Virtual Channel Concept

Comments and questions to the author of the "Down to the TLP" posts (Eli Billauer)

Virtual Channel Concept

Postby Guest » Mon Oct 19, 2015 6:51 am

Hi,
Can you elaborate little more about virtual channels ?
Guest
 

Re: Virtual Channel Concept

Postby support » Mon Oct 19, 2015 6:48 pm

Hello,

Frankly speaking, I don't find the issue of virtual channels interesting, so I know little about this topic. I can't think about a single real-life case in which virtual channels would be the sensible solution.

So unfortunately, I can't say much more than that I think it was a mistake to have this thing in the PCIe standard to begin with. Just made switches much more complicated. :mrgreen:

Regards,
Eli
support
 
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Re: Virtual Channel Concept

Postby moopau » Tue Nov 21, 2017 11:05 am

TLP and virtual channels.

when you look to whatever OS(windows, linux, qnx....) all they use one virtual channel = 0, so all communication to/from each pcie device/bridge/switch goes through one channel

if you have a real-time application with for example a profinet interface then it can have impact on the real-time aspect.

but by select specially for the profinet-interface VC1( it a higher priority ) the profinet interface/driver get a highest priority

in the header field of a TLP-packet you find TC-field,(traffic class) when it is equal to 1 and VC1 is init with TC1 then this TLP-packet use VC1 instead of VC0 which is used default by all other pcie-devices

Paul
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