使用master版本，rdma只能到7GB带宽，attach_ment=512K，无法进一步提高带宽，如何优化

**Describe the bug**

**To Reproduce**

**Expected behavior**

**Versions**
OS:
Compiler:
brpc:
protobuf:

**Additional context/screenshots**

The issue does not identify files, tests, or a reproducible setup. Start by collecting the OS, compiler, brpc, and protobuf versions and documenting the RDMA configuration and workload using master with attach_ment=512K. Done means explaining the 7GB bandwidth limit and documenting a verified optimization or limitation.

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