ci: enable BENCH_CMD

The patch enable environment variable `BENCH_CMD` introduced in
a previous commit. The `taskset` alone will pin all the process
threads into a single (random) isolated CPU, there's a ticket [1]
about this in the Linux kernel bugtracker. The workaround is using
realtime scheduler for the isolated task using `chrt` [2], e. g.:
`taskset 0xef chrt 50`.

1. https://bugzilla.kernel.org/show_bug.cgi?id=116701
2. https://www.man7.org/linux/man-pages/man1/chrt.1.html

NO_CHANGELOG=performance testing
NO_DOC=performance testing
NO_TEST=performance testing

.github/actions/install-deps-debian/action.yml

@@ -19,7 +19,8 @@ runs:
           libbenchmark-dev \
           autoconf \
           automake \
-          libtool
+          libtool \
+          util-linux
 
         luarocks install luacheck 0.26.1
         gem install coveralls-lcov

.github/workflows/perf_micro.yml

@@ -78,6 +78,16 @@ jobs:
         run: sh ./perf/tools/setup_env.sh
       - name: test
         run: make -f .test.mk test-perf
+        env:
+          # The taskset alone will pin all the process threads
+          # into a single (random) isolated CPU, see
+          # https://bugzilla.kernel.org/show_bug.cgi?id=116701.
+          # The workaround is using realtime scheduler for the
+          # isolated task using chrt, e. g.:
+          # sudo taskset 0xef chrt 50.
+          # But this makes the process use non-standard, real-time
+          # round-robin scheduling mechanism.
+          BENCH_CMD: "taskset 0xfe chrt 50"
       - name: Aggregate benchmark results
         run: make -f .test.mk test-perf-aggregate
       - name: Send statistics to InfluxDB

.test.mk

@@ -74,6 +74,7 @@ test-release: CMAKE_PARAMS = -DCMAKE_BUILD_TYPE=RelWithDebInfo \
 test-release: build run-luajit-test run-test
 
 .PHONY: test-perf
+test-perf: CMAKE_ENV = BENCH_CMD="${BENCH_CMD}"
 test-perf: CMAKE_PARAMS = -DCMAKE_BUILD_TYPE=RelWithDebInfo \
                           -DENABLE_WERROR=ON \
                           -DTEST_BUILD=ON