| Message ID | 1401194159-30985-3-git-send-email-stefanha@redhat.com |
|---|---|
| State | New |
| Headers | show |
Stefan Hajnoczi writes: > 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> > --- > scripts/tracetool/format/simpletrace_stap.py | 73 ++++++++++++++++++++++++++++ > 1 file changed, 73 insertions(+) > create mode 100644 scripts/tracetool/format/simpletrace_stap.py > diff --git a/scripts/tracetool/format/simpletrace_stap.py b/scripts/tracetool/format/simpletrace_stap.py > new file mode 100644 > index 0000000..4e7f7e7 > --- /dev/null > +++ b/scripts/tracetool/format/simpletrace_stap.py [...] Should the build automatically generate a file using this format? (just for convenience) Also, it might be worth mentioning this file in the "SystemTap" section of "docs/tracing.txt". Thanks, Lluis
On Tue, May 27, 2014 at 03:10:30PM +0200, Lluís Vilanova wrote: > Stefan Hajnoczi writes: > > > 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> > > --- > > scripts/tracetool/format/simpletrace_stap.py | 73 ++++++++++++++++++++++++++++ > > 1 file changed, 73 insertions(+) > > create mode 100644 scripts/tracetool/format/simpletrace_stap.py > > > diff --git a/scripts/tracetool/format/simpletrace_stap.py b/scripts/tracetool/format/simpletrace_stap.py > > new file mode 100644 > > index 0000000..4e7f7e7 > > --- /dev/null > > +++ b/scripts/tracetool/format/simpletrace_stap.py > [...] > > Should the build automatically generate a file using this format? (just for > convenience) > > Also, it might be worth mentioning this file in the "SystemTap" section of > "docs/tracing.txt". I'm still trying to figure out how to best distribute and integrate into make install. Will send a follow-up patch series to hook into the build. I wasn't sure whether to generate the simpletrace-stap file during build or ask the user to customer trace-events to just the events they want to trace. Frank Ch. Eigler of SystemTap fame explained yesterday how to build the simpletrace-stap file once but let the user configure a subset of probes. I think this is the cleanest approach and I am experimenting with that today. Stefan
diff --git a/scripts/tracetool/format/simpletrace_stap.py b/scripts/tracetool/format/simpletrace_stap.py new file mode 100644 index 0000000..4e7f7e7 --- /dev/null +++ b/scripts/tracetool/format/simpletrace_stap.py @@ -0,0 +1,73 @@ +#!/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 +from tracetool.backend.dtrace import binary, probeprefix +from tracetool.backend.simple import is_string +from tracetool.format.stap import stap_escape + + +def generate(events, backend): + out('/* This file is autogenerated by tracetool, do not edit. */', + '') + + for event_id, e in enumerate(events): + if 'disable' in e.properties: + continue + + out('probe %(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) : ""', + ' } catch {', + ' arg%(name)s_str = "<fault>"', + ' }', + ' 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()
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> --- scripts/tracetool/format/simpletrace_stap.py | 73 ++++++++++++++++++++++++++++ 1 file changed, 73 insertions(+) create mode 100644 scripts/tracetool/format/simpletrace_stap.py