Add node builtin to get NUMA Node ID, as follows:

    $ sudo ./bpftrace -e 'BEGIN{printf("node = %d\n", node);}'
    Attaching 1 probe...
    node = 0

It't useful in multi-node system, like `numactl --hardware`:

    $ numactl --hardware
    [...]
    node   0   1   2   3   4   5   6   7
      0:  10  16  16  16  28  28  22  28
      1:  16  10  16  16  28  28  28  22
      2:  16  16  10  16  22  28  28  28
      3:  16  16  16  10  28  22  28  28
      4:  28  28  22  28  10  16  16  16
      5:  28  28  28  22  16  10  16  16
      6:  22  28  28  28  16  16  10  16
      7:  28  22  28  28  16  16  16  10

docs/reference_guide.md

@@ -1831,6 +1831,7 @@ NetworkManager:1155 /var/lib/sss/mc/passwd (deleted)
 - `gid` - Group ID
 - `nsecs` - Nanosecond timestamp
 - `elapsed` - Nanoseconds since bpftrace initialization
+- `node` - NUMA Node ID
 - `cpu` - Processor ID
 - `comm` - Process name
 - `kstack` - Kernel stack trace

src/ast/irbuilderbpf.cpp

@@ -906,6 +906,19 @@ CallInst *IRBuilderBPF::CreateGetUidGid()
   return createCall(getuidgid_func, {}, "get_uid_gid");
 }
 
+CallInst *IRBuilderBPF::CreateGetNodeId()
+{
+  // u32 bpf_get_numa_node_id(void)
+  // Return: NUMA Node ID
+  FunctionType *getnodeid_func_type = FunctionType::get(getInt64Ty(), false);
+  PointerType *getnodeid_func_ptr_type = PointerType::get(getnodeid_func_type, 0);
+  Constant *getnodeid_func = ConstantExpr::getCast(
+      Instruction::IntToPtr,
+      getInt64(libbpf::BPF_FUNC_get_numa_node_id),
+      getnodeid_func_ptr_type);
+  return createCall(getnodeid_func, {}, "get_node_id");
+}
+
 CallInst *IRBuilderBPF::CreateGetCpuId()
 {
   // u32 bpf_raw_smp_processor_id(void)

src/ast/irbuilderbpf.h

@@ -120,6 +120,7 @@ class IRBuilderBPF : public IRBuilder<>
   CallInst   *CreateGetPidTgid();
   CallInst   *CreateGetCurrentCgroupId();
   CallInst   *CreateGetUidGid();
+  CallInst   *CreateGetNodeId();
   CallInst   *CreateGetCpuId();
   CallInst   *CreateGetCurrentTask();
   CallInst   *CreateGetRandom();

src/ast/passes/codegen_llvm.cpp

@@ -169,6 +169,10 @@ void CodegenLLVM::visit(Builtin &builtin)
       expr_ = b_.CreateLShr(uidgid, 32);
     }
   }
+  else if (builtin.ident == "node")
+  {
+    expr_ = b_.CreateGetNodeId();
+  }
   else if (builtin.ident == "cpu")
   {
     expr_ = b_.CreateGetCpuId();

src/ast/passes/semantic_analyser.cpp

@@ -285,7 +285,7 @@ void SemanticAnalyser::visit(Builtin &builtin)
            builtin.ident == "pid" || builtin.ident == "tid" ||
            builtin.ident == "cgroup" || builtin.ident == "uid" ||
            builtin.ident == "gid" || builtin.ident == "cpu" ||
-           builtin.ident == "rand")
+           builtin.ident == "rand" || builtin.ident == "node")
   {
     builtin.type = CreateUInt64();
     if (builtin.ident == "cgroup" &&

src/lexer.l

@@ -37,7 +37,7 @@ hspace   [ \t]
 vspace   [\n\r]
 space    {hspace}|{vspace}
 path     :(\\.|[_\-\./a-zA-Z0-9#\*])+
-builtin  arg[0-9]|args|cgroup|comm|cpid|cpu|ctx|curtask|elapsed|func|gid|nsecs|pid|probe|rand|retval|sarg[0-9]|tid|uid|username
+builtin  arg[0-9]|args|cgroup|comm|cpid|node|cpu|ctx|curtask|elapsed|func|gid|nsecs|pid|probe|rand|retval|sarg[0-9]|tid|uid|username
 call     avg|buf|cat|cgroupid|clear|count|delete|exit|hist|join|kaddr|kptr|ksym|lhist|macaddr|max|min|ntop|override|print|printf|cgroup_path|reg|signal|sizeof|stats|str|strftime|strncmp|sum|system|time|uaddr|uptr|usym|zero|path|unwatch
 
 /* Don't add to this! Use builtin OR call not both */

tests/codegen/builtin_node.cpp

@@ -0,0 +1,16 @@
+#include "common.h"
+
+namespace bpftrace {
+namespace test {
+namespace codegen {
+
+TEST(codegen, builtin_node)
+{
+  test("kprobe:f { @x = node }",
+
+       NAME);
+}
+
+} // namespace codegen
+} // namespace test
+} // namespace bpftrace

tests/parser.cpp

@@ -53,6 +53,7 @@ TEST(Parser, builtin_variables)
   test("kprobe:f { gid }", "Program\n kprobe:f\n  builtin: gid\n");
   test("kprobe:f { nsecs }", "Program\n kprobe:f\n  builtin: nsecs\n");
   test("kprobe:f { elapsed }", "Program\n kprobe:f\n  builtin: elapsed\n");
+  test("kprobe:f { node }", "Program\n kprobe:f\n  builtin: node\n");
   test("kprobe:f { cpu }", "Program\n kprobe:f\n  builtin: cpu\n");
   test("kprobe:f { curtask }", "Program\n kprobe:f\n  builtin: curtask\n");
   test("kprobe:f { rand }", "Program\n kprobe:f\n  builtin: rand\n");

tests/semantic_analyser.cpp

@@ -146,6 +146,7 @@ TEST(semantic_analyser, builtin_variables)
   test("kprobe:f { gid }", 0);
   test("kprobe:f { nsecs }", 0);
   test("kprobe:f { elapsed }", 0);
+  test("kprobe:f { node }", 0);
   test("kprobe:f { cpu }", 0);
   test("kprobe:f { curtask }", 0);
   test("kprobe:f { rand }", 0);