Re: [PATCH v3 4/6] gitlab-ci: Add ccache in $PATH and display statistics

[Daniel P . Berrangé]

On Fri, May 21, 2021 at 12:48:21PM +0200, Thomas Huth wrote:
> On 20/05/2021 13.27, Philippe Mathieu-Daudé wrote:
> > +Stefan/Daniel
> > 
> > On 5/20/21 10:02 AM, Thomas Huth wrote:
> > > On 19/05/2021 20.45, Philippe Mathieu-Daudé wrote:
> > > > If a runner has ccache installed, use it and display statistics
> > > > at the end of the build.
> > > > 
> > > > Signed-off-by: Philippe Mathieu-Daudé <f4bug@amsat.org>
> > > > ---
> > > >    .gitlab-ci.d/buildtest-template.yml | 5 +++++
> > > >    1 file changed, 5 insertions(+)
> > > > 
> > > > diff --git a/.gitlab-ci.d/buildtest-template.yml
> > > > b/.gitlab-ci.d/buildtest-template.yml
> > > > index f284d7a0eec..a625c697d3b 100644
> > > > --- a/.gitlab-ci.d/buildtest-template.yml
> > > > +++ b/.gitlab-ci.d/buildtest-template.yml
> > > > @@ -6,13 +6,18 @@
> > > >          then
> > > >            JOBS=$(sysctl -n hw.ncpu)
> > > >            MAKE=gmake
> > > > +        PATH=/usr/local/libexec/ccache:$PATH
> > > >            ;
> > > >          else
> > > >            JOBS=$(expr $(nproc) + 1)
> > > >            MAKE=make
> > > > +        PATH=/usr/lib/ccache:/usr/lib64/ccache:$PATH
> > > 
> > > That does not make sense for the shared runners yet. We first need
> > > something to enable the caching there - see my series "Use ccache in the
> > > gitlab-CI" from April (which is currently stalled unfortunately).
> > 
> > TL;DR: I don't think we should restrict our templates to shared runners.
> 
> I'm certainly not voting for restricting ourselves to only use shared
> runners here - but my concern is that this actually *slows* down the shared
> runners even more! (sorry, I should have elaborated on that in my previous
> mail already)
> 
> When I was experimenting with ccache in the shared runners, I saw that the
> jobs are running even slower with ccache enabled as long as the cache is not
> populated yet. You only get a speedup afterwards. So if you add this now
> without also adding the possibility to store the cache persistently, the
> shared runners will try to populate the cache each time just to throw away
> the results afterwards again. Thus all the shared runners only get slower
> without any real benefit here.
> 
> Thus we either need to get ccache working properly for the shared runners
> first, or you have to think of a different way of enabling ccache for the
> non-shared runners, so that it does not affect the shared runners
> negatively.

Is there anything functional holding up your previous full cccache support
series from last month ? Or is it just lack of reviews ?

Regards,
Daniel
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