Re: [Qemu-devel] [PATCH 1/2 v16] fsdev: add IO throttle support to fsdev devices

[Greg Kurz]

On Tue, 7 Feb 2017 00:15:33 +0100
Greg Kurz <address@hidden> wrote:

> On Mon, 6 Feb 2017 13:36:43 -0600
> Eric Blake <address@hidden> wrote:
> 
> > On 02/03/2017 05:57 AM, Pradeep Jagadeesh wrote:  
> > > This patchset adds the throttle support for the 9p-local driver.
> > > For now this functionality can be enabled only through qemu cli options.
> > > QMP interface and support to other drivers need further extensions.    
> > 
> > This part is a bit scary - if 2.9 is released with just the cli option
> > and not the QMP interface, then how does someone like libvirt introspect
> > whether the feature is available for use?
> >   
> 
> I'm not aware of anything related to fsdev in QMP... and libvirt seems to
> only parse the output of -help to guess fsdev capabilities.

Oops, reading some more libvirt code I now see that libvirt doesn't parse
-help anymore with QEMU >= 1.2.0... sorry for the noise :)

> And indeed,
> qemu-options.hx doesn't expose this new feature.
> 
> > Please make sure we don't reach 2.9 with only a half-baked feature;
> > whether that means finishing the QMP work or temporarily disabling the
> > cli additions until a later release can finish the work.
> >   
> 
> Would this be ok to add the missing bits in qemu-options.hx or do you
> expect more ?
> 
> Cheers.
> 
> --
> Greg

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