Re: [kernelci-members] Working with the KernelCI project

Nikolai Kondrashov
2020-10-01T10:51:28Z

On 10/1/20 11:43 AM, Dmitry Vyukov wrote:
> On Thu, Oct 1, 2020 at 10:30 AM Nikolai Kondrashov
> <Nikolai.Kondrashov@redhat.com> wrote:
>>
>> On 9/30/20 10:07 AM, Dmitry Vyukov wrote:
>> > On Tue, Sep 29, 2020 at 7:13 PM Nikolai Kondrashov
>> > <Nikolai.Kondrashov@redhat.com> wrote:
>> >> Regarding bisection results I was hoping we could represent that data
>> >> implicitly. I.e. by having information about which 'revision' comes after
>> >> which, and executing a query to find a pair of adjacent revisions one of which
>> >> has the bug and another doesn't. In theory that should be possible, but in
>> >> practice... well, you know :) If that fails, we can attach that data
>> >> explicitly somewhere. Or we can simply start with that to have it faster.
>> >
>> > Humm... interesting. I guess it can work. We could mark the issue as
>> > happening on the cause commit and as not happening on the previous
>> > commit.
>> > However, one problem is that we don't keep info about the previous
>> > commit as of now, we only store the root cause commit in the database.
>>
>> Something has to maintain the information on history connectivity, and so far
>> the plan was to let the submitting system do it. E.g. refer to a clone of the
>> repo they're testing. There's definitely more research and design to be done.
>>
>> However, you should've been testing the previous commit to be able to find the
>> root cause commit? Shouldn't you?
>
> We do. But that happens in a very different part of the system and
> that info is not kept in a structured form because it's not useful for
> anything in our system.
>
> Well, it actually turned out that it's not necessary to test all of
> the parents of a commit during bisection to point at a particular
> commit in some interesting git tree topologies.

Ah, I see I'll need to ask you more questions about bisections once we get to
that :)

>> > Another is that in git it's possible to have several preceding
>> > commits.
>>
>> Right, I didn't think through that yet. We might need a separate history link
>> object, then. Do you know if a commit can have more than two parents?
>
> Octopus merge commits can have lots of parents.

Right, I forgot about those.

Thank you!
Nick