From 7ad9d4f58308c4d8f35f2212ce82212301dfeeff Mon Sep 17 00:00:00 2001
From: fche <fche>
Date: Tue, 2 Jan 2007 04:33:41 +0000
Subject: 2007-01-01  Frank Ch. Eigler  <fche@redhat.com>

	* configure.ac: Bump version to 0.5.12 for release.
	* configure: Regenerated.
	* NEWS, AUTHORS: Populate & repopulate.
	* examples/*: Added several .stp/.txt files from the wiki.
---
 examples/futexes.stp | 36 ++++++++++++++++++++++++++++++++++++
 1 file changed, 36 insertions(+)
 create mode 100644 examples/futexes.stp

(limited to 'examples/futexes.stp')

diff --git a/examples/futexes.stp b/examples/futexes.stp
new file mode 100644
index 00000000..608ce0de
--- /dev/null
+++ b/examples/futexes.stp
@@ -0,0 +1,36 @@
+#! stap
+
+# This script tries to identify contended user-space locks by hooking
+# into the futex system call.
+
+global thread_thislock # short
+global thread_blocktime # 
+global FUTEX_WAIT = 0, FUTEX_WAKE = 1
+
+global lock_waits # long-lived stats on (tid,lock) blockage elapsed time
+global process_names # long-lived pid-to-execname mapping
+
+probe syscall.futex {  
+   if (op != FUTEX_WAIT) next  # we don't care about originators of WAKE events
+   t = tid ()
+   process_names[pid()] = execname()
+   thread_thislock[t] = $uaddr
+   thread_blocktime[t] = gettimeofday_us()
+}
+
+probe syscall.futex.return {  
+   t = tid()
+   ts = thread_blocktime[t]
+   if (ts) {
+     elapsed = gettimeofday_us() - ts
+     lock_waits[pid(), thread_thislock[t]] <<< elapsed
+     delete thread_blocktime[t]
+     delete thread_thislock[t]
+   }
+}
+
+probe end {
+   foreach ([pid+, lock] in lock_waits) 
+     printf ("%s[%d] lock %p contended %d times, %d avg us\n",
+       process_names[pid], pid, lock, @count(lock_waits[pid,lock]), @avg(lock_waits[pid,lock]))
+}
-- 
cgit