Re: [PATCH v3 4/4] tests/qtest/migration: add postcopy test with multifd

[Peter Xu <peterx@redhat.com>]

On Wed, Jan 22, 2025 at 01:26:21PM +0530, Prasad Pandit wrote:
> Hi,
> On Tue, 21 Jan 2025 at 21:17, Peter Xu <peterx@redhat.com> wrote:
> > https://lore.kernel.org/qemu-devel/ZykJBq7ME5jgSzCA@x1n/
> > Would you please add all the tests mentioned there?
> 
>     /x86_64/migration/multifd/file/mapped-ram/
>     /x86_64/migration/multifd/tcp/uri/plain/none
>     /x86_64/migration/multifd/tcp/plain/cancel
> 
>     /x86_64/migration/postcopy/plain
>     /x86_64/migration/postcopy/recovery/
>     /x86_64/migration/postcopy/preempt/
> 
> * Of the tests you suggested above, I'll try to enable multifd
> channels for 'postcopy/recovery' and 'postcopy/preempt' tests. For the
> 'multifd' tests above, how do we want to modify them? Enable
> 'postcopy' mode for them?

Right, that implies a migration with both features enabled but finished
even before postcopy starts.

We have some tricky paths that may go differently when different feature
enabled, especially when it's relevant to postcopy and multifd.  Adding
these tests could make sure those corner cases got covered.

And btw, some of my above lines are not a single test, but a set of tests.
E.g., "/x86_64/migration/postcopy/recovery/" is not a single test but:

        # /x86_64/migration/postcopy/recovery/plain
        # /x86_64/migration/postcopy/recovery/tls/psk
        # /x86_64/migration/postcopy/recovery/double-failures/handshake
        # /x86_64/migration/postcopy/recovery/double-failures/reconnect

Let me list all the tests that is relevant to the two features to be
explicit..

        # /x86_64/migration/postcopy/plain
        # /x86_64/migration/postcopy/suspend
        # /x86_64/migration/postcopy/tls/psk
        # /x86_64/migration/postcopy/recovery/plain
        # /x86_64/migration/postcopy/recovery/tls/psk
        # /x86_64/migration/postcopy/recovery/double-failures/handshake
        # /x86_64/migration/postcopy/recovery/double-failures/reconnect
        # /x86_64/migration/postcopy/preempt/plain
        # /x86_64/migration/postcopy/preempt/tls/psk
        # /x86_64/migration/postcopy/preempt/recovery/plain
        # /x86_64/migration/postcopy/preempt/recovery/tls/psk
        # /x86_64/migration/multifd/tcp/tls/psk/match
        # /x86_64/migration/multifd/tcp/tls/psk/mismatch
        # /x86_64/migration/multifd/tcp/tls/x509/default-host
        # /x86_64/migration/multifd/tcp/tls/x509/override-host
        # /x86_64/migration/multifd/tcp/tls/x509/mismatch-host
        # /x86_64/migration/multifd/tcp/tls/x509/allow-anon-client
        # /x86_64/migration/multifd/tcp/tls/x509/reject-anon-client
        # /x86_64/migration/multifd/tcp/plain/zstd
        # /x86_64/migration/multifd/tcp/plain/zlib
        # /x86_64/migration/multifd/tcp/plain/cancel
        # /x86_64/migration/multifd/tcp/plain/zero-page/legacy
        # /x86_64/migration/multifd/tcp/plain/zero-page/none
        # /x86_64/migration/multifd/tcp/uri/plain/none
        # /x86_64/migration/multifd/tcp/channels/plain/none

(I used to reference mapped-ram for multifd, but I just remembered it can't
be enabled with postcopy, so I dropped them)

I believe many of the tests can be avoided, but still below is a list of
minimum tests that I think might still be good to add:

        # /x86_64/migration/postcopy/plain
        # /x86_64/migration/postcopy/recovery/tls/psk
        # /x86_64/migration/postcopy/preempt/plain
        # /x86_64/migration/postcopy/preempt/recovery/tls/psk
        # /x86_64/migration/multifd/tcp/tls/psk/match
        # /x86_64/migration/multifd/tcp/plain/zstd
        # /x86_64/migration/multifd/tcp/plain/cancel

I kept almost tls relevant ones because it has the most code path coverage,
and I suppose tls should also be an emphasis in the future for migration in
CoCo environments.  I removed most of the trivial test cases, like postcopy
double failures etc. which can be too hard to trigger in real life.

Feel free to comment on whether you think the list is suitable to you.  If
you want to add some more into the list I'm also ok with.

IMHO we can have a specific path "/x86_64/migration/multifd+postcopy/*" for
all above new tests, that have both features enabled.

Fabiano, you're rethinking the test infra, please comment if you have any
thoughts on above too.

Thanks,

-- 
Peter Xu