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Re: [PATCH RFC 3/3] qtest/migration: Use switchover-hold to speedup
From: |
Peter Xu |
Subject: |
Re: [PATCH RFC 3/3] qtest/migration: Use switchover-hold to speedup |
Date: |
Fri, 2 Jun 2023 09:23:59 -0400 |
On Fri, Jun 02, 2023 at 12:03:05PM +0100, Daniel P. Berrangé wrote:
> On Thu, Jun 01, 2023 at 09:16:26PM -0400, Peter Xu wrote:
> > Use the switchover-hold flag rather than tuning bw+downtime to guide test
> > convergence.
> >
> > This can achieve similar goal of previous patch "tests/qtest: massively
> > speed up migration-test" but without magic offset to write or monitoring.
> >
> > The initial solution can reduce migration-test time from 8min to 1min40s,
> > this patch can further reduce it from 1m40s to 1m1s per my local test.
> >
> > Signed-off-by: Peter Xu <peterx@redhat.com>
> > ---
> > tests/qtest/migration-test.c | 20 ++++++++++++++------
> > 1 file changed, 14 insertions(+), 6 deletions(-)
> >
> > diff --git a/tests/qtest/migration-test.c b/tests/qtest/migration-test.c
> > index b0c355bbd9..62bdd67fd9 100644
> > --- a/tests/qtest/migration-test.c
> > +++ b/tests/qtest/migration-test.c
> > @@ -433,16 +433,15 @@ static void migrate_set_parameter_bool(QTestState
> > *who, const char *parameter,
> >
> > static void migrate_ensure_non_converge(QTestState *who)
> > {
> > - /* Can't converge with 1ms downtime + 3 mbs bandwidth limit */
> > - migrate_set_parameter_int(who, "max-bandwidth", 3 * 1000 * 1000);
> > - migrate_set_parameter_int(who, "downtime-limit", 1);
> > + /* Hold off switchover for precopy only */
> > + migrate_set_parameter_bool(who, "switchover-hold", true);
> > }
> >
> > static void migrate_ensure_converge(QTestState *who)
> > {
> > - /* Should converge with 30s downtime + 1 gbs bandwidth limit */
> > - migrate_set_parameter_int(who, "max-bandwidth", 1 * 1000 * 1000 *
> > 1000);
> > - migrate_set_parameter_int(who, "downtime-limit", 30 * 1000);
> > + /* No limitation on bandwidth so converge faster */
> > + migrate_set_parameter_int(who, "max-bandwidth", 0);
>
> You're already setting max-bandwith==0 in migrate_postcopy_prepare.
>
> If you also set it in test_precopy_common, so we don't need to
> set it here, and we'll avoid the initial phase running with
> bandwidth=32mbs.
There are more tests than test_precopy_common() that leverages this, so I
used to kept it there to still share some code:
test_migrate_auto_converge[2021] migrate_ensure_converge(from);
test_multifd_tcp_cancel[2349] migrate_ensure_converge(from);
But I think you're right - moving the bw=0 setup out should be cleaner.
I'll see whether I should just move it into all the specific tests.
Thanks,
--
Peter Xu