ci/virgl: Special-case llvmpipe parallelisation

When we're running VirGL/Venus, we sometimes want to invert our
parallelism. As some commands can serialise at the host level, we don't
always want to launch as many test clients as we have CPU cores.
Instead, we want to use our parallelism for llvmpipe's rendering, and
launch only a single test at a time.

Signed-off-by: Daniel Stone <daniels@collabora.com>
Part-of: <https://gitlab.freedesktop.org/mesa/mesa/-/merge_requests/31110>

.gitlab-ci/crosvm-runner.sh

@@ -2,6 +2,16 @@
 # shellcheck disable=SC2086 # we want word splitting
 set -e
 
+# Instead of starting one dEQP instance per available CPU core, pour our
+# concurrency at llvmpipe threads instead. This is mostly useful for VirGL and
+# Venus, which serialise quite a bit at the host level. So instead of smashing
+# it with a pile of concurrent jobs which don't actually parallelise very well,
+# we use that concurrency for llvmpipe/lavapipe's render pipeline.
+if [ -n "${PARALLELISE_VIA_LP_THREADS:-}" ]; then
+    export LP_NUM_THREADS="${FDO_CI_CONCURRENT:-4}"
+    export FDO_CI_CONCURRENT=1
+fi
+
 # If run outside of a deqp-runner invoction (e.g. piglit trace replay), then act
 # the same as the first thread in its threadpool.
 THREAD=${DEQP_RUNNER_THREAD:-0}

src/gallium/drivers/virgl/ci/gitlab-ci-inc.yml

@@ -71,7 +71,8 @@
   variables:
     HWCI_KERNEL_MODULES: vhost_vsock
     HWCI_KVM: "true"
-    HWCI_TEST_SCRIPT: "LP_NUM_THREADS=${FDO_CI_CONCURRENT} FDO_CI_CONCURRENT=1 /install/crosvm-runner.sh /install/piglit/piglit-traces.sh"
+    HWCI_TEST_SCRIPT: "/install/crosvm-runner.sh /install/piglit/piglit-traces.sh"
+    PARALLELISE_VIA_LP_THREADS: 1
     GPU_VERSION: virgl
     DRIVER_NAME: virgl
     GALLIUM_DRIVER: virgl