Re: [PATCH v3 8/9] tests/qtest: make more migration pre-copy scenarios run non-live

[Daniel P . Berrangé]

On Thu, Jun 01, 2023 at 02:33:56PM +0200, Juan Quintela wrote:
> Daniel P. Berrangé <berrange@redhat.com> wrote:
> > There are 27 pre-copy live migration scenarios being tested. In all of
> > these we force non-convergance and run for one iteration, then let it
> > converge and wait for completion during the second (or following)
> > iterations. At 3 mbps bandwidth limit the first iteration takes a very
> > long time (~30 seconds).
> >
> > While it is important to test the migration passes and convergance
> > logic, it is overkill to do this for all 27 pre-copy scenarios. The
> > TLS migration scenarios in particular are merely exercising different
> > code paths during connection establishment.
> >
> > To optimize time taken, switch most of the test scenarios to run
> > non-live (ie guest CPUs paused) with no bandwidth limits. This gives
> > a massive speed up for most of the test scenarios.
> >
> > For test coverage the following scenarios are unchanged
> >
> >  * Precopy with UNIX sockets
> >  * Precopy with UNIX sockets and dirty ring tracking
> >  * Precopy with XBZRLE
> >  * Precopy with UNIX compress
> >  * Precopy with UNIX compress (nowait)
> >  * Precopy with multifd
> >
> > On a test machine this reduces execution time from 13 minutes to
> > 8 minutes.
> >
> > Signed-off-by: Daniel P. Berrangé <berrange@redhat.com>
> 
> Hi
> 
> I have a different idea to get the migration tests faster.  Namely, just
> stop letting enter the completation stage until we are ready to use it.

That is still going to be slower than running the migration non-live,
because the guest will be dirtying memory that needs to be transferred.
Even if we have the elevated bandwidth limit that's going to have a
CPU cost which will hurt running time in CI where alot is running in
parallel.

> I need that functionality also for vfio migration, so as I have to
> create the patches, can we put on hold the last two patches and give me
> a couple of days?

IMHO this patch is beneficial regardless.

The next patch might be redundant though.


With regards,
Daniel
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