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

On Mon, Mar 30, 2020 at 02:11:29PM +0200, Andrea Bolognani wrote: > 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 a libvirt.git compile but small enough that outdated cruft gets purged 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. Ok, I'll see if I can get some usage stats out of ccache for our CI jobs on GitLab. > 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. True, but I imagine in terms of object size all the other projects probably barely reach 5% of the main libvirt.git build size, so likely lost in the noise.