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Altera_Forum's avatar
Altera_Forum
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19 years ago

Speed using PCI Target Mode

hello, girls and guys, has someone used the Altera PCI Developpment board?

or does anyone has some experience about the PCI Target Mode?

now i am busying with some designs which contains the PCI to transfer data from the user board to the PC host. First step, i use the Altera PCI Board to do a simple test, and the design file is the Altera example, while detailed information can be found with the an390.pdf.

through the testing, i have an amazing result:

1. the speed for target write is just 10MB/s

2. the speed for target read is even slower, only 3.5 MB/s;

but

3. the speed for master write is about 110MB/s,

4. the speed for master read is about 90MB/s.

in fact, for master mode, we can adjust the Latency Timer in configuration register,

it's really workable, we can change the speed dramaticaly;while for the target mode, i can not find the speed adjusting information.

so the question is:

why the target read/write is so slow? is there any limitation with the altear PCI IP?

and by the way, is there any limitation with the PCI IP in SOPC? or the PCI IP in MegaCore Walkthrough is the same with the corresponding guy in SOPC?

really expecting your help!

any ideas and suggestions are welcome.

thanks in advance!

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1 Reply

  • Altera_Forum's avatar
    Altera_Forum
    Icon for Honored Contributor rankHonored Contributor
    19 years ago

    Latency Timer configuration register is intended only for master mode. To receive the guaranteed high speed in target mode difficultly. Speed most likely does not depend from altera PCI IP. It is very strongly depends on many factors. First from a chipset of your motherboard. Secondly how you write or read data from the controller. Try to use mmx, sse, sse2 mov commands instead IA32 mov and burst reading or writing.