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Re: Slow downloads: NSLU2

On Thu, 2007-05-31 at 17:41 +0930, Rod Whitby wrote:
> Bob Cox wrote:
> > In article <1180586594.6055.0.camel@betelgeuse>,
> > David Fokkema <dfokkema@ileos.nl> wrote:
> > 
> >> Well, well, well! On checking, I noticed that my CPU is ~70% idle.
> >> Measuring bandwidth with iperf results in 3.5 Mbit/s. I misread that
> >> last time as 3.5 Mb/s. However, 3.5 Mbit/s should give me only about 450
> >> Kb/s, I certainly get 600 Kb/s over HTTP. My hard disk is running with
> >> Spd=480. That is full speed usb2, right? So, it probably is my network
> >> connection, which is over wifi. I'll try it on cable, some time soon.
> >> Thanks!
> > 
> > Yes - 480 is right; I believe you would see only 12 if it were not USB2.
> 480 is the maximum speed of USB2.  You will not get anywhere near that
> on an NSLU2.
> We don't call it a "slug" for nothing ...

I know. However, it would be nice to get around 30 Mb/s, which is less
than 10% of it. When I 'dd', I get around 7 Mb/s with CPU at ~ 80% which
is almost entirely spent as 'system'. I used:

dd if=/dev/zero of=test.bin bs=1024 count=102400

(I just did the test)

Do you see the same figures? Why is so much time spent as 'system'? I
would've understood if it was 'wait' or something like that... Don't we
have DMA?



> -- Rod

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