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| author | Dave Brolley <brolley@redhat.com> | 2008-08-08 15:15:19 -0400 |
|---|---|---|
| committer | Dave Brolley <brolley@redhat.com> | 2008-08-08 15:15:19 -0400 |
| commit | 71906647386a9684086b0542318b536d95ae089c (patch) | |
| tree | fb0348d7bb34095e95ad830da8e832bad9187a55 /testsuite/systemtap.examples/io/io_submit.stp | |
| parent | d5658775da9fa0ac792eb3f874df9f7c4d60de7e (diff) | |
| parent | f1118e1032612170cae8cd979cd529722ad95fdb (diff) | |
| download | systemtap-steved-71906647386a9684086b0542318b536d95ae089c.tar.gz systemtap-steved-71906647386a9684086b0542318b536d95ae089c.tar.xz systemtap-steved-71906647386a9684086b0542318b536d95ae089c.zip | |
Merge branch 'master' of ssh://sources.redhat.com/git/systemtap
Conflicts:
ChangeLog
testsuite/ChangeLog
Diffstat (limited to 'testsuite/systemtap.examples/io/io_submit.stp')
| -rw-r--r-- | testsuite/systemtap.examples/io/io_submit.stp | 71 |
1 files changed, 71 insertions, 0 deletions
diff --git a/testsuite/systemtap.examples/io/io_submit.stp b/testsuite/systemtap.examples/io/io_submit.stp new file mode 100644 index 00000000..735dd6f9 --- /dev/null +++ b/testsuite/systemtap.examples/io/io_submit.stp @@ -0,0 +1,71 @@ +#!/bin/env stap
+#
+# Copyright (C) 2007 Oracle Corp. Chris Mason <chris.mason@oracle.com>
+#
+# This was implemented to find the most common causes of schedule during
+# the AIO io_submit call. It does this by recording which pids are inside
+# AIO, and recording the current stack trace if one of those pids is
+# inside schedule.
+# When the probe exits, it prints out the 30 most common call stacks for
+# schedule().
+#
+# This file is free software. You can redistribute it and/or modify it under
+# the terms of the GNU General Public License (GPL); either version 2, or (at
+# your option) any later version.
+
+global in_iosubmit
+global traces
+
+/*
+ * add a probe to sys_io_submit, on entry, record in the in_iosubmit
+ * hash table that this proc is in io_submit
+ */
+probe syscall.io_submit {
+ in_iosubmit[tid()] = 1
+}
+
+/*
+ * when we return from sys_io_submit, record that we're no longer there
+ */
+probe syscall.io_submit.return {
+ /* this assumes a given proc will do lots of io_submit calls, and
+ * so doesn't do the more expensive "delete in_iosubmit[p]". If
+ * there are lots of procs doing small number of io_submit calls,
+ * the hash may grow pretty big, so using delete may be better
+ */
+ in_iosubmit[tid()] = 0
+}
+
+/*
+ * every time we call schedule, check to see if we started off in
+ * io_submit. If so, record our backtrace into the traces histogram
+ */
+probe kernel.function("schedule") {
+ if (tid() in in_iosubmit) {
+ traces[backtrace()]++
+
+ /*
+ * change this to if (1) if you want a backtrace every time
+ * you go into schedule from io_submit. Unfortunately, the traces
+ * saved into the traces histogram above are truncated to just a
+ * few lines. so the only way to see the full trace is via the
+ * more verbose print_backtrace() right here.
+ */
+ if (0) {
+ printf("schedule in io_submit!\n")
+ print_backtrace()
+ }
+ }
+}
+
+/*
+ * when stap is done (via ctrl-c) go through the record of all the
+ * trace paths and print the 30 most common.
+ */
+probe end {
+ foreach (stack in traces- limit 30) {
+ printf("%d:", traces[stack])
+ print_stack(stack);
+ }
+}
+
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