[linux-dvb] Re: More than 4 DVB cards - again

["Irek Defee" <irek.defee@ondems.com>]

-----Original Message-----
From: linux-dvb-bounce@linuxtv.org [mailto:linux-dvb-bounce@linuxtv.org]
On Behalf Of Peter Maersk-Moller
Sent: 24. kesäkuuta 2004 16:01
To: Irek Defee
Cc: linux-dvb@linuxtv.org
Subject: [linux-dvb] Re: More than 4 DVB cards - again

>You mean in practice you can expect to transmit a maximum of 2x400Mbps
>over the PCI bus ? it will of course depends on the way the PCI bus
>is used. There are many modes of transfer over the bus.

I mean you can send from a device to the network 400 Mb/s. I am not
based on speculation here. We were doing in the past experiments in
transferring data form disk arrays and RAMdisk to Gigabit Ethernet
network. This number was obtained for 32bit/33MHz PCI bus, different
transfer modes were not significant factor.

>One other thing, the PCI bus is no longer the only mean of transfer
>data externally. I'm using HS USB2.0 ports to off-load data onto
>encoder machines. On some motherboards the on-board usb chip
>shares the bandwidth limitation of the PCI-bus, on some they
>DON'T. Furthermore, there are motherboards with network adapters
>and other adapters included in the North-bridge with direct access
>to RAM instead of connected through the south-bridge. There
>are also motherboards with more than one PCI-bus.
 
This is true, there are more advanced architectures which could 
provide more output. Even going to faster PCI buses: 66 MHz doubles 
the throughput and 64-bit doubles it again.  

>I have one here with 5 slots, but I have a problem getting more than
>4 receivers as mentioned in the beginning of the thread.

It is strange that this issue has been downgraded comparing to kernel
2.4. For me it’s a huge factor not to upgrade to 2.6:). 

But I would suggest to developers to  take this into account and provide
direct plug-and-play support for more than 4 cards. 6 PCI slots is the
maximum amount in PC motherboards which also have on-board network
adapter. Thus, it is natural to think that high-end installations
may include 6 cards. Then, there are also more exotic server boards
with several PCI buses and they could take more than 6 cards which
could also be considered.