[Qemu-devel] Re: [RFC][PATCH 0/6] trace-state: make the behaviour of "disable" consistent across all backends

[Stefan Hajnoczi <stefanha@gmail.com>]

On Tue, Apr 5, 2011 at 2:30 PM, Stefan Hajnoczi <stefanha@gmail.com> wrote:
> On Mon, Apr 4, 2011 at 10:49 PM, Lluís <xscript@gmx.net> wrote:
>> This patch defines the "disable" trace event state to always use the "nop"
>> backend.
>>
>> As a side-effect, all events are now enabled (without "disable") by default, as
>> all backends (except "stderr") have programmatic support for dynamically
>> (de)activating each trace event.
>>
>> In order to make this true, the "simple" backend now has a "-trace
>> events=<file>" argument to let the user select which events must be enabled from
>> the very beginning.
>>
>> Signed-off-by: Lluís Vilanova <vilanova@ac.upc.edu>
>> ---
>>
>> Lluís Vilanova (6):
>>      trace: [ust] fix generation of 'trace.c' on events without args
>>      trace: generalize the "property" concept in the trace-events file
>>      trace-state: always use the "nop" backend on events with the "disable" keyword
>>      trace-state: [simple] disable all trace points by default
>>      trace-state: [simple] add "-trace events" argument to control initial state
>>      trace: enable all events
>>
>>
>>  docs/tracing.txt  |   12 +-
>>  qemu-config.c     |    5 +
>>  qemu-options.hx   |   18 ++
>>  scripts/tracetool |   88 +++++-------
>>  trace-events      |  385 ++++++++++++++++++++++++++---------------------------
>>  vl.c              |   94 ++++++++-----
>>  6 files changed, 313 insertions(+), 289 deletions(-)
>
> Excellent, thanks for implementing this.  I'll review the patches in
> detail shortly.

I've left feedback on the individual patches.  This is a nice cleanup,
thanks for doing this work!

The stderr backend is impacted - but not severely.  You now need to
disable all trace events that should not generate output.  Previously
it was the opposite; you needed to enable all trace events that should
generate output.

Adding Prerna (simpletrace) and Fabien (stderr) on CC so they can take a look.

I'd like to merge v2 into my tracing tree and send the qemu.git
maintainer a pull request soon.

Stefan