Dual PCMCIA Is Very Slow

Jouni Malinen jkmaline at cc.hut.fi
Mon May 26 13:07:45 EDT 2003


On Mon, May 26, 2003 at 12:24:37AM -0500, Michael Shuler wrote:

> I have tried hostap with 1 Zcomax 200mw card on a Soekris and ITX boards and
> am having pretty good success.  Whenever I put a second Zcomax (or any other
> Prism based card) into the Soekris or ITX board, performance goes from
> ~590KB to 100-200KB on one card and under 100KB on the other.

What kind of antenna setup and which channels are you using?

> that needs to be done?  I ultimately want to be able to run 3 Zcomax's off a
> single ITX board (3 120 degree sector panels) but I need it to perform like
> a single card.

When building something like this with Prism2/2.5/3 cards, you should
note that these cards do not support bus mastering/DMA. They will
require host CPU to do I/O with commands that in practice make it busy
wait for the data transfer. Unless you have some special hardware to
resolve this, each Prism2 card will take about 40% of the host CPU when
transmitting data at full rate--no matter how fast the host CPU is.. In
other words, three card setup will most certainly not provide similar
performance as three separate hosts with each using a single card.

-- 
Jouni Malinen                                            PGP id EFC895FA



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