On Tue, Jun 07, 2022 at 10:06:16AM +0200, Michal Prívozník wrote: > On 6/6/22 13:40, Daniel P. Berrangé wrote: > > 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@xxxxxxxxxx> > >>> --- > >>> 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. > > Right, I'd rather avoid putting it as an attribute to <emulator/> since > we have a whole section dedicated to performance tuning. Not to mention > <emulator/> lives under <devices/> and I don't think we put performance > related knobs there. I didn't object to Peter's suggestion because I > don't have better idea. > > So are you suggesting that <defaultiothread/> would be at the same level > as <iothreads/> and <iothreadids/> or it would be nested somewhere? > > <domain> > <name/> > <iothreads>4</iothreads> > <iothreadids> > <iothread id="1" thread_pool_min="2" thread_pool_max="8"/> > <iothread id="2"/> > <iothreadids> > <defaultiothread thread_pool_min="8" thread_pool_max="8"/> > <devices/> > </domain> Yeah, that's pretty much what I was implying. With regards, Daniel -- |: https://berrange.com -o- https://www.flickr.com/photos/dberrange :| |: https://libvirt.org -o- https://fstop138.berrange.com :| |: https://entangle-photo.org -o- https://www.instagram.com/dberrange :|
