[libvirt-jenkins-ci PATCH 2/7] lcitool: Configure ccache using environment variables

[Andrea Bolognani]

On Mon, 2020-03-30 at 12:45 +0100, Daniel P. Berrangé wrote:
> On Fri, Mar 27, 2020 at 08:34:54PM +0100, Andrea Bolognani wrote:
> > +export CCACHE_MAXSIZE="2G"
> 
> I was wondering what a good size for ccache would be. Is there any history
> to why we picked 2G ?  Having it too big didn't really matter for the
> Jenkins builders as it is kept local.  For GitLab the cache is downloaded
> at start of the job off cloud cstorage. So we want it large enough to fit
> a libvirt.git compile but small enough that outdated cruft gets purged
> reasonably quickly, so we don't waste time in GitLab CI downloading GB's
> of data that is no longer needed in the cache.
> 
> NB, this is NOT an objection to this patch, as 2GB is a pre-existing value
> we used. Just want to know how we should consider tuning it in future.

I think we just scaled it down (from the default of 5 GiB) so that
it would use most of the disk space that remained free in the VM's
15 GiB disk, while leaving some leeway to allow for repositories to
grow. Nothing more scientific than that, I'm afraid.

Note that, for VMs, we're building not just libvirt but a bunch of
other projects, so if we wanted to tweak it we'd have to take that
into account as well and not size it for just libvirt itself.

-- 
Andrea Bolognani / Red Hat / Virtualization