Re: [PATCH] Revert "tests/migration: Reduce autoconverge initial bandwidth"

[Thomas Huth]

On 24/06/2020 18.26, Philippe Mathieu-Daudé wrote:
> Hi Thomas,
>
> On 6/24/20 12:21 PM, Philippe Mathieu-Daudé wrote:
> > On 6/24/20 7:04 AM, Thomas Huth wrote:
> > > On 23/06/2020 19.35, Philippe Mathieu-Daudé wrote:
> > > > On 6/23/20 7:07 PM, Thomas Huth wrote:
> > > > > On 23/06/2020 17.39, Philippe Mathieu-Daudé wrote:
> > > > > > On 6/23/20 4:56 PM, Michael S. Tsirkin wrote:
> > > > > > > This reverts commit 6d1da867e65f ("tests/migration: Reduce autoconverge initial 
> > > > > > > bandwidth")
> > > > > > > since that change makes unit tests much slower for all developers, while it's 
> > > > > > > not
> > > > > > > a robust way to fix migration tests. Migration tests need to find
> > > > > > > a more robust way to discover a reasonable bandwidth without slowing
> > > > > > > things down for everyone.
> > > > > >
> > > > > > Please also mention we can do this since 1de8e4c4dcf which allow
> > > > > > marked the s390x job as "unstable" and allow it to fail.
> > > > > >
> > > > > > But if nobody is going to look at it, instead lets disable
> > > > > > it until someone figure out the issue:
> > > > > >
> > > > > > -- >8 --
> > > > > > diff --git a/.travis.yml b/.travis.yml
> > > > > > index 74158f741b..364e67b14b 100644
> > > > > > --- a/.travis.yml
> > > > > > +++ b/.travis.yml
> > > > > > @@ -507,6 +507,7 @@ jobs:
> > > > > >
> > > > > >       - name: "[s390x] Clang (disable-tcg)"
> > > > > >         arch: s390x
> > > > > > +      if: false # Temporarily disabled due to issue testing migration
> > > > > > (see commit 6d1da867e65).
> > > > > >         dist: bionic
> > > > > >         compiler: clang
> > > > > >         addons:
> > > > >
> > > > > Sorry, but that looks wrong. First, the disable-tcg test does not run
> > > > > the qtests at all. So this is certainly the wrong location here.
> > > >
> > > > Indeed, this is the previous job:
> > > >
> > > > -- >8 --
> > > > diff --git a/.travis.yml b/.travis.yml
> > > > index 74158f741b..b399e20078 100644
> > > > --- a/.travis.yml
> > > > +++ b/.travis.yml
> > > > @@ -464,6 +464,7 @@ jobs:
> > > >           - CONFIG="--disable-containers
> > > > --target-list=ppc64-softmmu,ppc64le-linux-user"
> > > >
> > > >       - name: "[s390x] GCC check-tcg"
> > > > +      if: false # Temporarily disabled due to issue testing migration
> > > > (see commit 6d1da867e65).
> > > >         arch: s390x
> > > >         dist: bionic
> > > >         addons:
> > > > ---
> > > >
> > > > > Second,
> > > > > if just one of the qtests is failing, please only disable that single
> > > > > failing qtest and not the whole test pipeline.
> > > >
> > > > Last time we talked about this Dave was against that option:
> > > >
> > > > https://www.mail-archive.com/qemu-devel@nongnu.org/msg690085.html
> > >
> > > Was he? Citing his reply to the mail from your URL:
> > >
> > >   "Before we take the hammer to it, could you try reducing it's initial
> > > bandwidth"
> > >
> > > So all I can see is that he first wanted to try something different than
> > > disabling the test. And now,  instead of using a small hammer to disable
> > > just this test, you now even use a very *big* hammer to disable *all*
> > > tests. That's just a very bad idea. Please don't.
>
> You asked on IRC the CI failures history:
>
> https://travis-ci.org/github/philmd/qemu/jobs/663607963
> https://travis-ci.org/github/philmd/qemu/jobs/663622229
> https://travis-ci.org/github/philmd/qemu/jobs/663642522
>
> "No output has been received in the last 10m0s, this potentially
> indicates a stalled build or something wrong with the build itself."

Ok, but none of these hangs seem to be related to the migration test. I 
assume that's just a generic unreliability of the builder machines, 
which should have been addresses with Alex' patch 1de8e4c4dcf2af8e1 ?

 Thomas