performance about disni HOT 5 OPEN

You should expect latency slightly higher than native maybe around 5-10us overhead max.
The code snippet you posted is problematic as you should post the receive request before the send is issued. Worst case the send from the other side is issued before the receive is posted and you will run into retries or on some transports your connections will be aborted.
I recommend running the benchmarks provided here: https://github.com/zrlio/disni/tree/master/src/test/java/com/ibm/disni/benchmarks

from disni.

I refactored the original benchmark code you reference into separate

1. init and connect
2. send msg to server and recv response from server

but I still use the CustomClientEndpoint. The CustomClientEndpoint::init() does a pre post recv request as the last line:
System.out.println("SimpleClient::initiated recv");
this.postRecv(wrList_recv).execute().free();
But as you mentioned, if I run the benchmark code directly using the default 1000 loops I do see about 40us average which is not bad.
java com.ibm.disni.benchmarks.RDMAvsTcpBenchmarkClient -a 192.168.0.37 -p 20886 -s 1024

SimpleClient::initiated recv
RDMAvsTcpBenchmarkClient::client channel set up
RDMA result:
Total time: 38.721645 ms
Bidirectional bandwidth: 0.04925794430511669 Gbytes/s
Bidirectional bandwidth: 0.3940635544409335 Gbits/s
Bidirectional average latency: 0.038721645 ms

from disni.

I recommend running more than just 1000 loops. 38ms total runtime is probably not enough to get stable/good performance. You have to keep in mind that in Java it takes a while until all code path are JIT compiled so initially there is a lot more overhead.

from disni.