From a38cb7ff39accd9ea600e2409866eb12fb3b8871 Mon Sep 17 00:00:00 2001

From: Stefan Hajnoczi <stefanha@redhat.com>

Date: Tue, 7 Oct 2014 14:06:55 +0200

Subject: [PATCH 37/43] trace: add tracetool simpletrace_stap format

Message-id: <1412690820-31016-7-git-send-email-stefanha@redhat.com>

Patchwork-id: 61611

O-Subject: [RHEL7.1 qemu-kvm PATCH 06/11] trace: add tracetool simpletrace_stap format

Bugzilla: 1088112

RH-Acked-by: Laszlo Ersek <lersek@redhat.com>

RH-Acked-by: Miroslav Rezanina <mrezanin@redhat.com>

RH-Acked-by: Paolo Bonzini <pbonzini@redhat.com>

This new tracetool "format" generates a SystemTap .stp file that outputs

simpletrace binary trace data.

In contrast to simpletrace or ftrace, SystemTap does not define its own

trace format.  All output from SystemTap is generated by .stp files.

This patch lets us generate a .stp file that outputs in the simpletrace

binary format.

This makes it possible to reuse simpletrace.py to analyze traces

recorded using SystemTap.  The simpletrace binary format is especially

useful for long-running traces like flight-recorder mode where string

formatting can be expensive.

Signed-off-by: Stefan Hajnoczi <stefanha@redhat.com>

(cherry picked from commit 3f8b112d6b9ab65e165096582c78154dda1adc69)

Signed-off-by: Stefan Hajnoczi <stefanha@redhat.com>

Downstream tracetool does not have the code reorganization from the

multi-backend tracing changes.  Therefore the stap generation has to

happen in scripts/tracetool/backend/dtrace.py while the

scripts/tracetool/format/simpletrace_stap.py file just emits the file

header.

Remember to import tracetool.backend.simple is_string() in dtrace.py.

Also note that scripts/tracetool/__init__.py filters out disabled events

so we don't need to skip them explicitly.

Signed-off-by: Miroslav Rezanina <mrezanin@redhat.com>

---

 scripts/tracetool/backend/dtrace.py          | 47 ++++++++++++++++++++++++++++

 scripts/tracetool/format/simpletrace_stap.py | 21 +++++++++++++

 2 files changed, 68 insertions(+)

 create mode 100644 scripts/tracetool/format/simpletrace_stap.py

diff --git a/scripts/tracetool/backend/dtrace.py b/scripts/tracetool/backend/dtrace.py

index 614316f..2d8cd2d 100644

--- a/scripts/tracetool/backend/dtrace.py

+++ b/scripts/tracetool/backend/dtrace.py

@@ -14,6 +14,7 @@ __email__      = "stefanha@linux.vnet.ibm.com"

 from tracetool import out

+from tracetool.backend.simple import is_string

 PUBLIC = True

@@ -112,3 +113,49 @@ def stap(events):

         out('}')

     out()

+

+

+def simpletrace_stap(events):

+    for event_id, e in enumerate(events):

+        out('probe %(probeprefix)s.simpletrace.%(name)s = %(probeprefix)s.%(name)s ?',

+            '{',

+            probeprefix=_probeprefix(),

+            name=e.name)

+

+        # Calculate record size

+        sizes = ['24'] # sizeof(TraceRecord)

+        for type_, name in e.args:

+            name = stap_escape(name)

+            if is_string(type_):

+                out('    try {',

+                    '        arg%(name)s_str = %(name)s ? user_string_n(%(name)s, 512) : "<null>"',

+                    '    } catch {}',

+                    '    arg%(name)s_len = strlen(arg%(name)s_str)',

+                    name=name)

+                sizes.append('4 + arg%s_len' % name)

+            else:

+                sizes.append('8')

+        sizestr = ' + '.join(sizes)

+

+        # Generate format string and value pairs for record header and arguments

+        fields = [('8b', str(event_id)),

+                  ('8b', 'gettimeofday_ns()'),

+                  ('4b', sizestr),

+                  ('4b', 'pid()')]

+        for type_, name in e.args:

+            name = stap_escape(name)

+            if is_string(type_):

+                fields.extend([('4b', 'arg%s_len' % name),

+                               ('.*s', 'arg%s_len, arg%s_str' % (name, name))])

+            else:

+                fields.append(('8b', name))

+

+        # Emit the entire record in a single SystemTap printf()

+        fmt_str = '%'.join(fmt for fmt, _ in fields)

+        arg_str = ', '.join(arg for _, arg in fields)

+        out('    printf("%%%(fmt_str)s", %(arg_str)s)',

+            fmt_str=fmt_str, arg_str=arg_str)

+

+        out('}')

+

+    out()

diff --git a/scripts/tracetool/format/simpletrace_stap.py b/scripts/tracetool/format/simpletrace_stap.py

new file mode 100644

index 0000000..b8daa03

--- /dev/null

+++ b/scripts/tracetool/format/simpletrace_stap.py

@@ -0,0 +1,21 @@

+#!/usr/bin/env python

+# -*- coding: utf-8 -*-

+

+"""

+Generate .stp file that outputs simpletrace binary traces (DTrace with SystemTAP only).

+"""

+

+__author__     = "Stefan Hajnoczi <redhat.com>"

+__copyright__  = "Copyright (C) 2014, Red Hat, Inc."

+__license__    = "GPL version 2 or (at your option) any later version"

+

+__maintainer__ = "Stefan Hajnoczi"

+__email__      = "stefanha@redhat.com"

+

+

+from tracetool import out

+

+

+def begin(events):

+    out('/* This file is autogenerated by tracetool, do not edit. */',

+        '')

-- 

1.8.3.1