From: Aliaksei Makarau <aliaksei.makarau@ibm.com>
Date: Tue, 31 Mar 2026 06:40:04 +0000 (+0200)
Subject: This change introduces the shared memory communication (SMC-D) for the cluster network.
X-Git-Url: http://git-server-git.apps.pok.os.sepia.ceph.com/?a=commitdiff_plain;h=e65af75a67b445bf7014842e9d9b3cfbae1e464b;p=ceph.git

This change introduces the shared memory communication (SMC-D) for the cluster network.
SMC-D is faster than ethernet in IBM Z LPARs and/or VMs (zVM or KVM).

Fixes: https://tracker.ceph.com/issues/66702
Signed-off-by: Aliaksei Makarau <aliaksei.makarau@ibm.com>
---

diff --git a/src/common/options/global.yaml.in b/src/common/options/global.yaml.in
index 83c0d869e7a9..9048b094bb5e 100644
--- a/src/common/options/global.yaml.in
+++ b/src/common/options/global.yaml.in
@@ -930,7 +930,7 @@ options:
   level: advanced
   desc: Messenger implementation to use for network communication
   fmt_desc: Transport type used by Async Messenger. Can be ``async+posix``,
-    ``async+dpdk`` or ``async+rdma``. Posix uses standard TCP/IP networking and is
+    ``async+dpdk``, ``async+rdma``, or ``async+smc``. Posix uses standard TCP/IP networking and is
     default. Other transports may be experimental and support may be limited.
   default: async+posix
   flags:
diff --git a/src/msg/async/AsyncMessenger.cc b/src/msg/async/AsyncMessenger.cc
index 04040468d0c8..6451386aa31a 100644
--- a/src/msg/async/AsyncMessenger.cc
+++ b/src/msg/async/AsyncMessenger.cc
@@ -375,6 +375,8 @@ AsyncMessenger::AsyncMessenger(CephContext *cct, entity_name_t name,
     transport_type = "rdma";
   else if (type.find("dpdk") != std::string::npos)
     transport_type = "dpdk";
+  else if (type.find("smc") != std::string::npos)
+    transport_type = "smc";
 
   auto single = &cct->lookup_or_create_singleton_object<StackSingleton>(
     "AsyncMessenger::NetworkStack::" + transport_type, true, cct);
diff --git a/src/msg/async/PosixStack.cc b/src/msg/async/PosixStack.cc
index 5bf088708fc0..58baa7a82f2c 100644
--- a/src/msg/async/PosixStack.cc
+++ b/src/msg/async/PosixStack.cc
@@ -336,7 +336,7 @@ int PosixWorker::connect(const entity_addr_t &addr, const SocketOptions &opts, C
   return 0;
 }
 
-PosixNetworkStack::PosixNetworkStack(CephContext *c)
-    : NetworkStack(c)
+PosixNetworkStack::PosixNetworkStack(CephContext *c, bool try_smc)
+    : NetworkStack(c), try_smc(try_smc)
 {
 }
diff --git a/src/msg/async/PosixStack.h b/src/msg/async/PosixStack.h
index 99d1c340732d..bab3dde34023 100644
--- a/src/msg/async/PosixStack.h
+++ b/src/msg/async/PosixStack.h
@@ -29,8 +29,8 @@ class PosixWorker : public Worker {
   ceph::NetHandler net;
   void initialize() override;
  public:
-  PosixWorker(CephContext *c, unsigned i)
-      : Worker(c, i), net(c) {}
+  PosixWorker(CephContext *c, unsigned i, bool try_smc)
+      : Worker(c, i), net(c, try_smc) {}
   int listen(entity_addr_t &sa,
 	     unsigned addr_slot,
 	     const SocketOptions &opt,
@@ -40,13 +40,14 @@ class PosixWorker : public Worker {
 
 class PosixNetworkStack : public NetworkStack {
   std::vector<std::thread> threads;
+  bool try_smc;
 
   virtual Worker* create_worker(CephContext *c, unsigned worker_id) override {
-    return new PosixWorker(c, worker_id);
+    return new PosixWorker(c, worker_id, try_smc);
   }
 
  public:
-  explicit PosixNetworkStack(CephContext *c);
+  explicit PosixNetworkStack(CephContext *c, bool try_smc);
 
   void spawn_worker(std::function<void ()> &&func) override {
     threads.emplace_back(std::move(func));
diff --git a/src/msg/async/Stack.cc b/src/msg/async/Stack.cc
index d6225b871248..efd290bb4e89 100644
--- a/src/msg/async/Stack.cc
+++ b/src/msg/async/Stack.cc
@@ -66,7 +66,9 @@ std::shared_ptr<NetworkStack> NetworkStack::create(CephContext *c,
   std::shared_ptr<NetworkStack> stack = nullptr;
 
   if (t == "posix")
-    stack.reset(new PosixNetworkStack(c));
+    stack.reset(new PosixNetworkStack(c, false));
+  else if (t == "smc")
+    stack.reset(new PosixNetworkStack(c, true));
 #ifdef HAVE_RDMA
   else if (t == "rdma")
     stack.reset(new RDMAStack(c));
diff --git a/src/msg/async/net_handler.cc b/src/msg/async/net_handler.cc
index f068e2deb724..105259413a32 100644
--- a/src/msg/async/net_handler.cc
+++ b/src/msg/async/net_handler.cc
@@ -32,14 +32,33 @@
 #undef dout_prefix
 #define dout_prefix *_dout << "NetHandler "
 
+#ifndef SMCPROTO_SMC
+  #define SMCPROTO_SMC           0       /* SMC protocol, IPv4 */
+  #define SMCPROTO_SMC6          1       /* SMC protocol, IPv6 */
+#endif
+
 namespace ceph{
 
 int NetHandler::create_socket(int domain, bool reuse_addr)
 {
   int s;
   int r = 0;
+  int protocol = IPPROTO_TCP;
+
+#if defined(AF_SMC)
+  if (this->try_smc) {
+    /* check if socket is eligible for AF_SMC */
+    if (domain == AF_INET || domain == AF_INET6) {
+      if (domain == AF_INET)
+        protocol = SMCPROTO_SMC;
+      else /* AF_INET6 */
+        protocol = SMCPROTO_SMC6;
+      domain = AF_SMC;
+    }
+  }
+#endif
 
-  if ((s = socket_cloexec(domain, SOCK_STREAM, 0)) == -1) {
+  if ((s = socket_cloexec(domain, SOCK_STREAM, protocol)) == -1) {
     r = ceph_sock_errno();
     lderr(cct) << __func__ << " couldn't create socket " << cpp_strerror(r) << dendl;
     return -r;
diff --git a/src/msg/async/net_handler.h b/src/msg/async/net_handler.h
index 755bbf489c56..3cc5debb196b 100644
--- a/src/msg/async/net_handler.h
+++ b/src/msg/async/net_handler.h
@@ -24,9 +24,11 @@ namespace ceph {
     int generic_connect(const entity_addr_t& addr, const entity_addr_t& bind_addr, bool nonblock);
 
     CephContext *cct;
+    bool try_smc;
    public:
     int create_socket(int domain, bool reuse_addr=false);
-    explicit NetHandler(CephContext *c): cct(c) {}
+    explicit NetHandler(CephContext *c, bool try_smc=false): cct(c), try_smc(try_smc) {
+    }
     int set_nonblock(int sd);
     int set_socket_options(int sd, bool nodelay, int size);
     int connect(const entity_addr_t &addr, const entity_addr_t& bind_addr);