[rdma]fix mtu (#957)

Author: qicosmos

include/ylt/coro_io/ibverbs/ib_device.hpp

@@ -109,6 +109,30 @@ struct ib_deleter {
   }
 };
 
+inline std::string mtu_str(ibv_mtu mtu) {
+  std::string str;
+  switch (mtu) {
+    case IBV_MTU_256:
+      str = "IBV_MTU_256";
+      break;
+    case IBV_MTU_512:
+      str = "IBV_MTU_512";
+      break;
+    case IBV_MTU_1024:
+      str = "IBV_MTU_1024";
+      break;
+    case IBV_MTU_2048:
+      str = "IBV_MTU_2048";
+      break;
+    case IBV_MTU_4096:
+      str = "IBV_MTU_4096";
+      break;
+    default:
+      break;
+  }
+  return str;
+}
+
 class ib_device_t {
  public:
   ib_device_t(const ib_config_t& conf) {
@@ -126,6 +150,9 @@ class ib_device_t {
       throw std::system_error(ec);
     }
 
+    ELOG_INFO << "Active MTU: " << mtu_str(attr_.active_mtu) << ", "
+              << "Max MTU: " << mtu_str(attr_.max_mtu);
+
     find_best_gid_index();
 
     ELOG_INFO << "IBDevice " << name_ << ", best gid index " << gid_index_;

include/ylt/coro_io/ibverbs/ib_socket.hpp

@@ -582,7 +582,7 @@ class ib_socket_t {
   void modify_qp_to_rtr(uint32_t remote_qpn, uint16_t dlid, uint8_t* dgid) {
     ibv_qp_attr attr{};
     attr.qp_state = IBV_QPS_RTR;
-    attr.path_mtu = IBV_MTU_4096;
+    attr.path_mtu = state_->device_->attr().active_mtu;
     attr.dest_qp_num = remote_qpn;
     attr.rq_psn = 0;
     attr.max_dest_rd_atomic = 1;

src/coro_io/tests/ibverbs/test_device.cpp

@@ -32,7 +32,7 @@ TEST_CASE("test device") {
   auto pd = dev.pd();
   CHECK(pd);
   CHECK(dev.port() == 1);
-  CHECK(dev.gid_index() == 1);
+  CHECK(dev.gid_index() >= 0);
   auto& attr = dev.attr();
 }