Re: [Qemu-devel] [PATCH v6 00/20] Refactor trace to allow modular build

["Daniel P. Berrange" <berrange@redhat.com>]

On Wed, Oct 05, 2016 at 04:31:27PM +0100, Stefan Hajnoczi wrote:
> Hmm...the SystemTap simpletrace script does not work anymore for me.  But I've
> tested qemu.git/master and get the same results.
> 
> Did you test it successfully somehow?
> 
> $ cat x86_64-softmmu/qemu-system-x86_64.stp \
>       x86_64-softmmu/qemu-system-x86_64-simpletrace.stp >test.stp
> $ echo 'probe qemu.system.x86_64.simpletrace.* {}' >>test.stp
> 
> $ sudo stap test.stp -c 'x86_64-softmmu/qemu-system-x86_64 -enable-kvm' >/tmp/trace.dat

Do you have pre-existing files for QEMU simpletrace in
/usr/share/systemtap/tapset when you ran this ? If so
this is what is causing you trouble.

Systemtap will match on name, and will thus find multiple
copies of the QME probes - one set in your test.stp and
the other set in /usr/share/systemtap/tapset/qemu-system-x86_64-simpletrace.stp
and activate both of them.

Since my series changed the data format, this will cause problems
as you'll get probes writing new & old formats in the same file

> 
> $ scripts/simpletrace.py trace-events-all /tmp/trace.dat
> Traceback (most recent call last):
>   File "scripts/simpletrace.py", line 217, in <module>
>     run(Formatter())
>   File "scripts/simpletrace.py", line 192, in run
>     process(events, sys.argv[2], analyzer, read_header=read_header)
>   File "scripts/simpletrace.py", line 167, in process
>     for rec in read_trace_records(edict, log):
>   File "scripts/simpletrace.py", line 103, in read_trace_records
>     rec = read_record(edict, idtoname, fobj)
>   File "scripts/simpletrace.py", line 71, in read_record
>     return get_record(edict, idtoname, rechdr, fobj)
>   File "scripts/simpletrace.py", line 43, in get_record
>     name = idtoname[event_id]
> KeyError: 1475680158726993795
> 
> $ scripts/simpletrace.py --no-header trace-events-all /tmp/trace.dat
> Traceback (most recent call last):
>   File "scripts/simpletrace.py", line 217, in <module>
>     run(Formatter())
>   File "scripts/simpletrace.py", line 192, in run
>     process(events, sys.argv[2], analyzer, read_header=read_header)
>   File "scripts/simpletrace.py", line 167, in process
>     for rec in read_trace_records(edict, log):
>   File "scripts/simpletrace.py", line 103, in read_trace_records
>     rec = read_record(edict, idtoname, fobj)
>   File "scripts/simpletrace.py", line 71, in read_record
>     return get_record(edict, idtoname, rechdr, fobj)
>   File "scripts/simpletrace.py", line 43, in get_record
>     name = idtoname[event_id]
> KeyError: 17487890541996943796L



Regards,
Daniel
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