Commit d6b76d68 authored by Stefan Hajnoczi's avatar Stefan Hajnoczi
Browse files

trace: use static event ID mapping in simpletrace.stp 



This is a partial revert of commit
7f1b588f ("trace: emit name <-> ID
mapping in simpletrace header"), which broke the SystemTap flight
recorder because event mapping records may not be present in the ring
buffer when the trace is analyzed.  This means simpletrace.py
--no-header does not know the event ID mapping needed to pretty-print
the trace.

Instead of numbering events dynamically, use a static event ID mapping
as dictated by the event order in the trace-events-all file.

The simpletrace.py script also uses trace-events-all so the next patch
will fix the simpletrace.py --no-header option to take advantage of this
knowledge.

Cc: Daniel P. Berrange <berrange@redhat.com>
Signed-off-by: default avatarStefan Hajnoczi <stefanha@redhat.com>
Reviewed-by: default avatarDaniel P. Berrange <berrange@redhat.com>
Message-id: 20170815084430.7128-2-stefanha@redhat.com
Signed-off-by: default avatarStefan Hajnoczi <stefanha@redhat.com>
parent 5681da29

scripts/tracetool/format/simpletrace_stap.py

+2 −29
Original line number Diff line number Diff line
@@ -22,33 +22,8 @@ def global_var_name(name): 
    return probeprefix().replace(".", "_") + "_" + name



def generate(events, backend, group):

    id_map = global_var_name("event_name_to_id_map")

    next_id = global_var_name("event_next_id")

    map_func = global_var_name("simple_trace_map_event")

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

        '',

        'global %(id_map)s',

        'global %(next_id)s',

        'function %(map_func)s(name)',

        '',

        '{',

        '    if (!([name] in %(id_map)s)) {',

        '        %(id_map)s[name] = %(next_id)s',

        '        name_len = strlen(name)',

        '        printf("%%8b%%8b%%4b%%.*s", 0, ',

        '               %(next_id)s, name_len, name_len, name)',

        '        %(next_id)s = %(next_id)s + 1',

        '    }',

        '    return %(id_map)s[name]',

        '}',

        'probe begin',

        '{',

        '    printf("%%8b%%8b%%8b", 0xffffffffffffffff, 0xf2b177cb0aa429b4, 4)',

        '}',

        '',

        id_map=id_map,

        next_id=next_id,

        map_func=map_func)

        '')



    for event_id, e in enumerate(events):

        if 'disable' in e.properties:
@@ -56,9 +31,7 @@ def generate(events, backend, group): 


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

            '{',

            '    id = %(map_func)s("%(name)s")',

            probeprefix=probeprefix(),

            map_func=map_func,

            name=e.name)



        # Calculate record size
@@ -77,7 +50,7 @@ def generate(events, backend, group): 
        sizestr = ' + '.join(sizes)



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

        fields = [('8b', 'id'),

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

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

                  ('4b', sizestr),

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