Re: [PATCHv2] trace-cmd: add kvm_mmu_prepare_zap_page even and fix kvm_mmu_get_page event output in kvm plugin

[Steven Rostedt <srostedt@redhat.com>]

On Mon, 2013-01-28 at 13:12 +0200, Gleb Natapov wrote:
> Ping.
> 
> On Thu, Dec 27, 2012 at 01:34:15PM +0200, Gleb Natapov wrote:
> > kvm_mmu_zap_page event was renamed to kvm_mmu_prepare_zap_page. Add new
> > even, but leave the old one to parse older traces.  Print out "created"
> > field for kvm_mmu_get_page event.
> > 
> > Signed-off-by: Gleb Natapov <gleb@redhat.com>
> > diff --git a/plugin_kvm.c b/plugin_kvm.c
> > index 55812ef..9b376d8 100644
> > --- a/plugin_kvm.c
> > +++ b/plugin_kvm.c
> > @@ -382,7 +382,7 @@ static int kvm_mmu_print_role(struct trace_seq *s, struct pevent_record *record,
> >  	} else
> >  		trace_seq_printf(s, "WORD: %08x", role.word);
> >  
> > -	pevent_print_num_field(s, " root %u",  event,
> > +	pevent_print_num_field(s, " root %u ",  event,
> >  			       "root_count", record, 1);
> >  
> >  	if (pevent_get_field_val(s, event, "unsync", record, &val, 1) < 0)
> > @@ -397,6 +397,11 @@ static int kvm_mmu_get_page_handler(struct trace_seq *s, struct pevent_record *r
> >  {
> >  	unsigned long long val;
> >  
> > +	if (pevent_get_field_val(s, event, "created", record, &val, 1) < 0)

Is "created" a new field? Or is it something that has always been there
but never displayed?

If it is new, then instead of returning '-1' if it's not found, could
you just ignore it. I don't want old kernels to start breaking on new
trace-cmd plugins.

Thanks,

-- Steve

> > +		return -1;
> > +
> > +	trace_seq_printf(s, "%s ", val ? "new" : "existing");
> > +
> >  	if (pevent_get_field_val(s, event, "gfn", record, &val, 1) < 0)
> >  		return -1;
> >  
> > @@ -433,5 +438,9 @@ int PEVENT_PLUGIN_LOADER(struct pevent *pevent)
> >  	pevent_register_event_handler(pevent, -1, "kvmmmu", "kvm_mmu_zap_page",
> >  				      kvm_mmu_print_role, NULL);
> >  
> > +	pevent_register_event_handler(pevent, -1, "kvmmmu",
> > +			"kvm_mmu_prepare_zap_page", kvm_mmu_print_role,
> > +			NULL);
> > +
> >  	return 0;
> >  }
> > --
> > 			Gleb.
> > --
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> 
> --
> 			Gleb.