[libvirt] [PATCH] perf: introduce option --reset

[Nitesh Konkar]

On Mon, Jan 23, 2017 at 7:34 PM, Daniel P. Berrange <berrange at redhat.com>
wrote:

> On Mon, Jan 23, 2017 at 07:26:58PM +0530, Nitesh Konkar wrote:
> > Hi Daniel,
> >
> >
> > On Mon, Jan 23, 2017 at 4:08 PM, Daniel P. Berrange <berrange at redhat.com
> >
> > wrote:
> >
> > > On Mon, Jan 23, 2017 at 04:03:21PM +0530, Nitesh Konkar wrote:
> > >
> > > > @@ -9570,16 +9570,17 @@ qemuDomainSetPerfEvents(virDomainPtr dom,
> > > >      if (def) {
> > > >          for (i = 0; i < nparams; i++) {
> > > >              virTypedParameterPtr param = &params[i];
> > > > -            enabled = param->value.b;
> > > > +            state = param->value.i;
> > >
> > > NACK, this semantic change is not backwards compatible - this will
> break
> > > all applications & language bindings currently using libvirt perf
> events.
> > >
> > > Oh I see . I didn't realize that. Any other API/place you suggest,
> through
> > which
> > we can get this functionality in?
>
> Why not just reset counters to zero when first enabling the perf
> event. If people want to reset them again later, they can just
> disable+enable the event to get the reset
>
I think, if this patch gets in: https://www.redhat.com/
archives/libvir-list/2017-January/msg00956.html
then disable+enable would be equivalent to a reset operation.
As of today, every enable request is creating a new fd, thus leaking the
previous one.

Thanks,
Nitesh

>
> Regards,
> Daniel
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