[PATCH 0/2] tests/migration: Fix migration-test slowdown

[Juan Quintela]

Since commit:

commit 1bfc8dde505f1e6a92697c52aa9b09e81b54c78f
Author: Dr. David Alan Gilbert <dgilbert@redhat.com>
Date:   Mon Mar 6 15:26:12 2023 +0000

    tests/migration: Tweek auto converge limits check

    Thomas found an autoconverge test failure where the
    migration completed before the autoconverge had kicked in.
    [...]

migration-test has become very slow.
On my laptop, before that commit migration-test takes 2min10seconds
After that commit, it takes around 11minutes

We can't revert it because it fixes a real problem when the host
machine is overloaded.  See the comment on test_migrate_auto_converge().

So I did two things here:

- Once that we have setup up precopy, we can move to full speed, no
  need to continue at 3MB/s.  That slowed everything a lot.

- Only run auto_converge tests when we are asking for slow tests.

  Only that test on my hardware requires more than 1min to run.  We
  need to run it at 3MB/s, but we are asking it to do 15 iterations
  throgh 150MB of RAM.  We can have a test that is (reasonably) fast,
  or one that also works when machine is very loaded.

To test that things still works over load, I used my desktop (ancient
core i9900), and run migration-test in a loop in 20 terminals (load
was 40) and didn't see a single failure in more than 1 hour run.

Please, review.

PD.  Yes, I am still looking at the dreaded multifd_cancel test, but
even on this setup, I am unable to get a failure.  I have never seen a
failure on it when I am running it, but I am only running x86 kvm
linux.  Moving to arm or tcg and see how well that goes.

Juan Quintela (2):
  tests/migration: Make precopy fast
  tests/migration: Only run auto_converge in slow mode

 tests/qtest/migration-test.c | 26 ++++++++++++++++++++++----
 1 file changed, 22 insertions(+), 4 deletions(-)

-- 
2.39.2