Add SO_INCOMING_CPU support to net.sock_option_flag_in

doc/admin-guide/files/records.yaml.en.rst

@@ -5055,9 +5055,11 @@ Sockets
         PACKET_MARK (16)
         PACKET_TOS (32)
         TCP_NOTSENT_LOWAT (64)
+        INCOMING_CPU (128)
 
    Note: If MPTCP is enabled, TCP_NODELAY is only supported on Linux kernels 5.17+. TCP_FASTOPEN
    and TCP_NOTSENT_LOWAT socket options are currently not supported.
+
 .. note::
 
    This is a bitmask and you need to decide what bits to set.  Therefore,
@@ -5069,6 +5071,20 @@ Sockets
    To allow TCP Fast Open for client sockets on Linux, bit 2 of
    the ``net.ipv4.tcp_fastopen`` sysctl must be set.
 
+.. note::
+
+   As for SO_INCOMING_CPU, using it with SO_REUSEPORT and exec_thread affinity 4 is recommended.
+
+   .. code-block:: yaml
+
+      ts:
+        accept_threads: 0
+        exec_thread:
+          listen: 1
+          affinity: 4
+        net:
+         sock_option_flag_in: 0x80
+
 .. ts:cv:: CONFIG proxy.config.net.sock_send_buffer_size_out INT 0
    :overridable:
 

include/iocore/eventsystem/EThread.h

@@ -34,6 +34,11 @@
 #include "iocore/eventsystem/ProtectedQueue.h"
 #include "tsutil/Histogram.h"
 
+#if TS_USE_HWLOC
+struct hwloc_obj;
+using hwloc_obj_t = hwloc_obj *;
+#endif
+
 // TODO: This would be much nicer to have "run-time" configurable (or something)
 #define PER_THREAD_DATA (1024 * 1024)
 
@@ -333,9 +338,15 @@ class EThread : public Thread
 
   static constexpr int NO_ETHREAD_ID = -1;
   int                  id            = NO_ETHREAD_ID;
-  unsigned int         event_types   = 0;
-  bool                 is_event_type(EventType et);
-  void                 set_event_type(EventType et);
+
+#if TS_USE_HWLOC
+  hwloc_obj_t hwloc_obj = nullptr;
+#endif
+
+  unsigned int event_types = 0;
+
+  bool is_event_type(EventType et);
+  void set_event_type(EventType et);
 
   // Private Interface
 

include/iocore/net/NetVCOptions.h

@@ -145,6 +145,8 @@ struct NetVCOptions {
   static uint32_t const SOCK_OPT_PACKET_TOS = 32;
   /// Value for TCP_NOTSENT_LOWAT @c sockopt_flags
   static uint32_t const SOCK_OPT_TCP_NOTSENT_LOWAT = 64;
+  /// Value for SO_INCOMING_CPU @c sockopt_flags
+  static uint32_t const SOCK_OPT_INCOMING_CPU = 128;
 
   uint32_t packet_mark;
   uint32_t packet_tos;

src/iocore/eventsystem/UnixEventProcessor.cc

@@ -266,6 +266,8 @@ ThreadAffinityInitializer::set_affinity(int, Event *)
   if (obj_count > 0) {
     // Get our `obj` instance with index based on the thread number we are on.
     hwloc_obj_t obj = hwloc_get_obj_by_type(ink_get_topology(), obj_type, t->id % obj_count);
+    t->hwloc_obj    = obj;
+
 #if HWLOC_API_VERSION >= 0x00010100
     int   cpu_mask_len = hwloc_bitmap_snprintf(nullptr, 0, obj->cpuset) + 1;
     char *cpu_mask     = static_cast<char *>(alloca(cpu_mask_len));

src/iocore/net/Connection.cc

@@ -27,11 +27,17 @@
   Commonality across all platforms -- move out as required.
 
 **************************************************************************/
-#include "tscore/ink_platform.h"
-#include "tscore/ink_defs.h"
 
 #include "P_Net.h"
 
+#include "tscore/ink_defs.h"
+#include "tscore/ink_platform.h"
+#include "tscore/ink_sock.h"
+
+#if TS_USE_HWLOC
+#include <hwloc.h>
+#endif
+
 #ifdef SO_ACCEPTFILTER
 #include <sys/param.h>
 #include <sys/linker.h>
@@ -49,6 +55,7 @@ DbgCtl dbg_ctl_http_tproxy{"http_tproxy"};
 DbgCtl dbg_ctl_proxyprotocol{"proxyprotocol"};
 DbgCtl dbg_ctl_iocore_net_server{"iocore_net_server"};
 DbgCtl dbg_ctl_connection{"connection"};
+DbgCtl dbg_ctl_iocore_thread{"iocore_thread"};
 
 } // end anonymous namespace
 
@@ -238,6 +245,23 @@ Server::setup_fd_for_listen(bool non_blocking, const NetProcessor::AcceptOptions
 #endif
   }
 
+#ifdef SO_INCOMING_CPU
+  if (opt.sockopt_flags & NetVCOptions::SOCK_OPT_INCOMING_CPU) {
+    int      cpu     = 0;
+    EThread *ethread = this_ethread();
+
+#ifdef TS_USE_HWLOC
+    cpu = ethread->hwloc_obj->os_index;
+#else
+    cpu = ethread->id;
+#endif
+    if (safe_setsockopt(fd, SOL_SOCKET, SO_INCOMING_CPU, &cpu, sizeof(cpu)) < 0) {
+      goto Lerror;
+    }
+    Dbg(dbg_ctl_iocore_thread, "SO_INCOMING_CPU - fd=%d cpu=%d", fd, cpu);
+  }
+#endif
+
   if ((opt.sockopt_flags & NetVCOptions::SOCK_OPT_NO_DELAY) && setsockopt_on(fd, IPPROTO_TCP, TCP_NODELAY) < 0) {
     goto Lerror;
   }