technical, and because I
attached a file]

On 7/24/06, AntonA wrote:
> I mean yes, the runlist lookups are pretty inneficient but they are not
> _that_ inefficient and it should not cause such slowdown.  Same for the
> allocator it should not make a difference like this...

After profiling ntfs-3g-20070714, the problem is actually building the
runlist (profiling output attached).

Anyone interested in picking up the glove?

> For comparison using the kernel ntfs driver (Linux) and doing just a dd
> like so:
>
> date && time dd if=/dev/zero of=test-big-file count=1 bs=1G && date
>
> Gives me:
>
> Mon Jul 24 19:49:58 BST 2006
> 1+0 records in
> 1+0 records out
> 1073741824 bytes (1.1 GB) copied, 27.2384 seconds, 39.4 MB/s
>
> real    0m27.242s
> user    0m0.000s
> sys     0m7.460s
> Mon Jul 24 19:50:25 BST 2006
>
> So it took only 27 seconds...

Unless the kernel driver is not creating sparse files, this is not a
good comparison. ntfs-3g on my laptop did the same micro-benchmark in
66 seconds. The output file was indeed 1GB, but took on disk 0 bytes
(not counting metadata).

For comparison, coping a large file from one ntfs partition mounted
using the kernel driver to another ntfs partition mounted using
ntfs-3g copied ~142MB in 5:19 minutes. (actual size on disk: 134MB):
real    5m18.255s
user    0m0.028s
sys     0m0.728s

--
Yuval Fledel

ntfs3g-profile.txt.bz2
Description: BZip2 compressed data

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