Questions about some member variables of the BroadcomNode class

[YuTao-Zhangyy]

Greetings to the esteemed author:

Recently I've been carefully analyzing your project ns3-rdma-master code, and I found some member variables in BroadcomNode hard to understand. In order to better sort out the key steps of the DCQCN protocol, could you please help me explain the meaning of the following variables?

for example，m_usedIngressPGBytes[pCnt][qCnt]、m_usedIngressPortBytes[pCnt]、m_usedIngressSPBytes[4]、m_usedIngressPGHeadroomBytes[pCnt][qCnt]、m_usedEgressQMinBytes[pCnt][qCnt]、m_usedEgressQSharedBytes[pCnt][qCnt]、m_usedEgressPortBytes[pCnt]、m_usedEgressSPBytes[4].

In fact, I don't understand the meaning of the fields PGBytes, SPBytes, PGHeadroomBytes, QMinBytes, QSharedBytes. If you can help me with these queries, perhaps I can deduce the meaning of the other variables on my own.

I wish you all the best.

[bobzhuyb]

These are related to Broadcom switches' internal buffer management. PG stands for priority group (I think), SP means service pool, Q is short for queue. You have to understand the Broadcom buffer management first to really understand what they mean. I cannot share those Broadcom documents... If you have some kind of support from Broadcom, you can ask them for Trident or Tomahawk's buffer management documents.

[YuTao-Zhangyy]

Thank you very much for your prompt reply, I will try to search for some materials to help with learning. Thank you again.