Performance increase for Koji builders

[Mike McLean]

On 05/28/2015 03:41 PM, Jason L Tibbitts III wrote:
>>>>>> "MS" == Miroslav Suchy <msuchy at redhat.com> writes:
>
> MS> The performance increase is huge and I believe Koji can do the same.
>
> I have always done my local mock builds in tmpfs and indeed the
> performance increase is huge.  There were, however, odd problems in the
> past with tmpfs not supporting some necessary features (like
> capabilities, I think) which would get in the way of using it for
> everything.  I don't know if that's solved now, and particularly if it's
> solved on whatever OS our builders run currently.

Also, some builders do not necessarily have a lot of ram. Some 
buildroots are large, some sources are extremely large (e.g. texlive). 
If we do this, it will need to be configurable, probably per-package or 
per-tag.


from https://www.kernel.org/doc/Documentation/filesystems/tmpfs.txt
> size:      The limit of allocated bytes for this tmpfs instance. The
>            default is half of your physical RAM without swap. If you
>            oversize your tmpfs instances the machine will deadlock
>            since the OOM handler will not be able to free that memory.

"machine will deadlock" does not sound promising


Note that it should be possible to enable the tmpfs plugin in 
default.cfg on koji builders if folks want to play around with this. The 
mock configs that koji writes do not say anything about the tmpfs plugin.