Re: Autobuilder reproducibility target changes


Richard Purdie
 

On Sun, 2021-02-14 at 13:17 -0600, Joshua Watt wrote:
On Sun, Feb 14, 2021 at 6:19 AM Richard Purdie
<richard.purdie@linuxfoundation.org> wrote:

Regular users of the autobuilder will note that I've split the
reproducible builds test out of the main oe-selftest build and into its
own target build. This is because that test tends to run for a lot
longer time period and it helps to see the result separately.

I've only done this for master. If gatesgarth and dunfell want to
follow, that should be straight forward with a change to the branch in
autobuilder-helper. Obviously we should ensure this is working ok with
master first but so far so good.

It has already highlighted the difference between a successful run:

https://autobuilder.yoctoproject.org/typhoon/#/builders/115/builds/2
https://autobuilder.yoctoproject.org/typhoon/#/builders/119/builds/2
(took 3-4 hours)

and failing two failing runs:

https://autobuilder.yoctoproject.org/typhoon/#/builders/116/builds/2
https://autobuilder.yoctoproject.org/typhoon/#/builders/118/builds/2
(took 9 hours)
OK, I read through the code and unfortunately found a bug: when
attempting to make sure the "B" build doesn't use sstate, I misspelled
the SSTATE_MIRRORS, which means that the B build could have been
pulling from the sstate mirror when it was not supposed to. This has a
few implications:

 1) It might explain why some of the reproducible results seem intermittent
 2) It might explain why there is such a time disparity between the tests
The "good" news is that this didn't affect the autobuilder as it sets
SSTATE_DIR to a common directory and doesn't use SSTATE_MIRRORS.

Unfortunately, while it probably will help the intermittent results,
it probably means that the tests taking 9 hours is what is "supposed"
to happen, and they happen to be shorter sometimes because the B build
is pulling from sstate when it's not supposed to.
I don't think we're to the bottom of this. If its not spending the time
in diffoscope, something seems to cause builds with differences to take
much longer...

Cheers,

Richard

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