Sending rate decrease in TCP bidirectional test

[Varun Sharma]

Hi,

I am using iperf v 2.0.5 for testing 10G card. Its a dual port card. Two 16
core machines with 64GB RAM are connected back to back.

In *TCP Bidirectional test* case sending throughput decrease as compare to *TCP
Unidirectional test* case sending .

All cases use default setting . No extra parameter is set.


In case of 4 Client threads Output comes :--

Unidirectional Send Process --- *9.6* Gbps

Bidirectional Send Process ----  *4.9*  Gbps


In case of 8 Client threads Output comes :--

Unidirectional Send Process --- *9.7* Gbps

Bidirectional Send Process -- *6.4* Gbps


In case of 16 Client threads Output comes :--

 Unidirectional Send Process ---* 9.7* Gbps

 Bidirectional Send Process --    *8* Gbps


 Is this problem regarding TCP/IP stack or nic card ?

Regards

varun
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