Index: tapsets.cxx
===================================================================
RCS file: /cvs/systemtap/src/tapsets.cxx,v
retrieving revision 1.174
diff -u -p -r1.174 tapsets.cxx
--- tapsets.cxx	12 Jan 2007 16:33:17 -0000	1.174
+++ tapsets.cxx	25 Jan 2007 22:21:54 -0000
@@ -133,6 +133,7 @@ common_probe_entryfn_prologue (translato
 {
   o->newline() << "struct context* __restrict__ c;";
   o->newline() << "unsigned long flags;";
+  o->newline() << "cycles_t cycles_end, cycles_beg = get_cycles();";
 
   o->newline() << "#ifdef STP_TIMING";
   // NB: we truncate cycles counts to 32 bits.  Perhaps it should be
@@ -220,6 +221,16 @@ common_probe_entryfn_epilogue (translato
   o->newline() << "_stp_exit ();";
   o->newline(-1) << "}";
   o->newline(-1) << "}";
+  o->newline() << "cycles_end = get_cycles();";
+  o->newline() << "c->cycles_sum += cycles_end - cycles_beg;";
+  o->newline() << "if (cycles_end - c->cycles_base > STP_ACCOUNTING_INTERVAL) {";
+  o->newline(1) << "if (c->cycles_sum > STP_ACCOUNTING_THRESHOLD) {";
+  o->newline(1) << "_stp_error (\"probe overhead exceeded threshold\");";
+  o->newline() << "atomic_set (&session_state, STAP_SESSION_ERROR);";
+  o->newline(-1) << "}";
+  o->newline() << "c->cycles_base = cycles_end;";
+  o->newline() << "c->cycles_sum = 0;";
+  o->newline(-1) << "}";
   o->newline() << "atomic_dec (&c->busy);";
 
   o->newline(-1) << "probe_epilogue:"; // context is free
Index: translate.cxx
===================================================================
RCS file: /cvs/systemtap/src/translate.cxx,v
retrieving revision 1.153
diff -u -p -r1.153 translate.cxx
--- translate.cxx	22 Jan 2007 16:56:42 -0000	1.153
+++ translate.cxx	25 Jan 2007 22:21:54 -0000
@@ -793,6 +793,9 @@ c_unparser::emit_common_header ()
   o->newline() << "atomic_t error_count = ATOMIC_INIT (0);";
   o->newline() << "atomic_t skipped_count = ATOMIC_INIT (0);";
   o->newline();
+  o->newline() << "#define STP_ACCOUNTING_INTERVAL 1000000000LL";
+  o->newline() << "#define STP_ACCOUNTING_THRESHOLD 500000000LL";
+  o->newline();
   o->newline() << "struct context {";
   o->newline(1) << "atomic_t busy;";
   o->newline() << "const char *probe_point;";
@@ -810,6 +813,8 @@ c_unparser::emit_common_header ()
   o->newline() << "#ifdef STP_TIMING";
   o->newline() << "Stat *statp;";
   o->newline() << "#endif";
+  o->newline() << "cycles_t cycles_base;";
+  o->newline() << "cycles_t cycles_sum;";
   o->newline() << "union {";
   o->indent(1);