From ce508a3c29c2fdaeea785a00abcf35cf90da7c2d Mon Sep 17 00:00:00 2001 From: Stefan Hajnoczi Date: Mon, 12 Apr 2021 15:34:37 +0100 Subject: [PATCH] docs/devel/qgraph: add troubleshooting information It can be tricky to troubleshoot qos-test when a test won't execute. Add an explanation of how to trace qgraph node connectivity and find which node has the problem. Signed-off-by: Stefan Hajnoczi Message-Id: <20210412143437.727560-3-stefanha@redhat.com> Acked-by: Paolo Bonzini Signed-off-by: Thomas Huth --- docs/devel/qgraph.rst | 58 +++++++++++++++++++++++++++++++++++++++++++ 1 file changed, 58 insertions(+) diff --git a/docs/devel/qgraph.rst b/docs/devel/qgraph.rst index a9aff167ad..318534d4b0 100644 --- a/docs/devel/qgraph.rst +++ b/docs/devel/qgraph.rst @@ -92,6 +92,64 @@ The basic framework steps are the following: Depending on the QEMU binary used, only some drivers/machines will be available and only test that are reached by them will be executed. +Troubleshooting unavailable tests +^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ +If there is no path from an available machine to a test then that test will be +unavailable and won't execute. This can happen if a test or driver did not set +up its qgraph node correctly. It can also happen if the necessary machine type +or device is missing from the QEMU binary because it was compiled out or +otherwise. + +It is possible to troubleshoot unavailable tests by running:: + + $ QTEST_QEMU_BINARY=build/qemu-system-x86_64 build/tests/qtest/qos-test --verbose + # ALL QGRAPH EDGES: { + # src='virtio-net' + # |-> dest='virtio-net-tests/vhost-user/multiqueue' type=2 (node=0x559142109e30) + # |-> dest='virtio-net-tests/vhost-user/migrate' type=2 (node=0x559142109d00) + # src='virtio-net-pci' + # |-> dest='virtio-net' type=1 (node=0x55914210d740) + # src='pci-bus' + # |-> dest='virtio-net-pci' type=2 (node=0x55914210d880) + # src='pci-bus-pc' + # |-> dest='pci-bus' type=1 (node=0x559142103f40) + # src='i440FX-pcihost' + # |-> dest='pci-bus-pc' type=0 (node=0x55914210ac70) + # src='x86_64/pc' + # |-> dest='i440FX-pcihost' type=0 (node=0x5591421117f0) + # src='' + # |-> dest='x86_64/pc' type=0 (node=0x559142111600) + # |-> dest='arm/raspi2' type=0 (node=0x559142110740) + ... + # } + # ALL QGRAPH NODES: { + # name='virtio-net-tests/announce-self' type=3 cmd_line='(null)' [available] + # name='arm/raspi2' type=0 cmd_line='-M raspi2 ' [UNAVAILABLE] + ... + # } + +The ``virtio-net-tests/announce-self`` test is listed as "available" in the +"ALL QGRAPH NODES" output. This means the test will execute. We can follow the +qgraph path in the "ALL QGRAPH EDGES" output as follows: '' -> 'x86_64/pc' -> +'i440FX-pcihost' -> 'pci-bus-pc' -> 'pci-bus' -> 'virtio-net-pci' -> +'virtio-net'. The root of the qgraph is '' and the depth first search begins +there. + +The ``arm/raspi`` machine node is listed as "UNAVAILABLE". Although it is +reachable from the root via '' -> 'arm/raspi2' the node is unavailable because +the QEMU binary did not list it when queried by the framework. This is expected +because we used the ``qemu-system-x86_64`` binary which does not support ARM +machine types. + +If a test is unexpectedly listed as "UNAVAILABLE", first check that the "ALL +QGRAPH EDGES" output reports edge connectivity from the root ('') to the test. +If there is no connectivity then the qgraph nodes were not set up correctly and +the driver or test code is incorrect. If there is connectivity, check the +availability of each node in the path in the "ALL QGRAPH NODES" output. The +first unavailable node in the path is the reason why the test is unavailable. +Typically this is because the QEMU binary lacks support for the necessary +machine type or device. + Creating a new driver and its interface """""""""""""""""""""""""""""""""""""""""