SV: [ECOS] Gigabit Ethernet throughput on XScale

Lars.I.Nilsson@tietoenator.com Lars.I.Nilsson@tietoenator.com
Tue Jan 13 08:58:00 GMT 2004


The reason I whant to use gigabit Ethernet is that there will be several cameras connected to the same network. With a total bandwith of approximately 200 Mbit. If it was just one camera, 100 Mbit would be sufficient.

If you look at 100 Mbit Ethernet. Is it realistic to have a throughput of 20 Mbit from one camera, on an XScale PXA250 400 MHz. The video encoding is not handled by the Xscale processor, its done in separate hardware.

/Lars

-----Ursprungligt meddelande-----
Från: Andrew Lunn [mailto:andrew@lunn.ch] 
Skickat: den 13 januari 2004 09:29
Till: Nilsson Lars I
Kopia: ecos-discuss@sources.redhat.com; Svensson Jan
Ämne: Re: [ECOS] Gigabit Eternet throughput on XScale

> I have read that, since eCos is a hard real time RTOS, it is not
> suitable for high bandwidth tasks. In that case I guess gigabit Ethernet
> would be overkill on a 400 MHz XScale processor. Is that true?

I would not say "not suitable for high bandwidth". I would say "not
optimized for high bandwidth". eCos puts real time first. Since
networking is none-real time, it comes second. This results in a
little penalty for networking. If you compare eCos with other OS's,
they may give you more network throughput, but at the cost of worse
real time characteristics.

Gigabit ethernet does seem an overkill. Do you even need that amount
of bandwidth. MPEG compression should drop your video down to
something that will go over 100Mbit/s without problem. It will also be
a lot cheaper!

          Andrew

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