[PATCH 14/16] conf: Expose QEMU's main loop object

[Daniel P. Berrangé]

On Thu, Jun 02, 2022 at 01:54:39PM +0200, Peter Krempa wrote:
> On Thu, Jun 02, 2022 at 09:18:04 +0200, Michal Privoznik wrote:
> > As of v7.0.0-877-g70ac26b9e5 QEMU exposes its main event loop as
> > an QMP object. In the very next commit (v7.0.0-878-g71ad4713cc)
> > it was extended for thread-pool-min and thread-pool-max
> > attributes. Expose them under new <mainloop/> element.
> > 
> > Signed-off-by: Michal Privoznik <mprivozn at redhat.com>
> > ---
> >  docs/formatdomain.rst                         |  5 ++
> >  src/conf/domain_conf.c                        | 57 +++++++++++++++++++
> >  src/conf/domain_conf.h                        |  8 +++
> >  src/conf/schemas/domaincommon.rng             | 15 +++++
> >  src/conf/virconftypes.h                       |  2 +
> >  .../iothreads-ids-pool-sizes.xml              |  1 +
> >  6 files changed, 88 insertions(+)
> > 
> > diff --git a/docs/formatdomain.rst b/docs/formatdomain.rst
> > index de085f616a..5e0019c574 100644
> > --- a/docs/formatdomain.rst
> > +++ b/docs/formatdomain.rst
> 
> [...]
> 
> > @@ -699,6 +700,10 @@ host/guest with many LUNs. :since:`Since 1.2.8 (QEMU only)`
> >     The element has two optional attributes ``pool_min`` and ``pool_max`` which
> >     allow setting lower and upper boundary for number of worker threads for
> >     given IOThread. :since:`Since 8.4.0`
> > +``mainloop``
> > +   The optional ``mainloop`` element contains two optional attributes
> > +   ``pool_min`` and ``pool_max`` which allow setting lower and upper boundary
> > +   for number of worker threads for the main event loop. :since:`Since 8.4.0`
> 
> I don't think we should use the qemu term "main loop" here. In general
> we refer to the qemu process as emulator, including stuff like
> emulatorpin and similar.

It isn't even especially part of the QEMU main loop IIUC.

Rather it is setting up a pool of threads that are used
for serving I/O, when no specific I/O thread is configurd
for the guest.

Perhaps it can be '<defaultiothread/>' or something along
those lines, to make it clear it is an I/O related tunable.


With regards,
Daniel
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