Help with disk copy speed.

QNX Newsgroups (Archives) qdn.public.qnx4
#1

I am starting to track down a reported copy speed problem.

The scenario is that files copied with NT or Linux report (via time), a
real time transfer of between 10 and 20 MB/s and QNX 4.24 & 4.25 report
about 2MB/s

We have swappable EIDE drives (which, by the way, is a great way to
change OS’s on a computer about $15-$20. Watch out there are several
physical formats, so pick
one, tell others and stay with it.)

Fsys.eide is the driver. I am setting up to get some real numbers under
controlled
conditions, but thought I’d ask now.

Disks say they’re capable of 60MB/s

Thanks, for any help,
Merle
Quantum Magnetics.

#2

I’m not an expert in this at all, but my experience with data access speeds
with OS’s is that you can’t trust what they say. They all handle data
access in different ways. Some will put data into buffers before being
written, others will not block on a write() call and make you THINK you got
better data transfers. This is all from a software point of view by the
way. I wrote a program to try to benchmark data transfer rates in QNX,
Windows, BeOS, and Linux, and realized afterward that it wasn’t going to
give me the information I wanted.

Ron

#3

God have merci, please use BIGGER FONTS…

“Merle J. Ebbert” <mebbert@qm.com> wrote in message news:3B37694B.A1E29100@qm.com…
I am starting to track down a reported copy speed problem.
The scenario is that files copied with NT or Linux report (via time), a real time transfer of between 10 and 20 MB/s and QNX 4.24 & 4.25 report about 2MB/s


Fsys.eide do not use DMA, hence performance is fairly bad. There isn’t much you can do about it. You could make sure your bios set the hardware to PIO mode 4 (or 5) but that won’t make much difference.
We have swappable EIDE drives (which, by the way, is a great way to change OS’s on a computer about $15-$20. Watch out there are several physical formats, so pick
one, tell others and stay with it.)

Fsys.eide is the driver. I am setting up to get some real numbers under controlled
conditions, but thought I’d ask now.

Disks say they’re capable of 60MB/s

Thanks, for any help,
Merle
Quantum Magnetics.

#4

What speed computer are you running this on? I don’t think
the QNX 4 EIDE driver ever supported DMA, which means that
it will probably be slower than an OS that does. 2MB/s
seems a little beit low to me. As to the 20 and 20/MB/sec
speeds, they seem quite questionable. A 10,000RPM drive
will do I/O at 10, but not 20. A 7200rpm drive probably won’t
do either. You are talking about a copy which takes double
the number of I/O’s. so it is likely that your test is
fooling you in some way.


Previously, Merle J. Ebbert wrote in qdn.public.qnx4:

I am starting to track down a reported copy speed problem.

The scenario is that files copied with NT or Linux report (via time), a
real time transfer of between 10 and 20 MB/s and QNX 4.24 & 4.25 report
about 2MB/s

We have swappable EIDE drives (which, by the way, is a great way to
change OS’s on a computer about $15-$20. Watch out there are several
physical formats, so pick
one, tell others and stay with it.)

Fsys.eide is the driver. I am setting up to get some real numbers under
controlled
conditions, but thought I’d ask now.

Disks say they’re capable of 60MB/s

Thanks, for any help,
Merle
Quantum Magnetics.

–
Mitchell Schoenbrun --------- maschoen@pobox.com

#5

Amen. Or just use plain text and we can read your posts in our own favorite
font and size.


“Mario Charest” <mcharest@deletezinformatic.com> wrote in message
news:9h7pvo$nb9$1@inn.qnx.com…

God have merci, please use BIGGER FONTS…

#6

I third the motion; I prefer that you use what I call “Old Guy fonts”. TIA

“Bill Caroselli @ Q-TPS” wrote:

Amen. Or just use plain text and we can read your posts in our own favorite
font and size.

“Mario Charest” <> mcharest@deletezinformatic.com> > wrote in message
news:9h7pvo$nb9$> 1@inn.qnx.com> …

God have merci, please use BIGGER FONTS…