Re: [PATCH 2/2] tests/qtest: make more migration pre-copy scenarios run non-live

[Juan Quintela]

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 multifd

Just for completeness: the other test that is still slow is
/migration/vcpu_dirty_limit.

> -    migrate_ensure_non_converge(from);
> +    if (args->live) {
> +        migrate_ensure_non_converge(from);
> +    } else {
> +        migrate_ensure_converge(from);
> +    }

Looks ... weird?
But the only way that I can think of improving it is to pass args to
migrate_ensure_*() and that is a different kind of weird.

>      } else {
> -        if (args->iterations) {
> -            while (args->iterations--) {
> +        if (args->live) {
> +            if (args->iterations) {
> +                while (args->iterations--) {
> +                    wait_for_migration_pass(from);
> +                }
> +            } else {
>                  wait_for_migration_pass(from);
>              }
> +
> +            migrate_ensure_converge(from);

I think we should change iterations to be 1 when we create args, but
otherwise, treat 0 as 1 and change it to something in the lines of:

        if (args->live) {
            while (args->iterations-- >= 0) {
                wait_for_migration_pass(from);
            }
            migrate_ensure_converge(from);

What do you think?


> -        qtest_qmp_eventwait(to, "RESUME");
> +        if (!args->live) {
> +            qtest_qmp_discard_response(to, "{ 'execute' : 'cont'}");
> +        }
> +        if (!got_resume) {
> +            qtest_qmp_eventwait(to, "RESUME");
> +        }
>  
>          wait_for_serial("dest_serial");
>      }

I was looking at the "culprit" of Lukas problem, and it is not directly
obvious.  I see that when we expect one event, we just drop any event
that we are not interested in.  I don't know if that is the proper
behaviour or if that is what affecting this test.

Later, Juan.