Hi,
There were some feedbacks about coping many files is slow. We took a look
and improved the speed typically by 50-1000%. It's not a typo. The higher
value we have measured was indeed one thousand percentage.
Here it is what was going on.
When applications wrote files and the file size were not a multiply of the
block size (over 99.995% of all cases) then when ntfs-3g made a write
request to the Linux kernel, the kernel sought to the relevant disk sector
and read the remaining bytes to fill the end of the buffer, instead doing
the job asynchronously. This has caused disk head seek storms and very
inefficient write performance (it can be reproduce with other file systems
as well). We don't know yet if this is a bug or feature in the Linux
kernel.
This release candinate aims to solved the above problem, hereby greatly
improve related performances.
For example unpacking the Linux kernel source tree (21,000+ files) is
usually 3-6 times faster now, depending on the hardware.
Please note that this fix can't decrease the CPU usage. In fact, just the
opposite. Beforehand the time was spent waiting for the slow disk I/O. By
eliminating most of the disk seeks now, the CPU can achieve more useful
work which will result higher CPU usage. Of course that will be improved
too at some point in the future.
The benchmarks are done on Linux, the performance impact is not known on
other OSes but it should not be worse.
This speed enhancement wouldn't have happened without David Fox's
continuous help from week after week. Thank you David!
Concurrent write performance is improved as well, moreover the performance
of writing multi-GB size files, especially after the creation of thousands
of other files. This only helps if the disk space is defragmented (file
level defragmention is not enough). As far as we know, there is no free
utility which could do this, so we plan to release one in the near future.
The release candidate is available at
http://ntfs-3g.org/
If no problem will be reported then the next stable release will be made
earliest on late Wednesday, UTC. Please test intensively. Here are some
help how one can do it without Windows and without [using] existing NTFS
partitions,
http://ntfs-3g.org/quality.html#howtotest
Thank you for your attention and support,
Szabolcs
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