[ccache] useful test package to use with ccache at the outset in Gentoo.....

Michael Fothergill michael.fothergill at gmail.com
Fri Dec 8 13:03:42 UTC 2017


On 8 December 2017 at 01:35, Scott Bennett via ccache <
ccache at lists.samba.org> wrote:

> Michael Fothergill via ccache <ccache at lists.samba.org> wrote:
>
> > I have an amd64 kaveri box with 8GB RAM and run Gentoo stable on it.
> >
> > I have just installed ccache with 2GB memory allocated to it.
>
>      By that, I assume you have allocated some kind of memory-based device
> for the cache.  Is that a correct understanding?
>

​Thanks for your reply and comments.  I am assuming that by having the
standard command ​

​CCACHE_SIZE="4G" (I have increased the allocation)
then memory from the hard drive is being used by default here - I was not
trying to use e.g. RAM memory.

>
> > I have tried some repeat compilations to see if there would be any speed
> > increase.
> >
> > So far I have not seen much change but I am not skilled enough to improve
> > things yet.
>
>      Your statistics show that slightly more than 45% of your total
> compiler invocations (hits/(hits+misses)) were avoided.  Did that not
> make a dent in your timings?
> >
> > I tried compiling gcc, glibc and imagemagick but did not see much
> > improvement.
>
>      If you run the full build process for gcc, I would not expect
> to see much improvement because most of it involves the use of either
> a) a temporarily built compiler in a temporary location or b) the
> newly built compiler being used for testing, but not yet installed
> into the production location on your system.
>

​Would cachecc1 perform any better with gcc?​



>      ImageMagick and GraphicsMagick both should provide useful timings
> and ccache statistics.  glibc probably would, too, though it's not
> nearly as big.  I don't know what sort of build procedures Gentoo uses,
> but from the FreeBSD ports tree, here are some other good examples of
> test cases:  math/octave, www/webkit-gtk2, www/webkit-gtk3,
> www/webkit2-gtk3, devel/llvm40.  Be prepared to wait a long time for
> the first compilation of each of the webkits.  They are big and slow
> to compile and, in the past, have shown instabilities in their build
> procedures when parallel make runs were used.
>

​I have now compiled qtwebengine, libreoffice and and dramatically reduced
the compile time with ccache
now I am using the 3.3.4 version of the program ( see here
https://forums.gentoo.org/viewtopic-t-1073298.html
​ ). I think the earlier version of ccache was not working properly.

People on the thread have suggested that maybe cachecc1 might not work so
well with gcc in practice and I should stick
with ccache as is.

But you may take a different view.  ​



> YMMV on another OS.
>      One big savings for me was in running "make buildworld" and "make
> buildkernel".  buildworld, on my last machine, was taking about six
> hours elapsed time for a first run.  When running it later after
> updating the source tree, the elapsed time was reduced by 2/3 to 3/4,
> depending upon the number and sizes of source modules affected by the
> updates.
>

​These sound like the emerge --ask --update --deep @world command used in
Gentoo (and similar versions).​

​It's not time to update the system again yet but I think that it could
well speed things up as long as the cache size is big enough for a lot of
packages (e.g. 200 plus)

Thanks and comments appreciated.

Michael Fothergill​



> Note that ccache and some other things need a slightly
> different setup in order to build FreeBSD.  Your OS may also need some
> special provision, so be sure to read the ccache installation
> instructions for Gentoo carefully.
>
>
>                                   Scott Bennett, Comm. ASMELG, CFIAG
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