qa: synchronize kcephfs suites with fs/multimds

[batrick]

Fixes: http://tracker.ceph.com/issues/22627

Signed-off-by: Patrick Donnelly pdonnell@redhat.com

[batrick]

@ukernel qa/cephfs/clusters/1-mds-4-client.yaml places 2 clients on the same machine, do you know if that would cause a problem for the kclient testing?

Also, the qa/cephfs/clusters/1-mds-*-client.yaml now colocate 1 client with the osds/mdss to reduce the number of machines required for testing. Do you forsee problems with that? I ask because I've been told at least OSD full testing can result in weird deadlocks when the kernel client is also on the same machine.

[ukernel]

kernel mount and OSDs on the same machine can cause memory allocation deadlock. (OSD allocates memory from kernel. To satisfy the memory allocation, kernel flushes dirty data in cephfs and sends requests to the OSD)

For multiple kernel mounts on the same machine, I think the main problem is that killing kernel mount requires rebooting machine. If a test kills a mount, all mounts on that machine disappear.

Putting kernel mount and ceph daemons on the same machine has similar issue.

I think only tests in qa/tasks/cephfs kill mount. Maybe we can give these tests a separate cluster config

[batrick]

Great, thanks for explaining!

[ukernel]

LGTM