Bug#976932: gnome-photos: FTBFS on machines with more than 128 cores

[Lucas Nussbaum]

Hi,

On 09/12/20 at 09:59 +0000, Simon McVittie wrote:
> Control: retitle -1 gnome-photos: FTBFS on machines with more than 128 cores
> 
> On Wed, 09 Dec 2020 at 09:35:05 +0100, Lucas Nussbaum wrote:
> > During a rebuild of all packages in sid, your package failed to build
> > on ppc64el. At the same time, it did not fail on amd64.
> >
> > > 	cd obj-powerpc64le-linux-gnu && LC_ALL=C.UTF-8 ninja -j160 -v
> 
> Is this a 160-CPU machine?! (Or maybe 80- or 40-CPU with hyperthreading?)

It's 2 CPUs, 10 cores per CPU, 8 threads per core
(https://en.wikipedia.org/wiki/POWER8)

(So it's kind-of artificially large due to SMT)

> > > Bail out! GLib-GObject-FATAL-WARNING: value "80" of type 'gint' is invalid or out of range for property 'threads' of type 'gint'
> 
> 80 does seem like a lot of threads, although it also seems weird to have an
> arbitrary limit.
> 
> libgegl has a GeglConfig singleton object with a "threads" property, whose
> maximum value is an arbitrary constant GEGL_MAX_THREADS.
> 
> gnome-photos sets "threads" to half the number of CPU cores available,
> which is entirely reasonable for desktop-class hardware, but is not going
> to work on something massively-parallel.
> 
> Can you test-build a fix on similar hardware? Oddly enough I don't have a
> machine with this many cores conveniently available :-)

Sure!

Lucas