Re: [Qemu-devel] [PATCH for-2.8 v1 10/60] trace: remove fixed global event state arrays

[Lluís Vilanova]

Daniel P Berrange writes:

> On Wed, Aug 10, 2016 at 04:00:17PM +0200, Lluís Vilanova wrote:
>> Daniel P Berrange writes:
>> [...]
>> > diff --git a/scripts/tracetool/format/events_c.py 
>> > b/scripts/tracetool/format/events_c.py
>> > index 9203377..bab6404 100644
>> > --- a/scripts/tracetool/format/events_c.py
>> > +++ b/scripts/tracetool/format/events_c.py
>> > @@ -25,7 +25,10 @@ def generate(events, backend):
>> >          '#include "trace/control.h"',
>> >          '')
>> 
>> > -    out('TraceEvent trace_events[TRACE_EVENT_COUNT] = {')
>> > +    out('uint16_t dstate[TRACE_EVENT_COUNT];')
>> > +    out('bool dstate_init[TRACE_EVENT_COUNT];')
>> > +
>> > +    out('static TraceEvent trace_events[TRACE_EVENT_COUNT] = {')
>> 
>> >      for e in events:
>> >          if "vcpu" in e.properties:
>> 
>> I'd rather keep them as 'trace_events_dstate' and 'trace_events_dstate_init' 
>> if
>> most references are auto-generated. Or maybe I just missed something.

> Later patches rename this again, giving it a custom prefix for each
> group

I saw them later, sorry. But I still think these too should be renamed, to make
it clear it's related to tracing.


>> Also, maybe we should just try to get rid of the dstate_init structure. Only
>> vcpu events need late initialization, which could be something like:
>> 
>> trace_events_enabled_count--;
>> dstate[ev->id]--;
>> trace_event_set_state_dynamic(dstate, ev, true);
>> 
>> Non-vcpu events shouldn't need late initialization.

> I'd rather not try to refactor that logic at the same time - it could
> be done as a later patch, or if you want to submit a patch to fix that
> I can rebase on top of it.

I can do that.


>> [...]
>> > diff --git a/stubs/trace-control.c b/stubs/trace-control.c
>> > index fe59836..31566c2 100644
>> > --- a/stubs/trace-control.c
>> > +++ b/stubs/trace-control.c
>> > @@ -11,16 +11,12 @@
>> >  #include "trace/control.h"
>> 
>> 
>> > -void trace_event_set_state_dynamic(TraceEvent *ev, bool state)
>> > +void trace_event_set_state_dynamic(uint16_t *dstate, TraceEvent *ev, bool 
>> > state)
>> >  {
>> > -    TraceEventID id;
>> >      assert(trace_event_get_state_static(ev));
>> > -    id = trace_event_get_id(ev);
>> > -    trace_events_enabled_count += state - trace_events_dstate[id];
>> > -    trace_events_dstate[id] = state;
>> >  }
>> 
>> Should not be empty (here, stub means it's not target code).

> Oh hmm, for qemu-img & friends, i geuss

Exactly.


Cheers,
  Lluis