Re: Compact flash speed

["Christer O. Andersson" <christer%a-son.net@localhost>]

On Tue, Mar 21, 2006 at 09:18:32PM -0500, Michael Wileman wrote:
> On Tue, 21 Mar 2006, Christer O. Andersson wrote:
> 
> >On Tue, Mar 21, 2006 at 12:02:50PM -0500, Michael Wileman wrote:
> >>Has anyone compared these two types to see if there is a speed
> >>difference when used in the Jornada CF slot? What's the maximum
> >>speed the Jornada will read and write? Also, is the whole Ultra II
> >>brand just marketing, or is there a real difference in the hardware?
> >
> >I have a 1 GB Extreme III and a 256 MB standard, maybe I could test
> >those?
> >
> >What would be a good test, something like
> >time dd if=/dev/zero of=file.txt
> >and
> >time dd if=file.txt of=/dev/null perhaps?
> 
> That looks good to me.
> 
> Mike
> 

With a 1GB Etreme III my 680 gives me:
$ time dd if=/dev/zero of=tst.file bs=65536 count=512
512+0 records in
512+0 records out
33554432 bytes transferred in 10.531 secs (3186253 bytes/sec)
   10.65s real     1.95s user     0.04s system
$ time dd if=tst.file of=/dev/null bs=65536
512+0 records in
512+0 records out
33554432 bytes transferred in 6.811 secs (4926505 bytes/sec)
    6.92s real     3.45s user     0.09s system
$ 

Using a standard 256 MB CF I get:
$ time dd if=/dev/zero of=tst.file bs=65536 count=512  
512+0 records in
512+0 records out
33554432 bytes transferred in 10.335 secs (3246679 bytes/sec)
   10.45s real     3.10s user     0.03s system
$ time dd if=tst.file of=/dev/null bs=65536           
512+0 records in
512+0 records out
33554432 bytes transferred in 6.983 secs (4805159 bytes/sec)
    7.09s real     3.87s user     0.09s system


On my i386 laptop I get this with my 1GB Extreme III and a CF/PCMCIA
adapter:
# time dd if=/dev/zero of=tst.file bs=65536 count=512
512+0 records in
512+0 records out
33554432 bytes transferred in 18.365 secs (1827085 bytes/sec)
   18.63s real     0.00s user     0.07s system
# time dd if=tst.file of=/dev/null bs=65536
512+0 records in
512+0 records out
33554432 bytes transferred in 0.043 secs (780335627 bytes/sec)
    0.04s real     0.00s user     0.04s system

I don't know how the CF/PCMCIA adapter affects data speeds but the
read from flash looks really strange! This test probably has no
value at all.

Judging from the measurements on the 680, if they are accurate,
there is little need in buying anything but standard CF, at least
if it won't see any use elsewhere than in the 680. The Extreme III
is supposed to do 20MB/s read and write, so should be even faster
than the Ultra II. It seems to be the 680 that limits the transfer
rate. By the way, the Ultra II is supposed to do 10MB/s read and
9MB/s write, which is faster than a standard CF, but I forget how
much.


-- 
Christer O. Andersson
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