[ccache] memcached with ccache

[Pierre Tardy]

Hi,
I updated the pull request, with code that makes it have similar
performance as with fs:

  cold fsccache
    real        0m3.820s
    user        0m2.956s
    sys 0m0.544s

    hot fsccache
    real        0m0.204s
    user        0m0.076s
    sys 0m0.048s

    cold memccached
    real        0m3.813s
    user        0m2.880s
    sys 0m0.576s

    hot memccached
    real        0m0.285s
    user        0m0.136s
    sys 0m0.072s


Please note that this mode is only useful when running ccache in lots of
servers which are sharing their cache in a memcached cluster (typically run
on the same servers)
This is supposed to increase the overall hitrate, as there will always be
another server that already compiled the same file.

For this usecase, ccache doc recommend to share the ccache db via NFS,
which is obviously less efficient in term of scalability. There is no more
the one nfs server bottleneck.

Tomorrow, I'll run more bench with building Android.

Regards,
Pierre


On Thu, Jun 20, 2013 at 11:03 PM, Pierre Tardy <tardyp at gmail.com> wrote:

> Hi,
> Back in 2010, there has been some question about supporting memcached as a
> backend for ccache:
> https://lists.samba.org/archive/ccache/2010q4/000686.html
>
>
> Looks like this thread hasn't result in code, and I did take a few days to
> make an attempt at it.
>
> Here is the first working code:
> https://github.com/jrosdahl/ccache/pull/30
>
> Very first bench on my laptop is:
> self compiling ccache:
> 200ms with fs
> 800ms with memcached
>
> I'll make more bench on our cluster in the next few days.
>
> Regards,
> Pierre
>