Re: [Qemu-devel] [PATCH v4 6/6] trace: Add QAPI/QMP interfaces to query and control per-vCPU tracing state

[Markus Armbruster]

Lluís Vilanova <address@hidden> writes:

> Markus Armbruster writes:
>
>> Lluís Vilanova <address@hidden> writes:
>>> Signed-off-by: Lluís Vilanova <address@hidden>
>>> Reviewed-by: Stefan Hajnoczi <address@hidden>
>>> ---
>>> monitor.c       |    4 +-
>>> qapi/trace.json |   20 ++++++--
>>> qmp-commands.hx |   17 ++++++-
>>> trace/qmp.c     |  143 
>>> ++++++++++++++++++++++++++++++++++++++++++++-----------
>>> 4 files changed, 147 insertions(+), 37 deletions(-)
>>> 
>>> diff --git a/monitor.c b/monitor.c
>>> index a27e115..bb89877 100644
>>> --- a/monitor.c
>>> +++ b/monitor.c
>>> @@ -910,7 +910,7 @@ static void hmp_trace_event(Monitor *mon, const QDict 
>>> *qdict)
>>> bool new_state = qdict_get_bool(qdict, "option");
>>> Error *local_err = NULL;
>>> 
>>> -    qmp_trace_event_set_state(tp_name, new_state, true, true, &local_err);
>>> +    qmp_trace_event_set_state(tp_name, new_state, true, true, false, 0, 
>>> &local_err);
>>> if (local_err) {
>>> error_report_err(local_err);
>>> }
>>> @@ -1069,7 +1069,7 @@ static void hmp_info_cpustats(Monitor *mon, const 
>>> QDict *qdict)
>>> 
>>> static void hmp_info_trace_events(Monitor *mon, const QDict *qdict)
>>> {
>>> -    TraceEventInfoList *events = qmp_trace_event_get_state("*", NULL);
>>> +    TraceEventInfoList *events = qmp_trace_event_get_state("*", false, 0, 
>>> NULL);
>>> TraceEventInfoList *elem;
>>> 
>>> for (elem = events; elem != NULL; elem = elem->next) {
>
>> The new feature remains inaccessible in HMP.  Any plans to extend HMP?
>> Any reasons not to?
>
> BTW, I was just looking at "info trace-events" and it only shows the state for
> all events (there's no name pattern argument). Is it worth updating HMP 
> knowing
> it should be replaced in favour of the newer QAPI interface?

QMP is not meant as replacement for HMP.  QMP is a stable interface for
machines, HMP is a convenient interface for humans.  New functionality
is usually added to both.  HMP sometimes gets additional convenience
features.  In rare cases, a feature is deemed of no interest to humans,
and left out of HMP.  Is filtering by vCPU such a case?