From f07c3b680a722e27ed55bb5c9719fa5827ebfc75 Mon Sep 17 00:00:00 2001
From: "Frank Ch. Eigler" <fche@elastic.org>
Date: Sat, 13 Jun 2009 18:21:06 -0400
Subject: PR10279: add -DKRETACTIVE=nnnn parameter

* tapsets.cxx (dwarf/kprobe_derived_...::emit_decl/init): Define
  and use KRETPROBE instead of hard-coded max(...) values.  Raise
  the default 50%.
* testsuite/buildok/thirtytwo.stp: New test.
---
 NEWS                            |  5 +++++
 tapsets.cxx                     | 12 ++++++++++--
 testsuite/buildok/thirtytwo.stp | 10 ++++++++++
 3 files changed, 25 insertions(+), 2 deletions(-)
 create mode 100755 testsuite/buildok/thirtytwo.stp

diff --git a/NEWS b/NEWS
index 464b66c1..8fa10401 100644
--- a/NEWS
+++ b/NEWS
@@ -1,3 +1,8 @@
+* What's new
+
+- Systemwide kernel .function.return (kretprobe) maxactive defaults may
+  be overridden with the -DKRETACTIVE=nnn parameter.
+
 * What's new in version 0.9.8
 
 - Miscellaneous new tapset functions:
diff --git a/tapsets.cxx b/tapsets.cxx
index 3ecf2250..0707e052 100644
--- a/tapsets.cxx
+++ b/tapsets.cxx
@@ -2902,6 +2902,10 @@ dwarf_derived_probe_group::emit_module_decls (systemtap_session& s)
   s.op->newline() << "#endif";
   s.op->newline();
 
+  s.op->newline() << "#ifndef KRETACTIVE";
+  s.op->newline() << "#define KRETACTIVE (max(15,6*NR_CPUS))";
+  s.op->newline() << "#endif";
+
   // Forward declare the master entry functions
   s.op->newline() << "static int enter_kprobe_probe (struct kprobe *inst,";
   s.op->line() << " struct pt_regs *regs);";
@@ -3060,7 +3064,7 @@ dwarf_derived_probe_group::emit_module_init (systemtap_session& s)
   s.op->newline() << "if (sdp->maxactive_p) {";
   s.op->newline(1) << "kp->u.krp.maxactive = sdp->maxactive_val;";
   s.op->newline(-1) << "} else {";
-  s.op->newline(1) << "kp->u.krp.maxactive = max(10, 4*NR_CPUS);";
+  s.op->newline(1) << "kp->u.krp.maxactive = KRETACTIVE;";
   s.op->newline(-1) << "}";
   s.op->newline() << "kp->u.krp.handler = &enter_kretprobe_probe;";
   // to ensure safeness of bspcache, always use aggr_kprobe on ia64
@@ -4550,6 +4554,10 @@ kprobe_derived_probe_group::emit_module_decls (systemtap_session& s)
   s.op->newline() << "#endif";
   s.op->newline();
 
+  s.op->newline() << "#ifndef KRETACTIVE";
+  s.op->newline() << "#define KRETACTIVE (max(15,6*NR_CPUS))";
+  s.op->newline() << "#endif";
+
   // Forward declare the master entry functions
   s.op->newline() << "static int enter_kprobe2_probe (struct kprobe *inst,";
   s.op->line() << " struct pt_regs *regs);";
@@ -4695,7 +4703,7 @@ kprobe_derived_probe_group::emit_module_init (systemtap_session& s)
   s.op->newline() << "if (sdp->maxactive_p) {";
   s.op->newline(1) << "kp->u.krp.maxactive = sdp->maxactive_val;";
   s.op->newline(-1) << "} else {";
-  s.op->newline(1) << "kp->u.krp.maxactive = max(10, 4*NR_CPUS);";
+  s.op->newline(1) << "kp->u.krp.maxactive = KRETACTIVE;";
   s.op->newline(-1) << "}";
   s.op->newline() << "kp->u.krp.handler = &enter_kretprobe2_probe;";
   // to ensure safeness of bspcache, always use aggr_kprobe on ia64
diff --git a/testsuite/buildok/thirtytwo.stp b/testsuite/buildok/thirtytwo.stp
new file mode 100755
index 00000000..d97aa50b
--- /dev/null
+++ b/testsuite/buildok/thirtytwo.stp
@@ -0,0 +1,10 @@
+#! /bin/sh
+
+stap -t -p4 -DKRETACTIVE=8888 -e '
+probe kprobe.function("sys_open").return {}
+probe kprobe.function("sys_open").return.maxactive(100) {}
+probe kernel.function("sys_open").return {}
+probe kernel.function("sys_open").return.maxactive(100) {}
+probe syscall.*.return {}
+'
+
-- 
cgit